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Exercise-Induced Premature Ventricular Contractions Are Associated With Myocardial Ischemia Among Asymptomatic Adult Male Firefighters: Implications for Enhanced Risk Stratification

Background: Exercise-induced premature ventricular contractions (EI-PVCs) are associated with an increased risk of cardiovascular disease among asymptomatic adult males, but the underlying mechanisms remain understudied. Myocardial ischemia due to cardiovascular disease reduces coronary blood flow, may impair exercise performance, and initiates EI-PVCs; thus, EI-PVCs may be an early indicator of cardiovascular disease. Objective: The objective of this study was to determine whether EI-PVCs are associated with myocardial ischemia and reduced exercise performance among asymptomatic adult firefighters. Methods: Asymptomatic adult firefighters free of known cardiovascular disease underwent exercise treadmill testing. A 12-lead electrocardiography was placed on participants for 24 hr afterward to measure EI-PVCs in recovery. Univariate and multivariate binary logistic regression models were used to assess the odds of myocardial ischemia. Sensitivity and specificity analyses were conducted. Statistical significance was set at p < .05. Results: Participants comprised 86 asymptomatic adult males. The prevalence of myocardial ischemia was 30.8%. A single EI-PVC was associated with myocardial ischemia (χ2 = 8.98; p = .003). EI-PVC remained a significant predictor despite adjustment for other cardiovascular risks (odds ratio = 4.281, p = .038). Although not statistically significant, the EI-PVC group achieved lower total exercise time (11.4 ± 2.9 vs. 12.4 ± 3.0 min, p = .13), lower metabolic equivalent of tasks (METs; 11.6 ± 2.6 vs. 12.8 ± 2.3 METs, p = .06), and a lower maximum exercise speed (4.4 ± 0.7 vs. 4.7 ± 0.8 miles/hr, p = .07). Discussion: EI-PVCs are associated with myocardial ischemia among asymptomatic male firefighters, providing additional evidence of the association between EI-PVCs and myocardial ischemia and suggesting EI-PVCs as an early indicator of cardiovascular disease.