1Universitätsklinikum Münster Klinik für Kardiologie II - Rhythmologie Münster, Deutschland
Introduction: Implantable Cardioverter Defibrillators (ICD) are the cornerstone in ventricular arrhythmia (VT) treatment and sudden cardiac death (SCD) prevention. ICD shocks are associated with increased mortality and decreased quality of life. Data on the effectiveness and safety of AAD as first- or second-line therapy in patients with heart failure and the choice of the right drug is very scarce. Therefore, we sought to (1) examine the safety profile of Class I AAD compared to Class III AAD in patients with reduced ejection fraction (LVEF), and (2) investigate if changes of AAD have any effect on the incidence of ICD shocks.
Methods and Results: Patients from our outpatient clinic were retrospectively screened for impaired LVEF < 50% as well as antiarrhythmic therapy due to a VT and the presence of an ICD with a total of 497 patients matching these criteria. Of these, 380 (76.5%) underwent a change of their AADs and 234 (47.1%) suffered from an ICD shock during a mean follow up of 2676.7±2128.6 days. Mean age was 61.7±15.8 years, BMI of 27.7 ±4.9 kg/m2 and LVEF of 37.6±15.2 kg/m2. Patients with Class III AAD suffered significantly more shocks than patients with Class I AAD (p< 0.001), also patients with changed AAD regimen from Class I AA drugs to a class III drug had a significantly higher risk for recurring ICD shocks (OR 2.080, CI 95% 1.06; 4.09; p= 0.034). Patients with Class III AAD had worse mean LVEF (35 ± 15.2 %) than with Class I AAD (37.6 ± 15.3%). The overall risk to suffer an ICD shock after AA drug regiment change was also significantly higher than in unchanged AA treatments (OR 78.58, CI 95%, 10.94; 564.1, p < 0.001).
Conclusion: We can conclude that there seems to be an increased incidence and risk for ICD shocks after changing the AAD compared to unchanged treatment most likely indicating more severe underlying heart disease. Surprisingly, even though only patients with impaired LV function were included most ICD shocks occurred under the treatment with amiodarone and least in the presence of flecainide.