T-Wave Alternans in Risk Stratification of Athletes with Ventricular Arrhythmias: Correlation with Electrophysiological Testing Results

Abstract

Introduction T-wave alternance (TWA) is a beat-to-beat variation in vector and amplitude of T wave, due to localized alternation in action potential duration. The use of advanced signal processing techniques and high-resolution electrodes allowed to detect the fluctuations in the T wave at the microvolt scale and to reduce ambient noise. The usefulness of TWA in predicting the risk of ventricular tachyarrhythmias has been widely demonstrated in several clinical conditions. Aim of our study was to evaluate the role of TWA to stratify the risk of sudden cardiac death in athletes with complex ventricular tachyarrhythmias (VT), and to document a possible correlation between TWA and electrophysiological testing (EPT) results. Methods We studied 20 patients (12 M, mean age 29 years, range 13-45). All subjects were athletes (4 of them classified as “elite athletes”) engaged in 5 different sports, affected by VT (> 50 premature ventricular complexes/hour or non-sustained VT). 16 patients (80%) were symptomatic for palpitation, syncope or pre-syncope. In all cases a basic cardiological evaluation was performed, including ECG, 24-hour ambulatory ECG, echocardiogram, exercise test, TWA and EPT. Coronary angiography was performed in 6 cases and cardiac magnetic resonance in 10. Any therapeutic decision was taken by combining information about clinical presentation of each patient with their own instrumental findings. Results TWA was negative in 15 patients (75%), positive in 2 (10%) and undetermined in 3 (15%). All subjects with negative TWA did not show induction of malignant VTs (ventricular tachycardia or ventricular fibrillation) at EPT. The 2 patients with positive TWA also had malignant VT induced by an EPT and received an implantable cardioverters defibrillator (ICD). In 2 of the 3 patients with undetermined TWA, who had a history of non-sustained VT, malignant VT were induced at EPT, but their clinical setting excluded the use of an ICD. During follow-up, the patients treated with ICD showed appropriate device interventions to terminate spontaneous VT. In all other subjects we observed no episodes of malignant VT. Conclusion TWA confirm its role as a simple and non-invasive test, and it seems useful for prognostic stratification of athletes with VT. Similarly to the literature, TWA predictivity values are promising also in such a specific population, even if larger cohorts are required to refine such calculations. If confirmed in larger trials, combining TWA and EPT may be a useful approach to improve risk stratification of sudden cardiac death in athletes with positive TWA.