Circulation. 2007;116:1433
doi: 10.1161/CIRCULATIONAHA.107.185632
(Circulation. 2007;116:1433.)
© 2007 American Heart Association, Inc.
Issue Highlights
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ATRIUM-SELECTIVE SODIUM CHANNEL BLOCK AS A STRATEGY FOR SUPPRESSION OF ATRIAL FIBRILLATION: DIFFERENCES IN SODIUM CHANNEL INACTIVATION BETWEEN ATRIA AND VENTRICLES AND THE ROLE OF RANOLAZINE, by Burashnikov et al.
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Ventricular proarrhythmia is a major hurdle in drug development
for therapy for atrial fibrillation. The cardiac sodium current
that is a determinant of conduction and excitability in atrium
and ventricles is a target for many antiarrhythmic drugs. Sodium-current
blockers can suppress atrial fibrillation in some patients,
but an adverse impact on mortality rate was observed with some
agents administered after myocardial infarction. The recently
approved antianginal drug ranolazine is a sodium-channel blocker
without adverse mortality effects in human trials. Burashnikov
and coworkers compared the electrophysiological effects of ranolazine
in canine atrial and ventricular muscle. The drug’s interesting
sodium channel–blocking effects and prolongation of action
potential duration were greater in the atrium than in the ventricles.
Ranolazine had efficacy against atrial fibrillation in tissue
models. Selective blockade of atrial sodium channels appears
to be a feasible target that warrants further exploration for
treating atrial fibrillation without ventricular proarrhythmic
effects. See p
1449.
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EFFECT OF DISTAL EMBOLIZATION ON MYOCARDIAL PERFUSION RESERVE AFTER PERCUTANEOUS CORONARY INTERVENTION: A QUANTITATIVE MAGNETIC RESONANCE PERFUSION STUDY, by Selvanayagam et al.
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The high resolution of cardiac magnetic resonance imaging and
the use of the delayed enhancement technique have suggested
that after percutaneous coronary intervention (PCI), small new
areas of necrosis may be seen in the vascular bed distal to
the stented stenosis. In this issue of
Circulation, Selvanayagam
and colleagues assess changes in perfusion reserve after PCI
and the effect of new local myocardial injury on perfusion reserve.
They found that at 24 hours after the PCI procedure, perfusion
reserve improves in normal myocardium. In segments with new
distal injury, however, perfusion reserve is further impaired
after PCI, although it generally recovers at 6 months. The high
resolution of cardiac magnetic resonance allowed the authors
to demonstrate that the blunting of perfusion reserve was limited
to the local territory showing evidence of new injury, but that
was not observed within the same vascular territory upstream
to the injury, suggesting a local microvascular process. These
data extend the knowledge of post-PCI perfusion and vascular
changes, and illustrate how advanced imaging modalities enhance
the study of pathophysiology. See p
1458.
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CLINICAL CHARACTERISTICS OF DIALYSIS PATIENTS WITH ACUTE MYOCARDIAL INFARCTION IN THE UNITED STATES: A COLLABORATIVE PROJECT OF THE UNITED STATES RENAL DATA SYSTEM AND THE NATIONAL REGISTRY OF MYOCARDIAL INFARCTION, by Herzog et al.
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In a comparative analysis of 3049 patients with acute myocardial
infarction in the United States Renal Data System and 534 395
patients in the National Registry of Myocardial Infarction,
dialysis patients were shown to have less frequent chest pain
and ST elevation. Patients on dialysis were less frequently
eligible for reperfusion, but of these, only 47% received some
type of reperfusion compared with 75% of patients who were not
on dialysis. Non-acute percutaneous coronary intervention was
performed in 8.2% of patients versus 18.6%, and evidence-based
therapies including aspirin, ß-blockers, and angiotensin-converting
enzyme inhibitors were less frequently used. Renal dialysis
patient outcomes were worse than those in non-dialysis patients.
In a logistic regression model, the odds ratio for in hospital
mortality was 1.498 (95% confidence interval, 1.340–1.674)
as compared with 534 395 patients not on dialysis. These data
highlight the difficulties of making an initial diagnosis of
acute myocardial infarction in patients on dialysis and the
under-treatment of this high risk cohort. See p
1465.
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Images in Cardiovascular Medicine
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Angiography of an Aneurysmal Aorto–Left Ventricular Tunnel.
See p
e356.
Vegetation Stalagmite in Left Atrium. See p e356.
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Correspondence
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See p
e362.
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ATRIUM-SELECTIVE SODIUM CHANNEL...
EFFECT OF DISTAL EMBOLIZATION...