Setting: Thirty-three medical centers in the Netherlands.
Synopsis: The study looked at 614 patients with permanent atrial fibrillation; 311 patients were randomized to lenient control and 303 to strict control. Calcium channel blockers, beta-blockers, or digoxin were dose-adjusted to control heart rate below 110 beats per minute (bpm) in the lenient control group versus 80 bpm in the strict control group.
Thirty-eight patients (12.9%) in the lenient control group and 43 (14.9%) in the strict control group reached the primary composite outcome of significant cardiovascular events (death, heart failure, stroke, embolism, major bleeding, major arrhythmia, need for pacemaker, or severe drug adverse event). Although no statistical difference in the frequency of these events between groups was detected, the study was dramatically underpowered due to unanticipated low event rates.
Bottom line: Although the lenient control group had far fewer outpatient visits and a trend toward improved outcomes, no definite conclusion regarding the management of permanent atrial fibrillation can be drawn from this underpowered noninferiority trial.
Citation: Van Gelder IC, Groenveld HF, Crijns HJ, et al. Lenient versus strict rate control in patients with atrial fibrillation. N Engl J Med. 2010;362(15):1363-1373.
Pneumococcal Vaccine Does Not Reduce the Risk of Stroke or Myocardial Infarction
Clinical question: Does pneumococcal vaccination reduce the risk of acute myocardial infarction (MI) and stroke?
Background: Studies have demonstrated that influenza vaccination reduces the risk of cardiac and cerebrovascular events. A single study has shown similar outcomes for the pneumococcal vaccination, although the study was limited by confounders and selection bias.
Study design: Retrospective cohort.
Setting: Large HMO in California.
Synopsis: More than 84,000 men participating in the California Men’s Health Study (CMHS) and enrolled in the Kaiser Permanente health plan were categorized as unvaccinated or vaccinated with the pneumococcal vaccine. Vaccinated patients had 10.73 first MIs and 5.30 strokes per 1,000 person-years, compared with unvaccinated patients who incurred 6.07 MIs and 1.90 strokes per 1,000 unvaccinated person-years based on ICD-9 codes.
Even with propensity scoring to minimize selection bias, no clear evidence of benefit was observed. One significant limitation is that 80% of the unvaccinated patients were younger than 60 years old, whereas 74% of the vaccinated patients were 60 or older; this might represent selection bias that cannot be overcome with propensity scoring.
Bottom line: In a population of men older than age 45, pneumococcal vaccination does not appear to reduce the risk of acute MI or stroke.
Citation: Tseng HF, Slezak JM, Quinn VP, et al. Pneumococcal vaccination and risk of acute myocardial infarction and stroke in men. JAMA. 2010;303(17):1699-1706.
No Durable Mortality Benefit from Endovascular Repair of Enlarged Abdominal Aortic Aneurysm
Clinical question: What is the cost and mortality benefit of endovascular versus open repair of abdominal aneurysms?