INSIDE THIS ISSUE OF JACC
Inside This Issue of JACC
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Acute Coronary Syndromes
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Higher Clopidogrel Loading Doses Achieve Faster, Stronger Platelet Inhibition.
There is some discrepancy in the literature about the optimal loading dose of clopidogrel. Montalescot and colleagues randomized 100 patients with acute coronary syndromes to either 300, 600, or 900 mg of clopidogrel. Blood samples were then collected for the next 24 h to determine the optimal regimen for rapid and reliable inhibition of adenosine diphosphate-induced platelet aggregation. Both 600- and 900-mg doses resulted in platelet inhibition that was faster and more robust than 300-mg doses; there was a trend suggesting that 900 mg was more effective than 600 mg. No adverse events were apparent with the higher loading doses. Larger studies will be needed to know if this faster platelet inhibition leads to improved clinical outcomes, but this study suggests that 300 mg may not be enough to quickly inhibit platelet aggregation. See page 931. See figure.
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Coronary Artery Disease
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Physician Preference Leads to Superior Outcomes for CABG Versus PCI.
There is still no consensus on the best treatment for patients with stable multivessel coronary artery disease and preserved left ventricular function. The MASS II (Medicine, Angioplasty, or Surgery Study II) randomized patients deemed eligible for each to 1 of the 3 treatments strategies. Prior to randomization, 2 physicians were asked their personal recommendation for the subjects based on their clinical situation. For this current study, subjects were stratified according to whether or not they were randomized to the clinician-preferred strategy. Subjects for whom the clinician preference and the randomization were concordant were found to have superior outcomes to those where there was discordance. Further probing of the data revealed that the difference was mostly due to patients with complex anatomy being referred for percutaneous coronary intervention and then having to undergo subsequent revascularizations. This study suggests that clinical judgment is an important criterion when choosing between revascularization options. See page 948. See figure.
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Coronary Artery Disease
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Preoperative Stress Testing May Not be Necessary.
Current American College of Cardiology/American Heart Association guidelines recommend preoperative evaluations for ischemia in high- and intermediate-risk patients scheduled for moderate or high-risk surgeries, but the benefit of preoperative revascularization has been questioned. Delaying surgery until stress testing and/or revascularization can occur may put patients at unneeded risk from their underlying condition. The DECREASE-II study sought to evaluate the benefit of preoperative stress testing in patients assigned to a fairly aggressive regimen of beta blockade. There were 2 major findings in this study. First, there was no benefit in reduction of non-fatal myocardial infarctions at 30 days for preoperative stress testing and second, the risk of this end point directly correlated with the heart rate at the time of surgery. This study suggests that not all intermediate-risk patients referred for surgery benefit from preoperative stress testing and that perioperative beta blockade should be titrated to a target heart rate <65 beats/min. See page 964. See figure.
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Heart Rhythm Disorders
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No Benefit to Early Cardioversion for Atrial Fibrillation.
Atrial electrical remodeling is known to occur quickly with atrial fibrillation (AF) and has led to the belief that the longer a patient is in AF prior to cardioversion, the less likely they are to be successfully cardioverted. The VERDICT trial was designed to test the hypothesis that early cardioversion will reduce AF recurrences and be more successful for long-term maintenance of sinus rhythm. A second aim of the study was to test whether verapamil was superior to digoxin for preventing AF by reducing atrial calcium overload. Patients were randomized in a 2 x 2 factorial design to either acute cardioversion within 24 h for each episode of AF or regularly scheduled cardioversion, and then randomized to either verapamil or digoxin for rate control. Neither strategy was superior to the other, although digoxin without beta blockade appeared to be inferior to verapamil. This study challenges the notions that elective AF cardioversions should be scheduled as quickly as possible, and that calcium-channel blockers are the preferred agent for reducing the likelihood of AF reversion. See page 1001.
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Cardiac Imaging
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Strong Correlation Between Coronary Artery Calcification and Reduced Myocardial Perfusion.
Coronary artery calcification (CAC) detected by computed tomography has been correlated with perfusion defects and increased cardiovascular risk. Investigators from the MESA trial compared CAC with MRI-measured myocardial perfusion at baseline and during hyperemia. In this asymptomatic cohort, there was a strong and inverse association between CAC and myocardial perfusion, suggesting that CAC is not only a marker of a greater likelihood of hemodynamically significant stenoses, but may also correlate with endothelial dysfunction. This study provides evidence that CAC, thought to be an indicator of structural stenoses, is closely linked with and complementary to physiologic measures of myocardial perfusion. See page 1018. See figure.
Related Article
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A Randomized Comparison of High Clopidogrel Loading Doses in Patients With Non–ST-Segment Elevation Acute Coronary Syndromes: The ALBION (Assessment of the Best Loading Dose of Clopidogrel to Blunt Platelet Activation, Inflammation and Ongoing Necrosis) Trial
- Gilles Montalescot, Georges Sideris, Catherine Meuleman, Claire Bal-dit-Sollier, Nicolas Lellouche, Ph. Gabriel Steg, Michel Slama, Olivier Milleron, Jean-Philippe Collet, Patrick Henry, Farzin Beygui, Ludovic Drouet for the ALBION Trial Investigators
J. Am. Coll. Cardiol. 2006 48: 931-938.
[Abstract]
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Acute Coronary Syndromes
Coronary Artery Disease
