Effects of half ironman competition on the development of late potentials

Objectives: The primary purpose was to evaluate the prevalence of late pote ntials (LPs) in triathletes before and after a half ironman triathlon. The secondary purpose was to examine whether LPs are the electrocardiographic e xpression of a greater myocardial mass. Methods: Nine asymptomatic male tri athletes (mean age +/- SD, 32 +/- 5 yr) were examined using signal-averaged ECG (SAECG) 48-72 h before (PRE), immediately after (POST), and 24-48 h af ter the completion (RECOVERY) of a half ironman triathlon. Late potentials were considered to be present if two of the following SAECG anomalies were observed: 1) a prolonged filtered QRS (fQRS) complex (greater than or equal to 114 ms). 2) a lengthened low amplitude signal (LAS) duration (>38 ms), and/or 3) a low root mean square (RMS) voltage of the last 40 ms of the fQR S (<20 mu V). Left ventricular dimensions were determined at PRE using M-mo de echocardiography. Results: There were no significant differences between PRE, POST, and RECOVERY in the fQRS duration, the LAS duration, or the RMS voltage. Two athletes displayed a single SAECG abnormality during PRE and two SAECG anomalies (i.e., LPs) during POST. Late potentials remained in on e of the two athletes during RECOVERY. A moderate relationship existed betw een fQRS and left ventricular mass (r = 0.67, P < 0.05). Conclusions: Ultra -endurance training and/or events do not lead to LPs in the majority of tri athletes who do not possess ventricular arrhythmias. However, a small subse t of triathletes do display SAECG anomalies, which are augmented by an ultr a-endurance event and may persist even after recovery from the event. Left ventricular mass does not affect overall SAECG parameters.