Concurrent Exercise-Associated Ventricular Complexes and a Prolonged QT Interval are Associated with Evidence of Myocarditis

Background: Precise myocardial tissue characterization in subjects with exercise-associated ventricular ectopy and prolonged QT interval but no obvious structural heart disease might facilitate further risk stratification. There is no data assessing QT intervals in patients with exercise-associated premature ventricular complexes (PVCs). Cardiovascular magnetic resonance (CMR) enables us to non-invasively assess myocardial scar and oedema. The purpose of our study was to assess the QT intervals in patients with exercise-associated premature ventricular complexes (PVCs). Methods: We analyzed the QT and QTc intervals of the 162 consecutive patients with documented exerciseassociated PVCs but no history or evidence of coronary heart disease or cardiomyopathy we previously examined. Findings were compared with those from 182 new controls without exercise-associated PVCs matched for gender and age. Continuous 12-holder ECG during upright bicycle exercise test and ECG-triggered, T2-weighted, fast spin echo triple inversion recovery sequences and late gadolinium enhancement were obtained, as were LV function and dimensions. Results: QT and QTc intervals were significantly prolonged in patients compared to controls (396.3 ± 33.5 ms vs. 385.9 ± 28.4 ms, p=0.002 and 431.7 ± 26.2 ms vs. 419.9 ± 26.6 ms, p=0.0001). Eighty five percent of patients with exercise-associated PVCs and prolonged QT intervals had structural abnormalities in the myocardium suggestive of acute or remote myocarditis or myopericarditis. Conclusion: Patients with exercise-associated PVCs showed prolonged QT intervals compared to controls. As a long QT interval is predictive of increased risk for arrhythmias or sudden cardiac death these findings may supply a potential mechanism for explaining the increased risk of some patients with exercise-associated PVCs.