(Circulation. 2000;101:616.)
© 2000 American Heart Association, Inc.
Clinical Investigation and Reports |
From the Departments of Medicine (A.J.M., W.Z.), Biostatistics (W.J.H.), and Community and Preventive Medicine (J.L.R., M.L.A.), University of Rochester School of Medicine and Dentistry, Rochester, NY; the Department of Medicine (R.S.C.), University of Virginia Health Sciences Center, Charlottesville, Va; the Department of Cardiology (P.J.S.), Policlinico San Matteo IRCCS and University of Pavia; Molecular Cardiology and Electrophysiology Laboratory (S.G.P., C.N.), Fondazione S. Maugeri IRCCS, Pavia, Italy; the Department of Medicine (G.M.V., L.Z., K.T.), University of Utah School of Medicine, Salt Lake City, Utah; the Heiden Department of Cardiology (J.B., A.M.), Bikur Cholim Hospital, Hebrew University, Jerusalem, Israel; the Department of Pediatric Cardiology (J.A.T.), Baylor College of Medicine, Houston, Tex; and the Section of Cardiology (E.H.L.), Department of Clinical and Experimental Medicine, Universita Degli Studi Di Perugia, Perugia, Italy.
Correspondence to Arthur J. Moss, MD, Heart Research Follow-up Program, Box 653, University of Rochester Medical Center, Rochester, NY 14642. E-mail heartajm{at}heart.rochester.edu
| Abstract |
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Methods and ResultsThe study population comprised 869 LQTS patients treated with ß-blockers. Effectiveness of ß-blockers was analyzed during matched periods before and after starting ß-blocker therapy, and by survivorship methods to determine factors associated with cardiac events while on prescribed ß-blockers. After initiation of ß-blockers, there was a significant (P<0.001) reduction in the rate of cardiac events in probands (0.97±1.42 to 0.31±0.86 events per year) and in affected family members (0.26±0.84 to 0.15±0.69 events per year) during 5-year matched periods. On-therapy survivorship analyses revealed that patients with cardiac symptoms before ß-blockers (n=598) had a hazard ratio of 5.8 (95% CI, 3.7 to 9.1) for recurrent cardiac events (syncope, aborted cardiac arrest, or death) during ß-blocker therapy compared with asymptomatic patients; 32% of these symptomatic patients will have another cardiac event within 5 years while on prescribed ß-blockers. Patients with a history of aborted cardiac arrest before starting ß-blockers (n=113) had a hazard ratio of 12.9 (95% CI, 4.7 to 35.5) for aborted cardiac arrest or death while on prescribed ß-blockers compared with asymptomatic patients; 14% of these patients will have another arrest (aborted or fatal) within 5 years on ß-blockers.
Conclusionsß-blockers are associated with a significant reduction in cardiac events in LQTS patients. However, syncope, aborted cardiac arrest, and LQTS-related death continue to occur while patients are on prescribed ß-blockers, particularly in those who were symptomatic before starting this therapy.
Key Words: arrhythmia syncope death, sudden heart arrest long-QT syndrome
| Introduction |
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There has never been a randomized, double-blind, placebo-controlled trial to evaluate the safety and efficacy of ß-blockers in LQTS. It would be difficult to carry out a randomized trial with ß-blockers in LQTS at this time because of the apparent clinical efficacy of ß-blockers in this disorder.4 This study was undertaken to investigate the clinical effectiveness of ß-blockers in LQTS patients enrolled in the International LQTS Registry and to evaluate risk factors for syncope, aborted cardiac arrest, and death during prescribed ß-blocker therapy.
| Methods |
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ß-Blocker Therapy
ß-blocker therapy was initiated at the discretion of each
patients attending physician. Various ß-blockers were prescribed in
LQTS patients enrolled from around the world. During the initial
patient contact, we determined, to the extent possible, if ß-blockers
had been started, the specific ß-blocker initiated, the date started,
the prescribed dose, and the patients weight. At subsequent yearly
contacts, we recorded whether the patient continued taking
ß-blockers, and if so, the daily dose; if patients discontinued
therapy we recorded the date stopped. Among patients who died, we
retrospectively determined if the patient had been on a prescribed
ß-blocker before death.
