Objective The clinical significance of ECG abnormalities during atrial fibrillation (AF) rhythm is poorly understood. The aim of the current study was to explore the impact of inverted T wave on cardiac prognosis in patients with AF.

Methods The current study enrolled 2709 patients with AF whose baseline ECG was available from a Japanese community-based prospective survey, the Fushimi AF Registry, and the impact of inverted T wave in baseline ECG at AF rhythm on the composite of cardiac death, myocardial infarction and hospitalisation due to heart failure was examined.

Results Intraventricular conduction delay, ST segment depression and inverted T wave were observed in 15.8%, 24.7% and 41.4% of baseline ECG with a mean heart rate of 94.7 beats per minute. The median follow-up duration was 5.0 years. The incidence rate of the composite cardiac endpoint was significantly higher in patients with inverted T wave than those without (5.8% vs 3.3% per patient-year, log-rank p<0.01). The higher risk associated with inverted T wave was consistent even for individual components of the composite cardiac endpoint. By multivariable analysis, inverted T wave was an independent predictor of the composite cardiac endpoint (HR 1.53, 95% CI 1.26 to 1.85, p<0.01). Inverted T wave was detected in 15.7% at anterior leads, 19.8% at inferior leads and 26.6% at lateral leads. The location of inverted T wave was not associated with risk of composite cardiac endpoint.

Conclusions Inverted T wave was commonly observed in patients with AF and its presence during AF rhythm was associated with subsequent cardiac events.