Circulation. 2007;115:2369
doi: 10.1161/CIRCULATIONAHA.107.183526
(Circulation. 2007;115:2369.)
© 2007 American Heart Association, Inc.
Issue Highlights
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INDUCTIONLESS OR LIMITED SHOCK TESTING IS POSSIBLE IN MOST PATIENTS WITH IMPLANTABLE CARDIOVERTER-DEFIBRILLATORS/CARDIAC RESYNCHRONIZATION THERAPY DEFIBRILLATORS: RESULTS OF THE MULTICENTER ASSURE STUDY (ARRHYTHMIA SINGLE SHOCK DEFIBRILLATION THRESHOLD TESTING VERSUS UPPER LIMIT OF VULNERABILITY: RISK REDUCTION EVALUATION WITH IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR IMPLANTATIONS), by Day et al.
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Ensuring that an implantable defibrillator is configured to
provide a shock of sufficient energy for a high probability
of defibrillation has traditionally required induction of ventricular
fibrillation, usually at the time of implantation. Although
the risks of this defibrillation testing are low, adverse hemodynamic
consequences occasionally occur. In a multicenter trial, Day
et al exploited the known relationship between the shock strength
required to induce ventricular fibrillation and the energy required
to defibrillate in their evaluation of a testing scheme that
seeks to establish that adequate defibrillation energy is programmed,
based on the effect of serial shocks during the T wave that
infrequently induced ventricular fibrillation. Although the
procedure still requires sufficient analgesia and sophisticated
methods for timing the test shocks and is not appropriate for
all patients, the results suggest that a substantial number
of patients receiving implantable cardioverter-defibrillators
could potentially be spared induction of ventricular fibrillation.
See p 2382 (editorial p
2370).
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EVIDENCE FOR MICROVASCULAR DYSFUNCTION IN HYPERTROPHIC CARDIOMYOPATHY: NEW INSIGHTS FROM MULTIPARAMETRIC MAGNETIC RESONANCE IMAGING, by Petersen et al.
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Seminal studies almost 30 years ago documented the presence
of inducible ischemia, often clinically silent, in patients
with hypertrophic cardiomyopathy (HCM). Ischemia may contribute
to many of the pathophysiological features of HCM, including
diastolic dysfunction, and potentially creates a milieu for
lethal arrhythmias. In this issue of
Circulation, Petersen and
colleagues report on a comprehensive analysis of HCM patients
using cardiovascular magnetic resonance imaging of rest and
hyperemic myocardial blood flow and fibrosis and their relation
to wall thickness. Hyperemic blood flow was blunted compared
to referent controls. The frequency of endocardial blood flow
falling below epicardial blood flow rose with increasing wall
thickness, as did the incidence of segmental fibrosis. These
interesting data advance our understanding of the relation of
hypertrophy to perfusion and fibrosis in HCM and should stimulate
more extensive investigation examining the implications of these
data for the occurrence of sudden death in HCM. See p
2418.
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INCOMPLETE STENT APPOSITION AND VERY LATE STENT THROMBOSIS AFTER DRUG-ELUTING STENT IMPLANTATION, by Cook et al.
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Stent thrombosis is an infrequent but serious complication of
coronary stent placement. Recent evidence suggests that in drug-eluting
stents, thrombosis can occur very late (more than 1 year) after
placement. One of the proposed mechanisms is incomplete stent
apposition due to either inadequate initial deployment or acquired
malapposition because of plaque or thrombus regression. In this
observational study by Cook et al, intravascular ultrasound
measurements were obtained in 13 patients who presented with
very late stent thrombosis an average of 630 days after drug-eluting
stent implantation. These patients were compared with 144 control
patients who had intravascular ultrasound at 9 months. Incomplete
stent apposition occurred in 77% of those with very late stent
thrombosis and in 12% of the control patients. This high prevalence
suggests that incomplete stent apposition may play a role in
the pathophysiology of very late stent thrombosis. See p 2426
(editorial p
2379).
Visit http://circ.ahajournals.org:
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Clinician Update
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Implications and Treatment of Acute Hyperglycemia in the Setting
of Acute Myocardial Infarction. See p
e436.
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Images in Cardiovascular Medicine
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Cardiac Magnetic Resonance Imaging and Multidetector Computed
Tomography Scan Illustrating Damus–Kaye–Stansel
Operation. See p
e440.
Iatrogenic Aortic Valve Hematoma: A Life-Threatening Complication of Coronary Angiography. See p e443.
Intramural Atrial Hematoma After Catheter Ablation for Atrial Tachyarrhythmias. See p e446.
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Correspondence
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See p
e448.
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Letter by Hamon et al Regarding Article, "Coronary Multidetector Computed Tomography in the Assessment of Patients With Acute Chest Pain"
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INDUCTIONLESS OR LIMITED SHOCK...
EVIDENCE FOR MICROVASCULAR...