LQTS-Related Cardiac Events
LQTS-related cardiac events include unexplained syncope, aborted
cardiac arrest requiring cardiac resuscitation, unexpected sudden death
exclusive of a known cause before age 41 years, and sudden death during
LQTS-related surgery (n=1).
Data Management
Clinical data were recorded on prospectively designed forms
and included patient and family history and demographic,
electrocardiographic, therapeutic, and cardiac event information. The
reported analyses used LQTS analytic database version
9.0 (released October 22, 1997).
Statistical Analysis
To evaluate the effect of ß-blocker therapy, a matched-period
analysis was performed. For each patient, periods of equal
duration before and after starting ß-blocker were identified, with
patients serving as their own controls. The number of cardiac events,
event rates per patient, and event rates per year were determined for
the matched periods and aggregated or averaged over patients. The event
frequencies after initiation of ß-blockers were determined using both
an intention-to-treat-type approach (all patients started on
ß-blockers were included in the subsequent matched-period
analysis) and an on-treatment approach (patients were censored
during the time they were known to be off ß-blockers for >2 days).
Numbers of cardiac events >25 for a given patient before or after
starting ß-blockers were counted as 25 (n=18 patients), and rates of
cardiac events >5 per patient per year were treated as 5 (n=62
patients). When comparing the numbers of patients with any cardiac
event before and after starting ß-blockers, McNemars
2 test was used. When comparing counts of
cardiac events or rates of cardiac events, Wilcoxons signed
rank test was used. All P values are 2-sided.
To identify risk factors for cardiac events during prescribed ß-blocker therapy, we used the Cox proportional hazards method.9 The response studied was the duration of time until an end point occurred and up to 2 days after discontinuing therapy. The potential risk factors studied were demographic and clinical characteristics of patients before ß-blocker therapy was initiated. To estimate the cumulative probability of events over time, the cumulative hazard method was used with a log transformation for constructing confidence limits.
| Results |
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The dose and the dose per kilogram body weight of 4
different ß-blockers prescribed at initiation of therapy and
during follow-up (on average, 2.5 years later) are presented in
Table 2
. For the most part, there was an
increase in ß-blocker dosage during follow-up. The prescribed
ß-blocker doses were similar in probands and affected family members.
The percentage of patients remaining continuously on prescribed
ß-blockers 5 years after initiation of therapy was 82% (Figure 1
).
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Cardiac Events and Cardiac Event Rates During Matched Time
Periods
The average durations of risk exposure before and after starting
ß-blocker therapy were similar (
5 years) in the probands and the
affected family members (Table 3
).
ß-blockers were associated with a small but significant reduction in
QTc. The number of patients with cardiac events, the number of events
per patient, and the event rate per patient per year were each
significantly reduced (P<0.001) after starting ß-blocker
therapy in probands and in affected family members (Table 3
).
The reduction in the rate of cardiac events was most marked in patients
with the highest pre-ß-blocker event rates (Figure 2A
and 2B
). Ten probands and 10 family
members died after starting ß-blockers, with 3 probands and 2 family
members having discontinued ß-blockers before death.
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A limited number of patients had ECGs before and after ß-blockers
(Table 4
). ß-blockers were associated
with a significant decrease in the calculated QTc interval in those who
were asymptomatic after initiation of ß-blockers; there
was a similar but nonsignificant reduction in QTc in those who
subsequently experienced syncope and a slight increase in QTc in those
with subsequent aborted cardiac arrest/death (Table 4
).
|
The ß-blocker results in the subset of 139 genotyped patients
are presented in Table 5
.
ß-blocker therapy had minimal effects on QTc in all 3
genotypes but was associated with a significant reduction in
events and event rates in LQT1 and LQT2 patients.
