title: The power of exercise-induced T-wave alternans to predict ventricular arrhythmias in patients with implanted cardiac defibrillator.
abstract: The power of exercise-induced T-wave alternans (TWA) to predict the occurrence of ventricular arrhythmias was evaluated in 67 patients with an implanted cardiac defibrillator (ICD). During the 4-year follow-up, electrocardiographic (ECG) tracings were recorded in a bicycle ergometer test with increasing workload ranging from zero (NoWL) to the patient's maximal capacity (MaxWL). After the follow-up, patients were classified as either ICD_Cases (n = 29), if developed ventricular tachycardia/fibrillation, or ICD_Controls (n = 38). TWA was quantified using our heart-rate adaptive match filter. Compared to NoWL, MaxWL was characterized by faster heart rates and higher TWA in both ICD_Cases (12-18 μ V vs. 20-39 μ V; P < 0.05) and ICD_Controls (9-15 μ V vs. 20-32 μ V; P < 0.05). Still, TWA was able to discriminate the two ICD groups during NoWL (sensitivity = 59-83%, specificity = 53-84%) but not MaxWL (sensitivity = 55-69%, specificity = 39-74%). Thus, this retrospective observational case-control study suggests that TWA's predictive power for the occurrence of ventricular arrhythmias could increase at low heart rates.
authors.affiliation: Department of Information Engineering, Polytechnic University of Marche, Ancona, Italy. l.burattini@univpm.it
authors.forename: Laura
authors.initials: L
authors.lastname: Burattini
authors.forename: Sumche
authors.initials: S
authors.lastname: Man
authors.forename: Cees A
authors.initials: CA
authors.lastname: Sweene
mesh_terms: D000465:Algorithms; D017147:Defibrillators, Implantable; D003936:Diagnosis, Computer-Assisted / Q000379:methods; D004562:Electrocardiography / Q000379:methods*; D005080:Exercise Test / Q000379:methods*; D006801:Humans; D015203:Reproducibility of Results; D055502:Secondary Prevention; D012680:Sensitivity and Specificity; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000517:prevention & control*; D014693:Ventricular Fibrillation / Q000175:diagnosis* / Q000517:prevention & control*