Feasibility of T-wave alternans testing in patients considered for a cardioverter-defibrillator implantation

Dear Sir,

The contribution by Kraaier et al. published in this Journal and just listed in PubMed, deals with a very practical matter, i.e., that of the feasibility of T-wave alternans (TWA) testing in patients with cardiomyopathy considered for a cardioverter-defibrillator (ICD) implantation [1]. The authors did a retrospective analysis of the records of 165 patients who had an ICD implanted for primary prevention of sudden cardiac death, and found that 35% of them had one or more reasons to waiver TWA testing because of atrial fibrillation or flutter, pacemaker dependency, recent (cardiovascular) surgery (<1 month), and inability to exercise, and thus they concluded that TWA testing should be evaluated employing an alternative to the exercise method. In the recently published PREVENT-SCD study [2] a remarkably similar percentage (38%) of the 453 studied patients, i.e., 65 patients, could not undergo TWA testing for the same reasons as listed in the study by Kraaier et al [1]. Also the authors of the PREVENT-SCD reported a novel finding, i.e. that patients ineligible to undergo TWA testing had the highest risk for lethal ventricular arrhythmias at follow-up [2]. Consequently it will be important for Kraaier et al. to provide follow-up information on the outcome of their patients who were ineligible to undergo TWA testing.