Introduction: Patients with left ventricular ejection fraction (LVEF) ≤ 35% are eligible for implantable cardioverter-defibrillator (ICD) placement in the primary prevention of sudden cardiac death. Nevertheless, other risk factors facilitating the selection of individuals with highest mortality are still sought. The aim of the study was to verify the usefulness of microvolt T-wave alternans (MTWA) testing in the assessment of all-cause mortality and life-threatening ventricular arrhythmias (EVENTs) in these patients. Previous data from the literature are inconclusive.
Material and methods: Patients with LVEF ≤ 35% were eligible if they did not have a history of sustained ventricular arrhythmias, and were treated with β-blockers. Participants underwent MTWA testing and were subsequently followed.
Results: The group consisted of 139 patients. MTWA results were classified as non-negative (MTWA_non-neg) in 93 and negative (MTWA_neg) in 46 patients. During the 14.3 ±8.6 months of follow-up, EVENTs were observed in 21 patients. The 1-year EVENT rate was 16.4% among MTWA_non-neg patients, and 2.6% among MTWA_neg patients (p = 0.006). The sensitivity of the MTWA test was 95.24%, the specificity - 38.14%, the positive predictive value - 21.51% and the negative predictive value - 97.83%.
Conclusions: In the group of patients with left ventricular systolic dysfunction, with the exclusion of patients with the history of life-threatening ventricular arrhythmia and individuals not being on chronic β-adrenolytic therapy, the abnormal result of MTWA testing is associated with significantly increased risk of all-cause mortality and life-threatening ventricular arrhythmia during 1 year of follow-up, thus identifying the individuals at the highest risk.
Keywords: left ventricular dysfunction; microvolt T-wave alternans; prognosis.