There was no evident effect of ß-blockers on events in the small
number of patients with LQT3. Of the 5 deaths that occurred
in the genotyped patients after starting ß-blockers, only 1
patient (LQT3) had discontinued therapy before death.
|
The dose of ß-blockers (milligrams per kilogram body weight per day)
was divided at the median for each of 4 ß-blockers (atenolol,
metoprolol, nadolol, and propranolol), and the reductions
in cardiac event rates with ß-blocker doses below and above the
median aggregated doses were similar (Figure 3
, top). Event-rate analyses were
also performed for propranolol doses at
1.5, 1.6 to 2.5,
and >2.5 mg/kg body wt per day, with significant and similar
event-rate reductions at each of 3 dosage levels (Figure 3
, bottom).
|
Risk Factors for Cardiac Events While on Prescribed
ß-blockers
To evaluate factors influencing the occurrence of cardiac events
while patients were on prescribed ß-blockers, we used the entire pre-
and post-ß-blocker experience (not limited to the matched time
periods) and omitted any time periods during which each patient was
known to be off ß-blockers for >2 days. The risk factors for
experiencing any cardiac event or for aborted cardiac arrest or death
while on prescribed ß-blockers are presented in Table 6
. Risk was higher in those with
ß-blocker therapy initiated at a young age. For those who experienced
syncope only or aborted cardiac arrest before starting ß-blockers,
the hazard ratios for any cardiac event on ß-blockers were similar
(6.0 and 5.1, respectively, Table 6
). The dominant risk factor
for experiencing aborted cardiac arrest or death on ß-blockers was a
pre-ß-blocker history of aborted cardiac arrest, with a hazard ratio
12.9 compared with those who were asymptomatic before
ß-blockers (Table 6
). Prior syncope only was less of a risk
factor, with a hazard ratio 3.1.
|
Variables that did not make significant contributions to the
time-to-event risk models, including QTc, are listed in Table 6
.
Similar hazard ratios to those reported in Table 6
were found
for the symptom categories when children <1 year of age at the time
ß-blockers were initiated (n=81) were excluded. Also, we found
similar hazard ratios when comparing therapy by decades when
ß-blockers were started (19801989 versus 19901997).
Estimates of the cumulative probability of cardiac events and of
aborted cardiac arrest or death over time on prescribed ß-blockers
for patients
10 years of age, subdivided by symptom status before
ß-blockers, are presented in Figure 4A
and 4B
. Among patients who were
symptomatic before initiation of ß-blockers, 32% (95%
CI, 27 to 37) will have recurrent symptoms or death within 5 years
while on ß-blockers (Figure 4A
). Among patients who had an
aborted cardiac arrest before ß-blockers, 14% (95% CI, 7 to 21)
will have another arrest (aborted or fatal) within 5 years while on
ß-blockers, with almost half of the 5-years arrest events within the
first 6 months after starting ß-blocker therapy (Figure 4B
).
These percentages are increased for those <10 years old when
ß-blockers were initiated (Table 6
).
|
LQTS-Related Death After Starting ß-blockers
Among 33 LQTS patients who died after starting ß-blockers, 20
deaths occurred during matched post-ß-blocker periods and 13
afterward, with 4 patients <1 year of age dying (Table 7
). Two thirds of the deaths were
females. Mean baseline QTc value among fatal cases (0.53±0.06) was
slightly longer than in the overall study population.
ß-blockers were started mostly before adolescence (mean age 9±8
years), with death on average 5 years later (mean age 14±9). Among 33
patients who died, 79% had one or more cardiac events before starting
ß-blockers, including 30% with one or more aborted cardiac arrests.
Seventy-six percent (25 of 33) of patients had a known prescription for
ß-blockers at last contact before death, but their compliance in
taking the ß-blockers on the day of death is uncertain.
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| Discussion |
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We are unable to compare the experience of patients on ß-blockers to what it would have been if the patients were not treated. Reliable evaluations on this issue can come only from a randomized trial, or possibly from a retrospective matched case-control analysis. We could not perform a case-control analysis because of the limited number of high-risk patients in the Registry who were not treated with ß-blockers.
There are several limitations associated with this observational,
retrospective study of the LQTS Registry. ß-blocker treatment was not
allocated at random, thus unmeasured factors could have influenced the
effects of therapy. We tried to minimize bias by using matched-period
analyses before and after initiation of ß-blockers, with
patients serving as their own controls. This approach could introduce
chronological bias if the naturally occurring cardiac event rate
declines with increasing age. We found that the cardiac event rates
before ß-blockers were stable for patients in the 10 to 40 age range,
and event analyses in this age group (data not shown) were
similar to those presented in Table 6
. We do not know
how compliant the patients were in taking the prescribed ß-blocker
therapy. Some patients who died while on ß-blockers may have been
noncompliant in taking their prescribed medication in the 24 hours
before.
