Circulation. 2008;118:1519-1520
doi: 10.1161/CIRCULATIONAHA.108.191021
(Circulation. 2008;118:1519-1520.)
© 2008 American Heart Association, Inc.
Clinical Summaries
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Clinical Outcome After Surgical Correction of Mitral Regurgitation Due to Papillary Muscle Rupture
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Papillary muscle rupture (PMR) after myocardial infarction (MI)
is rare but deadly. Radical treatment for PMR is mitral valve
surgery, which is associated with high operative mortality.
PMR presentation is usually catastrophic, and diagnosis often
is difficult because the murmur is heard inconsistently. Long-term
outcome of surgery is uncertain because of the small sizes of
the published series. Thus, clinical management is difficult,
and surgical decisions may be tentative. To address these issues,
we examined the outcome of 54 patients who underwent post-MI
PMR surgery between 1980 and 2000 at our institution. We confirmed
the seriousness of PMR presentation with shock, pulmonary edema,
or cardiac arrest in 91%. Operative mortality was high but was
lower with coronary artery bypass graft and tended to decrease
in recent years, declining from 67% (before 1990 without coronary
artery bypass graft) to 8.7% (after 1990 with coronary artery
bypass graft). Another development was valve repair, feasible
in 41% after 1990, but its impact on outcome cannot be determined
because of the small sample. We compared the long-term outcome
of operative survivors with that of patients with similar MI
but without PMR who had survived the first 30 days after MI.
This comparison showed identical 5-year survival and similar
heart failure rates. Thus, our study, while emphasizing the
seriousness of PMR, is encouraging: Recent surgery is more often
reparative, has markedly improved operative risk with coronary
artery bypass graft, and results in restoration of long-term
life expectancy and morbidity to that of a similar but uncomplicated
MI. These most recent encouraging developments emphasize the
importance of prompt diagnosis and aggressive therapeutic approach
for patients incurring PMR after MI. See p
1528.
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Passive Smoking and Risk of Peripheral Arterial Disease and Ischemic Stroke in Chinese Women Who Never Smoked
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We conducted a population-based cross-sectional study in an
urban Beijing sample of women who had never smoked to assess
the association between secondhand smoke (SHS) and risk of peripheral
arterial disease (PAD), stroke, and coronary heart disease in
China. SHS exposure was defined as exposure to another person’s
tobacco smoke at home or at work. PAD was defined by symptoms
of intermittent claudication and an ankle-brachial index of
<0.90. Among 1209 Chinese women who never smoked, 39.5% were
exposed to SHS. We found that compared with women who were not
exposed to SHS, among women who were exposed to SHS, risk of
intermittent claudication was increased by 87% and risk of PAD
assessed by ankle-brachial index <0.90 was increased by 47%,
with significant dose-response relationships for both number
of cigarettes exposed to and duration of exposure after adjustment
for established cardiovascular risk factors. PAD is an underdiagnosed
and undertreated condition in China;
43% of PAD patients were
asymptomatic, and most of them were unaware of their condition
and did not know the risk factors for PAD. Our results add to
the evidence that SHS exposure is associated with increased
risk of coronary heart disease by 69% and ischemic stroke by
56% in Chinese nonsmoking women. In China,
4% women are current
smokers, but >50% of women are exposed to SHS, and most people
are unaware of the serious health hazards of SHS. Thus, urgent
public health measures are warranted to protect individuals
from exposure to SHS. See p
1535.
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Prevalence, Clinical Significance, and Natural History of Left Ventricular Apical Aneurysms in Hypertrophic Cardiomyopathy
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The present study reports the prevalence, morphology, clinical
course, and management of an underrecognized subgroup of hypertrophic
cardiomyopathy (HCM) patients with left ventricular apical aneurysm.
