Tuesday, January 29, 2008

Ventricular Arrhythmias During Clinical Treadmill Testing and Prognos

Ventricular Arrhythmias During Clinical Treadmill Testing and Prognosis

Frederick E. Dewey, BA; John R. Kapoor, MD, PhD; Ryan S. Williams, MD; Michael J. Lipinski, MD; Euan A. Ashley, MRCP, DPhil; David Hadley, PhD; Jonathan Myers, PhD; Victor F. Froelicher, MD

Arch Intern Med. 2008;168(2):225-234.

Background Although exercise-associated ventricular arrhythmias are frequently observed during exercise testing, their prognostic significance remains uncertain. Therefore, we aimed to evaluate the clinical correlates and prognostic significance of exercise-associated premature ventricular complexes (PVCs) during and after exercise testing.

Methods We studied 1847 heart failure–free patients who underwent clinical treadmill testing between March 13, 1997, and January 15, 2004, in the Veterans Affairs Palo Alto Health Care System. Logistic regression was used to evaluate the clinical and exercise test associations of exercise and recovery PVCs. Propensity score–adjusted Cox survival analyses were used to evaluate the prognostic significance of exercise-associated PVCs.

Results Of the 1847 subjects, 850 (46.0%) developed exercise PVCs (median rate, 0.43 per minute) and 620 (33.6%) had recovery PVCs (median rate, 0.60 per minute). Resting PVCs, age, and systolic blood pressure were key predictors of both exercise and recovery PVCs. Whereas exercise PVCs were related to the heart rate increase with exercise, recovery PVCs were related to coronary disease (previous myocardial infarction, coronary revascularization procedure, or pathological Q waves on resting electrocardiogram) and ST-segment depression. During a 5.4-year mean follow-up, 161 subjects (8.7%) died, and 53 of these deaths (32.9%) were due to cardiovascular causes. Recovery PVCs, but not exercise PVCs, were associated with 71% to 96% greater propensity-adjusted mortality rates (hazard ratio, 1.96 [95% confidence interval, 1.31-2.91] for infrequent PVCs; hazard ratio, 1.71 [95% confidence interval, 1.07-2.73] for frequent PVCs compared with subjects without PVCs), and occurrence of recovery PVCs reclassified 33.2% of subjects with intermediate-risk Duke Treadmill Scores into higher-risk subgroups.

Conclusion In our heart failure–free population, recovery PVCs were associated with increased mortality and augmented established risk markers.

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