The appropriate or optimal dose of ß-blockers in the treatment of
LQTS is uncertain. The average dose of ß-blockers prescribed for LQTS
patients in the Registry was somewhat below the generally recommended
therapeutic dose for patients with heart disease. Although the number
of patients with available data on dose of ß-blockers per kilogram
body weight per day is somewhat limited (Table 2
), we did not
observe a reduction in event rates at higher ß-blocker doses (Figure 3
). This unexpected lack of a dose-response effect warrants
further study.
Patients with LQT1 and LQT2 genotypes may be more susceptible to the precipitation of ventricular tachy-arrhythmias by adrenergic trigger mechanisms than patients with the rarer LQT3 mutation. In the present study, ß-blockers had similar effects in reducing cardiac event rates in LQT1 and LQT2 patients but did not eliminate aborted cardiac arrest or LQTS-related sudden death. Although the number of patients with LQT3 is quite small and the event rates in this genotype are quite low, no beneficial ß-blocker effect was evident in LQT3.
The arrhythmogenic mechanisms associated with LQTS are complex,
and adrenergic phenomena are unlikely to be the sole cause of
life-threatening tachyarrhythmias. The findings in
Table 4
suggest that a relationship exists between ß-blocking
QTc shortening and reduction in cardiac events.
Our findings indicate that ß-blocker therapy is not entirely effective in preventing arrhythmic sudden death in LQTS patients, possibly because of inadequate dosage, noncompliance, and/or incomplete effectiveness of ß-blockers in preventing ventricular fibrillation in this disorder. ICD therapy in combination with ß-blockers can be a life-saving approach in selected high-risk LQTS patients.4 8 As shown in the present study, LQTS patients with aborted cardiac arrest before ß-blocker therapy have a high likelihood of experiencing recurrent aborted cardiac arrest or death despite ß-blocker therapy; we now recommend ICD therapy and ß-blockers in these very high-risk LQTS patients.
| Acknowledgments |
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| Footnotes |
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Received May 3, 1999; revision received August 30, 1999; accepted September 21, 1999.
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J. B. Hobbs, D. R. Peterson, A. J. Moss, S. McNitt, W. Zareba, I. Goldenberg, M. Qi, J. L. Robinson, A. J. Sauer, M. J. Ackerman, et al. Risk of aborted cardiac arrest or sudden cardiac death during adolescence in the long-QT syndrome. JAMA, September 13, 2006; 296(10): 1249 - 1254. [Abstract] [Full Text] [PDF] |
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E. T. Locati QT Interval Duration Remains a Major Risk Factor in Long QT Syndrome Patients J. Am. Coll. Cardiol., September 5, 2006; 48(5): 1053 - 1055. [Full Text] [PDF] |
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Developed in Collaboration With the European Heart, D. P. Zipes, A. J. Camm, M. Borggrefe, A. E. Buxton, B. Chaitman, M. Fromer, G. Gregoratos, G. Klein, A. J. Moss, et al. ACC/AHA/ESC 2006 Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death--Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death) J. Am. Coll. Cardiol., September 5, 2006; 48(5): 1064 - 1108. [Full Text] [PDF] |
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Developed in Collaboration With the European Heart, D. P. Zipes, A. J. Camm, M. Borggrefe, A. E. Buxton, B. Chaitman, M. Fromer, G. Gregoratos, G. Klein, A. J. Moss, et al. ACC/AHA/ESC 2006 Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death: A Report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death) J. Am. Coll. Cardiol., September 5, 2006; 48(5): e247 - e346. [Full Text] [PDF] |
