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Abstract & Commentary
Synopsis: These data should force us to look at factors other than the traditional variables we have used to assess risks among patients with a history of ventricular arrhythmias.
Source: Lampert R, et.al. J Am Coll Cardiol. 2004;43:2293-2299.
Lampert and colleages report a single center study on the influence of gender on ventricular arrhythmia recurrence in patients with coronary disease and implantable cardioverter defibrillators (ICDs). Lampert et al reviewed data on 650 consecutive patients who received an ICD with the ability to store diagnostic electrograms for ventricular tachycardia (VT) or ventricular fibrillation (VF) events between June 1990 and June2000. Only patients who had both coronary artery disease and an ICD, which could store multiple (>10) episodes, were included in the study. As a result, 399 patients formed the final study cohort. A large number of clinical and electrocardiographic variables were analyzed as potential predictors of arrhythmia recurrence. The variables analyzed included electrocardiographic, clinical, angiographic, and electrophysiologic study data.
The final group consisted of 340 men and 59 women. Women tended to be older, had a higher prevalence of diabetes and hypertension, and had a slightly higher left ventricular ejection fraction. However, aneurysms were seen in 38% of women vs only 16% of men. Electrocardiographic and electrophysiologic parameters were similar between men and women.
During an average follow-up of 30 ± 22 months, sustained VT or VF, requiring ICD therapy, occurred in 52% of men and 34% of women. Men also experienced more total VT and VF events, and had more electrical storms (3 or more episodes within 24 hours, 31% vs 7%). In a multivariate analysis including a number of factors, men remained more than twice as likely as women to undergo any VT or VF event (odds ratio, 2.20, 95% confidence interval 1.02-4.90). Other factors independently associated with VT or VF events at presentation were sustained VT, VT induction at electrophysiologic study, and absence of immediate or remote revascularization. Lampert et al then go on to discuss potential mechanisms for these findings. They conclude that both genders benefit from ICD therapy, but that the risk of recurrence is higher in men.
Comment by John P. DiMarco, MD, PhD
Numerous studies have shown that age-adjusted sudden death rates are lower in women than they are in men, and that even after an initial episode of cardiac arrest or ventricular tachycardia, rates of recurrence are lower in women than in men. However, those prior observations do not usually control for patients with only coronary artery disease. This interesting paper by Lampert et al suggests that even among patients with coronary disease, a gender difference in arrhythmia recurrence can be demonstrated.
The reasons for this are uncertain. Lampert et al, in this paper, considered numerous clinical factors, and could not identify any important characteristics that would seem to favor women over men. Importantly, diabetes and hypertension were more common in women than in men, and men were more likely to have undergone revascularization. These factors would have been expected to lower the risk in men. Men were slightly more commonly treated with beta blockers than were women, but this also should have been a factor in their favor. One would think that all of these factors would have worked to lower frequency of events among men than women, but the opposite was seen here.
There are many social and economic factors that have been implicated in sudden death rates. Teasing out the role of these factors from clinical trial data is often very difficult. However, the data presented by Lampert et al are quite provocative. They should force us to look at factors, other than the traditional variables we have used, to assess risks among patients with a history of ventricular arrhythmias.
Dr. DiMarco, Professor of Medicine, Division of Cardiology, University of Virginia, Charlottesville, is on the Editorial Board for Clinical Cardiology Alert.