Among a large cohort of HCM patients, 2% were identified with
a thin-rim apical aneurysms, which varied considerably in size
(transverse dimension, 10 to 66 mm), were dyskinetic/akinetic,
and were associated with transmural (and often more extensive)
myocardial scarring identified by late gadolinium enhancement
cardiovascular magnetic resonance. Sarcomere protein mutations
known to cause phenotypic expression of HCM were identified
in 3 of 9 genotyped patients, suggesting that these patients
are part of the broad HCM disease spectrum. In most patients,
the left ventricular chamber had an "hourglass" contour, with
midventricular hypertrophy producing muscular narrowing and
intracavitary gradients in some patients. Left ventricular apical
aneurysms were identified by 2-dimensional echocardiography
in only one half of the patients but were detected in all those
patients imaged by cardiovascular magnetic resonance. Over a
mean follow-up of 4 years, HCM patients with left ventricular
apical aneurysms experienced a substantial adverse event rate
(10.5%/y), including sudden death, appropriate ICD discharges,
nonfatal thromboembolic stroke, and progressive heart failure
and death. Therefore, identification of HCM patients with left
ventricular apical aneurysm requires a high index of suspicion,
often relying on cardiovascular magnetic resonance for both
diagnosis and detection of myocardial scarring. These data also
raise important management considerations in this subset of
HCM patients, including consideration for prophylactic implantable
cardioverter-defibrillator therapy and anticoagulation. See
p
1541.
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Functional Impairment of Von Willebrand Factor in Hypertrophic Cardiomyopathy: Relation to Rest and Exercise Obstruction
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Left ventricular outflow tract obstruction plays an important
role in the pathophysiology of hypertrophic cardiomyopathy (HCM).
Obstruction is present in
25% of patients at rest but in up
to 70% of patients during exercise. The long-term consequences
of obstruction (heart failure and cardiovascular death) are
thought to be related to wall-stress increase and myocardial
ischemia. Beyond the effect on myocardium, outflow gradient
could be involved in other pathophysiological alterations through
an increase in the shear stress level. High shear forces have
been shown to enhance proteolysis of the largest von Willebrand
factor (VWF) multimers. We previously demonstrated that VWF
impairment, defined as an acquired von Willebrand syndrome,
is common in aortic stenosis and is directly related to the
magnitude of obstruction. Moreover, VWF impairment favors abnormal
bleeding in aortic stenosis. Accordingly, we hypothesized that
outflow gradient could impair VWF in the obstructive form of
HCM. Outflow gradient was evaluated by rest and exercise echocardiography
in 62 patients. VWF impairment was frequent and was closely
and independently associated with the magnitude of obstruction.
A resting peak gradient of 15 mm Hg was sufficient to impair
VWF. Patients with exercise-induced obstruction exhibited an
intermediate pattern of VWF impairment compared with patients
with nonobstructive HCM and baseline obstructive HCM. Outflow
obstruction reduction was associated with an improvement in
VWF function. In addition, patients with obstructive HCM had
a trend toward abnormal spontaneous bleeding. Finally, these
data support the concept that acquired von Willebrand syndrome,
which is a recognized risk factor for bleeding, is common in
the obstructive form of HCM. See p
1550.
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Hypertension Subtype and Risk of Cardiovascular Disease in Chinese Adults
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We examined the relationship between hypertension subtype and
cardiovascular disease (CVD) incidence and mortality in a prospective
cohort study of 169 871 Chinese men and women aged
40 years.