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D. P. Zipes, D. P. Zipes, A. J. Camm, M. Borggrefe, A. E. Buxton, B. Chaitman, M. Fromer, G. Gregoratos, G. Klein, A. J. Moss, et al. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death--executive summary: A report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death) Developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Eur. Heart J., September 1, 2006; 27(17): 2099 - 2140. [Full Text] [PDF] |
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Writing Committee Members, D. P. Zipes, A. J. Camm, M. Borggrefe, A. E. Buxton, B. Chaitman, M. Fromer, G. Gregoratos, G. Klein, A. J. Moss, et al. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: A report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death) Developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society Europace, September 1, 2006; 8(9): 746 - 837. [Full Text] [PDF] |
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M. Viitasalo, L. Oikarinen, H. Swan, H. Vaananen, J. Jarvenpaa, H. Hietanen, J. Karjalainen, and L. Toivonen Effects of Beta-Blocker Therapy on Ventricular Repolarization Documented by 24-h Electrocardiography in Patients With Type 1 Long-QT Syndrome J. Am. Coll. Cardiol., August 15, 2006; 48(4): 747 - 753. [Abstract] [Full Text] [PDF] |
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S. Quaglini, C. Rognoni, C. Spazzolini, S. G. Priori, S. Mannarino, and P. J. Schwartz Cost-effectiveness of neonatal ECG screening for the long QT syndrome Eur. Heart J., August 1, 2006; 27(15): 1824 - 1832. [Abstract] [Full Text] [PDF] |
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J. M. Karp and A. J. Moss Dental treatment of patients with long QT syndrome J Am Dent Assoc, May 1, 2006; 137(5): 630 - 637. [Abstract] [Full Text] [PDF] |
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D. A. Cesario and G. W. Dec Implantable Cardioverter- Defibrillator Therapy in Clinical Practice J. Am. Coll. Cardiol., April 18, 2006; 47(8): 1507 - 1517. [Abstract] [Full Text] [PDF] |
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M C S Hall and D M Todd Modern management of arrhythmias Postgrad. Med. J., February 1, 2006; 82(964): 117 - 125. [Abstract] [Full Text] [PDF] |
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A V Postma, I Denjoy, J Kamblock, M Alders, J-M Lupoglazoff, G Vaksmann, L Dubosq-Bidot, P Sebillon, M M A M Mannens, P Guicheney, et al. Catecholaminergic polymorphic ventricular tachycardia: RYR2 mutations, bradycardia, and follow up of the patients J. Med. Genet., November 1, 2005; 42(11): 863 - 870. [Abstract] [Full Text] [PDF] |
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W. Shimizu The long QT syndrome: Therapeutic implications of a genetic diagnosis Cardiovasc Res, August 15, 2005; 67(3): 347 - 356. [Abstract] [Full Text] [PDF] |
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E. A. Whitsel, E. J. Boyko, P. M. Rautaharju, T. E. Raghunathan, D. Lin, R. M. Pearce, S. A. Weinmann, and D. S. Siscovick Electrocardiographic QT Interval Prolongation and Risk of Primary Cardiac Arrest in Diabetic Patients Diabetes Care, August 1, 2005; 28(8): 2045 - 2047. [Full Text] [PDF] |
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J R Skinner Is there a relation between SIDS and long QT syndrome? Arch. Dis. Child., May 1, 2005; 90(5): 445 - 449. [Full Text] [PDF] |
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A. J. Moss and P. J. Schwartz 25th Anniversary of the International Long-QT Syndrome Registry: An Ongoing Quest to Uncover the Secrets of Long-QT Syndrome Circulation, March 8, 2005; 111(9): 1199 - 1201. [Full Text] [PDF] |
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G. Seebohm Activators of Cation Channels: Potential in Treatment of Channelopathies Mol. Pharmacol., March 1, 2005; 67(3): 585 - 588. [Abstract] [Full Text] [PDF] |
