Prognostische Wertigkeit des T-Wellen-Alternans bei Patienten mit Erstimplantation eines implantierbaren Kardioverter-Defibrillators

Abstract

Background: The majority of sudden cardiac deaths (SCD) are caused by ventricular (malignant) tachyarrhythmias. An implantable cardioverter-defibrillator (ICD) is a well-established device for primary and secondary prevention of sudden cardiac death. Identifying patients at highest risk for SCD is a challenging task of modern cardiology. There are already well-known risk factors e.g. structural heart failures. Current risk stratification for predicting major arrhythmic is based on invasive and non-invasive apparatus-based diagnostic methods. The microvolt T-wave alternans (MTWA) test is a non-invasive treadmill test which predictive value to identify risk patient for SCD is still uncertain. Objectives: The aim of this clinical trial was to determine the predictive value of MTWA for malignant ventricular tachyarrhythmias and all-cause mortality in an unselected, consecutive cohort of patients who underwent first-time ICD implantation. Methods and Results: A total of 134 patients (mean age 64 years, mean left ventricular ejection fraction 31 %, 79 % male) who got first-time implanted ICD for primary or secondary prevention underwent a MTWA test shortly before or few days after the intervention in addition to common recommended risk stratification methods. However, indications for implantations were confirmed on present evidence-based guidelines. Over one-half (52 %) of patients had a negative MTWA test. A positive test was observed in 37 %. The remaining patients (11 %) had a so called “indeterminate” test result. Positive and indeterminate tests were subsumed under “non-negative” (63 %). Hence, it was possible to consider individual analysis (positive vs. negative vs. indeterminate) and a dichotomous group analysis (“non-negative” vs. “negative”). During follow-up (mean follow-up 12 months) there were eight deaths and three patients received an appropriate ICD shock. All patients with appropriate ICD shock had an indeterminate test result. Three deceased patients were tested negative; two had an indeterminate result and three patients had a positive MTWA test. The analysis showed that those individuals with an indeterminate test result had a significantly increased risk for incident appropriate ICD shock (p = 0,007). However, there was no significant difference among the dichotomous group analysis (non-negative vs. negative). Conclusions: The findings indicate that an indeterminate MTWA test is a significant prognostic value on the occurrence of appropriate ICD shock in candidates for an ICD.