Hypertension subtypes were defined as combined systolic and
diastolic hypertension (systolic blood pressure [SBP]
140 and
diastolic BP [DBP]
90 mm Hg), isolated systolic hypertension
(SBP
140 and DBP <90 mm Hg), isolated diastolic hypertension
(SBP <140 and DBP
90 mm Hg), and 2 categories of treated
hypertension (SBP <140 and DBP <90 mm Hg or SBP
140 and/or
DBP
90 mm Hg). All hypertension subtypes were associated with
an increased risk of CVD compared with participants with normal
BP. Compared with normotensives, combined systolic and diastolic
hypertension was associated with 2.73- and 2.53-fold increased
risk of CVD incidence and mortality; isolated systolic hypertension
was associated with 1.78- and 1.68-fold increased risk of CVD
incidence and mortality; isolated diastolic hypertension was
associated with 1.59- and 1.45-fold increased risk of CVD incidence
and mortality; treated hypertension with SBP <140 and DBP
<90 mm Hg was associated with 2.01- and 1.61-fold increased
risk of CVD incidence and mortality; and treated hypertension
with SBP
140 and/or DBP
90 mm Hg was associated with 3.37- and
2.88-fold increased risk of CVD incidence and mortality, respectively,
after adjustment for important covariables. These findings suggest
that more aggressive antihypertensive treatment efforts may
help to decrease CVD risk among those already affected with
inadequately treated or untreated hypertension, whereas the
primary prevention of hypertension may be most effective and
should be considered the first choice for curbing the rising
CVD epidemic in the Chinese population. See p
1558.
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Conditional Dicer Gene Deletion in the Postnatal Myocardium Provokes Spontaneous Cardiac Remodeling
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The adult heart is exquisitely sensitive to slight alterations
in gene expression to maintain normal morphological and hemodynamic
homeostasis. A newly discovered class of small ribonucleotide-based
regulators of gene expression, microRNAs, is being progressively
implicated in an increasing number of biological processes,
and the role of microRNAs in cardiovascular homeostasis and
disease is only recently being uncovered. MicroRNAs are small
RNAs that do not encode proteins but rather pair with their
target mRNAs to negatively regulate protein expression. In this
study, the global involvement of microRNAs in heart development
and function was assessed by deleting
Dicer, an endonuclease
required for the proper biogenesis of all microRNA species,
specifically in the postnatal myocardium. Targeted deletion
of
Dicer in the mouse heart and concomitant repression of proper
microRNA processing and target protein expression resulted in
spontaneous adverse ventricular remodeling, severe histopathology
in juvenile and adult myocardium, and premature death of juvenile
animals. Signs of heart failure including hemodynamic defects
and acute upregulation of "fetal" cardiac genes accompanied
the remarkably fast myocardial remodeling process of the
Dicer-depleted
adult myocardium. Altogether, these data provide clear evidence
for a crucial role for microRNAs in controlling postnatal myocardial
integrity and suggest a therapeutic potential of subsets of
microRNAs in the treatment of cardiac disorders such as chronic
heart failure. See p
1567.
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Incidence and Risk Factors for Stroke in American Indians: The Strong Heart Study
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The incidence of stroke and its determinants have not been examined
in a prospective and systematic fashion in the American Indian
population. In this population-based study of American Indians
who underwent standardized clinical and laboratory evaluation
during the period 1989 to 1992 and regular follow-up through
2004, the rate of first stroke was unusually high. After we
accounted for differences in age and sex, stroke incidence exceeded
that recorded in community-based studies of white and, notably,
black US populations, who have an especially high stroke rate.
Moreover, the 1-year case-fatality rate after stroke in American
Indians surpassed those of other populations. As in previous
epidemiological studies, age, hypertension, diabetes mellitus,
and smoking were independent predictors of stroke, as were microalbuminuria,
macroalbuminuria, and hyperglycemia. Diastolic but not systolic
blood pressure independently predicted stroke, which likely
reflects a preponderance of participants <65 years of age.
The independent relations of hypertension, diabetes, smoking,
and albuminuria (a marker of vascular damage and inflammation)
with stroke indicate that these factors heighten cerebrovascular
risk in populations where they are prevalent. Clinicians may
use this information to advise patients how to reduce the risk
of stroke by modifying their health behaviors or lifestyles
and consequently improve their risk factors. Amid the current
worldwide epidemics of obesity and diabetes, the findings may
also aid clinicians in determining prevention strategies that
target such risk factors. See p
1577.
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