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P. Milberg, N. Reinsch, K. Wasmer, G. Monnig, J. Stypmann, N. Osada, G. Breithardt, W. Haverkamp, and L. Eckardt Transmural dispersion of repolarization as a key factor of arrhythmogenicity in a novel intact heart model of LQT3 Cardiovasc Res, February 1, 2005; 65(2): 397 - 404. [Abstract] [Full Text] [PDF] |
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A. D.J. Ten Harkel, M. Witsenburg, P. L. de Jong, L. Jordaens, M. Wijman, and A. A.M. Wilde Efficacy of an implantable cardioverter-defibrillator in a neonate with LQT3 associated arrhythmias Europace, January 1, 2005; 7(1): 77 - 84. [Abstract] [Full Text] [PDF] |
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C. E. Clancy and R. S. Kass Inherited and Acquired Vulnerability to Ventricular Arrhythmias: Cardiac Na+ and K+ Channels Physiol Rev, January 1, 2005; 85(1): 33 - 47. [Abstract] [Full Text] [PDF] |
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S. G. Priori, C. Napolitano, P. J. Schwartz, M. Grillo, R. Bloise, E. Ronchetti, C. Moncalvo, C. Tulipani, A. Veia, G. Bottelli, et al. Association of Long QT Syndrome Loci and Cardiac Events Among Patients Treated With {beta}-Blockers JAMA, September 15, 2004; 292(11): 1341 - 1344. [Abstract] [Full Text] [PDF] |
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E. Villain, I. Denjoy, J.M. Lupoglazoff, P. Guicheney, B. Hainque, V. Lucet, and D. Bonnet Low incidence of cardiac events with {beta}-blocking therapy in children with long QT syndrome Eur. Heart J., August 2, 2004; 25(16): 1405 - 1411. [Abstract] [Full Text] [PDF] |
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D. G Katritsis and A.J. Camm Nonsustained ventricular tachycardia: where do we stand? Eur. Heart J., July 1, 2004; 25(13): 1093 - 1099. [Abstract] [Full Text] [PDF] |
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P. J. Schwartz Stillbirths, Sudden Infant Deaths, and Long-QT Syndrome: Puzzle or Mosaic, the Pieces of the Jigsaw Are Being Fitted Together Circulation, June 22, 2004; 109(24): 2930 - 2932. [Full Text] [PDF] |
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P. J. Schwartz, S. G. Priori, M. Cerrone, C. Spazzolini, A. Odero, C. Napolitano, R. Bloise, G. M. De Ferrari, C. Klersy, A. J. Moss, et al. Left Cardiac Sympathetic Denervation in the Management of High-Risk Patients Affected by the Long-QT Syndrome Circulation, April 20, 2004; 109(15): 1826 - 1833. [Abstract] [Full Text] [PDF] |
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L. C. Hool Differential regulation of the slow and rapid components of guinea-pig cardiac delayed rectifier K+ channels by hypoxia J. Physiol., February 1, 2004; 554(3): 743 - 754. [Abstract] [Full Text] [PDF] |
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S. P. Etheridge, S. J. Compton, M. Tristani-Firouzi, and J. W. Mason A new oral therapy for long QT syndrome: Long-term oral potassium improves repolarization in patients with HERG mutations J. Am. Coll. Cardiol., November 19, 2003; 42(10): 1777 - 1782. [Abstract] [Full Text] [PDF] |
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R. Balasubramaniam, A. A Grace, R. C Saumarez, J. I Vandenberg, and C. L-H Huang Electrogram prolongation and nifedipine-suppressible ventricular arrhythmias in mice following targeted disruption of KCNE1 J. Physiol., October 15, 2003; 552(2): 535 - 546. [Abstract] [Full Text] [PDF] |
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W. Zareba, A. J. Moss, E. H. Locati, M. H. Lehmann, D. R. Peterson, W. J. Hall, P. J. Schwartz, G. M. Vincent, S. G. Priori, J. Benhorin, et al. Modulating effects of age and gender on the clinical course of long QT syndrome by genotype J. Am. Coll. Cardiol., July 2, 2003; 42(1): 103 - 109. [Abstract] [Full Text] [PDF] |
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M. Tateyama, J. Kurokawa, C. Terrenoire, I. Rivolta, and R.S. Kass Stimulation of Protein Kinase C Inhibits Bursting in Disease-Linked Mutant Human Cardiac Sodium Channels Circulation, July 1, 2003; 107(25): 3216 - 3222. [Abstract] [Full Text] [PDF] |
