Aerobic Fitness and Risk of Ventricular Arrhythmia Following Physical Exertion

Abstract Background Brief episodes of physical exertion are associated with an immediately higher risk of cardiovascular events. Prior studies on the risk of ventricular arrhythmia (VA) shortly after exertion have not assessed if this risk differs by level of aerobic fitness or sedentary behaviour....

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Published in:Canadian journal of cardiology 2016-04, Vol.32 (4), p.533-538
Main Authors: Chahal, Harpreet S., BMSc, Mostofsky, Elizabeth, ScD, Mittleman, Murray A., MD DrPH, Suskin, Neville, MD MSc, Speechley, Mark, PhD, Skanes, Allan C., MD, Leong-Sit, Peter, MD MSc, Manlucu, Jaimie, MD, Yee, Raymond, MD, Klein, George J., MD, Gula, Lorne J., MD MSc
Format: Article
Language:English
Subjects:
Cardiovascular
Cross-Over Studies
Defibrillators, Implantable
Female
Humans
Incidence
Male
Middle Aged
Ontario - epidemiology
Physical Exertion - physiology
Physical Fitness
Prospective Studies
Risk Assessment
Risk Factors
Tachycardia, Ventricular - epidemiology
Tachycardia, Ventricular - etiology
Tachycardia, Ventricular - therapy
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Summary:Abstract Background Brief episodes of physical exertion are associated with an immediately higher risk of cardiovascular events. Prior studies on the risk of ventricular arrhythmia (VA) shortly after exertion have not assessed if this risk differs by level of aerobic fitness or sedentary behaviour. Therefore, we conducted a prospective cohort study of patients with implantable cardioverter-defibrillators (ICD) with a nested case-crossover analysis to examine the risk of VA shortly after exertion and whether this risk is modified by aerobic fitness and sedentary behaviour. Methods 97 consecutive patients were recruited at the time of ICD implant and 30 confirmed events occurred among patients who completed interviews about physical exertion preceding ICD therapy. We compared the frequency of exertion within an hour of ICD discharge to each patient's usual frequency of exertion reported at the time of ICD implant. Results Within an hour of episodes of exertion, the risk of VA was 5.3 (95% CI 2.7 – 10.6) times greater compared to periods of rest. The association was higher among patients with aerobic fitness below the median (RR[relative risk]=17.5, 95% 5.2 – 58.5) than for patients with aerobic fitness above the median (RR=1.2, 95% CI 0.4 – 4.2, p-homogeneity = 0.002) and higher among patients who were sedentary (RR=52.8, 95% 10.1 – 277) compared to individuals who were not sedentary (RR=3.2, 95% 1.3 – 7.6, p-homogeneity=0.0002). Conclusions Within one hour of episodes of exertion, there is an elevated risk of VA, especially among individuals with lower levels of aerobic fitness and with sedentary behaviour.
ISSN:0828-282X
1916-7075
DOI:10.1016/j.cjca.2015.12.026