Microvolt T-Wave alternans as predictors of malignant tachyarrhythmias in athletes

Giorgio Galanti, Francesco Furlanello (), Paolo Manetti, Andrea Capalbo, Nicola Pucci, Antonio Michelucci, Francesco Terrasi (), Daniele Marangoni (),G. Pettinati (****), Riccardo Cappato (*)

Sport Medicine Centre, University of Florence; Department of Clinical Arrhythmia and Electrophysiology, San Donato Milanese Hospital, Milano(); Villa Bianca Hospital, Trento (); University of Verona (); Cardiology Dep, Ferrari Hospital, Casarano, Lecce(****).

Short title: T-wave alternans and arrhythmias in athletes

For corrispondence: Giorgio Galanti, Centro di Riferimento Regionale di Medicina dello Sport, Clinica Medica Generale e Cardiologia, Dipartimento dell’Area Critica Medico-Chirurgica, Università degli Studi, Ospedale Careggi.

Viale Morgagni n. 85, 50134 Firenze

e-mail address: g.galanti@dac.unifi.it

Abstract

Exercise-induced heart rate increase can stimulate malignant arrhythmic events in a pathological cardiac subjet, even in absence of early symptoms. T-Wave alternans (TWA) has been associated with malignant ventricular arrhythmias. Recently sophisticated signal-processing techniques were able to measure TWA down to one-millionth per volt (microvolt-TWA). Several studies confirmed the equivalence of microvolt-TWA and electrophysiology test (EPS) in cardiopathic patients, but no data are available in population of competitive athletes with severe ventricular arrhythmias, where it is important to separate a “paraphysiologic” arrhythmic training-induced subject from a pathological one.

We selected 81 competitive athletes, aged between 12 to 46 years old, (mean age: 24.3±4.5 yrs), 48 of them totally normal including elite type (group A, mean age: 24.5±4.1) and 33 of them (group B, mean age: 23.9±1.5) with important arrhythmias (ventricular ectopic beats>10/hour also complex or non sustained and sustained ventricular tachycardia).

All athletes were evaluated by exercise-stress test (bicycle in 48 cases or treadmill), increasing the heart rate up to 110 beats/min in about 15 minutes. Microvolt TWA have been performed using the Heart Wave System with Micro-V Sensors (Cambridge Heart Inc., Boston). Analysis of the results have been performed automatically by the Cambridge Heart system interpretation software with confirmation by an expert (100% agreement). Group B underwent EPS in order to evaluate the inducibility to sustained ventricular tachycardia during programmed stimulation.

In group A, TWA outcome was determinate in 45 subjects (94%) and indeterminate in 3 cases for ECG tracing was obscured by noise. In group B, TWA test was positive in 5 (15%) symptomatic subjects, indeterminate or borderline for 3 (9%) subjects, and negative for the rest of them (76%). 24/25 negative TWA-test subjects were negative in EPS too, apart one subject with a documented ventricular tachycardia episode in amiodarone treatment (false negative). Regarding positive TWA-test subjects: 3 (60%) were positive for ventricular tachycardia in EPS, one (20%) positive for severe atrial sustained tachyarrhythmias, one refused EPS. We were able to state a correct diagnosis of limphocitary myocarditis for only one positive subject, that showed both TWA and EPS negativity after recovering. For the other positive patients, we suppose a non-documentable micropathology. One of the 3 positive subjects became TWA negative in amiodarone therapy. The third positive subject received an implantable cardioverter-defibrillator.

In conclusion, microvolt TWA study seems to be a useful, non-invasive and feasibility tool to evaluate arrhythmic risk in sporting population. TWA-test showed a high negative predictive value, whereas positive predictive value needs more data to confirm good concordance with EPS.

Table I:

81 athletes