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S. G. Priori, P. J. Schwartz, C. Napolitano, R. Bloise, E. Ronchetti, M. Grillo, A. Vicentini, C. Spazzolini, J. Nastoli, G. Bottelli, et al. Risk Stratification in the Long-QT Syndrome N. Engl. J. Med., May 8, 2003; 348(19): 1866 - 1874. [Abstract] [Full Text] [PDF] |
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S. Yong, X. Tian, and Q. Wang LQT4 Gene: The "Missing" Ankyrin Mol. Interv., May 1, 2003; 3(3): 131 - 136. [Abstract] [Full Text] [PDF] |
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A. J. Moss Long QT Syndrome JAMA, April 23, 2003; 289(16): 2041 - 2044. [Full Text] [PDF] |
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P. D. Booker, S. D. Whyte, and E. J. Ladusans Long QT syndrome and anaesthesia Br. J. Anaesth., March 1, 2003; 90(3): 349 - 366. [Abstract] [Full Text] [PDF] |
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W. Shimizu, T. Noda, H. Takaki, T. Kurita, N. Nagaya, K. Satomi, K. Suyama, N. Aihara, S. Kamakura, K. Sunagawa, et al. Epinephrine unmasks latent mutation carriers with LQT1 form of congenital long-QT syndrome J. Am. Coll. Cardiol., February 19, 2003; 41(4): 633 - 642. [Abstract] [Full Text] [PDF] |
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J. Kurokawa, L. Chen, and R. S. Kass Requirement of subunit expression for cAMP-mediated regulation of a heart potassium channel PNAS, February 18, 2003; 100(4): 2122 - 2127. [Abstract] [Full Text] [PDF] |
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I M Van Langen, E Birnie, M Alders, R J Jongbloed, H Le Marec, and A A M Wilde The use of genotype-phenotype correlations in mutation analysis for the long QT syndrome J. Med. Genet., February 1, 2003; 40(2): 141 - 145. [Full Text] [PDF] |
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J. Nemec, J. B. Hejlik, W.-K. Shen, and M. J. Ackerman Catecholamine-Induced T-Wave Lability in Congenital Long QT Syndrome: A Novel Phenomenon Associated With Syncope and Cardiac Arrest Mayo Clin. Proc., January 1, 2003; 78(1): 40 - 50. [Abstract] [PDF] |
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X. H.T. Wehrens, M. A. Vos, P. A. Doevendans, and H. J.J. Wellens Novel Insights in the Congenital Long QT Syndrome Ann Intern Med, December 17, 2002; 137(12): 981 - 992. [Abstract] [Full Text] [PDF] |
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I. Splawski, K. W. Timothy, M. Tateyama, C. E. Clancy, A. Malhotra, A. H. Beggs, F. P. Cappuccio, G. A. Sagnella, R. S. Kass, and M. T. Keating Variant of SCN5A Sodium Channel Implicated in Risk of Cardiac Arrhythmia Science, August 23, 2002; 297(5585): 1333 - 1336. [Abstract] [Full Text] [PDF] |
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M. Chinushi, H. Kasai, M. Tagawa, T. Washizuka, Y. Hosaka, Y. Chinushi, and Y. Aizawa Triggers of ventricular tachyarrhythmias and therapeutic effects of nicorandil in canine models of LQT2 and LQT3 syndromes J. Am. Coll. Cardiol., August 7, 2002; 40(3): 555 - 562. [Abstract] [Full Text] [PDF] |
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C. Antzelevitch Sympathetic modulation of the long QT syndrome Eur. Heart J., August 2, 2002; 23(16): 1246 - 1252. [PDF] |
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W. Shimizu, Y. Tanabe, T. Aiba, M. Inagaki, T. Kurita, K. Suyama, N. Nagaya, A. Taguchi, N. Aihara, K. Sunagawa, et al. Differential effects of beta-blockade on dispersion of repolarization in the absence and presence of sympathetic stimulation between the lqt1 and lqt2 forms of congenital long qt syndrome J. Am. Coll. Cardiol., June 19, 2002; 39(12): 1984 - 1991. [Abstract] [Full Text] [PDF] |
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T. Nagatomo, C. T. January, B. Ye, H. Abe, Y. Nakashima, and J. C. Makielski Rate-dependent QT shortening mechanism for the LQT3 {Delta}KPQ mutant Cardiovasc Res, June 1, 2002; 54(3): 624 - 629. [Abstract] [Full Text] [PDF] |
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M. J. Ackerman, A. Khositseth, D. J. Tester, J. B. Hejlik, W.-K. Shen, and C.-b. J. Porter Epinephrine-Induced QT Interval Prolongation: A Gene-Specific Paradoxical Response in Congenital Long QT Syndrome Mayo Clin. Proc., May 1, 2002; 77(5): 413 - 421. [Abstract] [PDF] |
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S. G. Priori, C. Napolitano, M. Gasparini, C. Pappone, P. D. Bella, U. Giordano, R. Bloise, C. Giustetto, R. De Nardis, M. Grillo, et al. Natural History of Brugada Syndrome: Insights for Risk Stratification and Management Circulation, March 19, 2002; 105(11): 1342 - 1347. [Abstract] [Full Text] [PDF] |
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R. Chatrath, C.-b. J. Porter, and M. J. Ackerman Role of Transvenous Implantable Cardioverter-Defibrillators in Preventing Sudden Cardiac Death in Children, Adolescents, and Young Adults Mayo Clin. Proc., March 1, 2002; 77(3): 226 - 231. [Abstract] [PDF] |
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S. G. Priori, E. Aliot, C. Blomstrom-Lundqvist, L. Bossaert, G. Breithardt, P. Brugada, J. A. Camm, R. Cappato, S. M. Cobbe, C. Di Mario, et al. TASK FORCE ON SUDDEN CARDIAC DEATH, EUROPEAN SOCIETY OF CARDIOLOGY: Summary of Recommendations Europace, January 1, 2002; 4(1): 3 - 18. [Abstract] [PDF] |
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M. J. Ackerman, B. L. Siu, W. Q. Sturner, D. J. Tester, C. R. Valdivia, J. C. Makielski, and J. A. Towbin Postmortem Molecular Analysis of SCN5A Defects in Sudden Infant Death Syndrome JAMA, November 14, 2001; 286(18): 2264 - 2269. [Abstract] [Full Text] [PDF] |
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B Campanelli and J-M Chaudron Long term follow up of long QT syndrome treated by overdrive pacing Heart, November 1, 2001; 86(5): e14 - 14. [Abstract] [Full Text] [PDF] |
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D. V. Exner, G. J. Klein, and E. N. Prystowsky Primary Prevention of Sudden Death With Implantable Defibrillator Therapy in Patients With Cardiac Disease: Can We Afford to Do It? (Can We Afford Not To?) Circulation, September 25, 2001; 104(13): 1564 - 1570. [Full Text] [PDF] |
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P. Coumel and A. A.M. Wilde Learning From Mistakes: The Case of Clinical Electrophysiology: A Perspective on Evidence-Based Rhythmology Circulation, August 14, 2001; 104(7): 845 - 847. [Full Text] [PDF] |
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S.G. Priori, E. Aliot, C. Blomstrom-Lundqvist, L. Bossaert, G. Breithardt, P. Brugada, A.J. Camm, R. Cappato, S.M. Cobbe, C. Di Mario, et al. Task Force on Sudden Cardiac Death of the European Society of Cardiology Eur. Heart J., August 2, 2001; 22(16): 1374 - 1450. [PDF] |
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J. Kimbrough, A. J. Moss, W. Zareba, J. L. Robinson, W. J. Hall, J. Benhorin, E. H. Locati, A. Medina, C. Napolitano, S. Priori, et al. Clinical Implications for Affected Parents and Siblings of Probands With Long-QT Syndrome Circulation, July 31, 2001; 104(5): 557 - 562. [Abstract] [Full Text] [PDF] |
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R.N.W. Hauer, E. Aliot, M. Block, A. Capucci, B. Luderitz, M. Santini, and P.E. Vardas Indications for implantable cardioverter defibrillator (ICD) therapy. Study Group on Guidelines on ICDs of the Working Group on Arrhythmias and the Working Group on Cardiac Pacing of the European Society of Cardiology Eur. Heart J., July 1, 2001; 22(13): 1074 - 1081. [PDF] |
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J. A. Towbin, Z. Wang, and H. Li Genotype and Severity of Long QT Syndrome Drug Metab. Dispos., April 1, 2001; 29(4): 574 - 579. [Abstract] [Full Text] |
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