Sudden cardiac death risk factors in patients with heart failure treated with carvedilol

Background: Chronic heart failure (CHF) is associated with a high risk of sudden cardiac death (SCID). Most frequently SCID occurs in patients with NYHA class II and III. Aim: To evaluate the influence of prolonged carvedilol therapy on SCID risk in CHF patients. Methods: The study included 86 patients (81 men and 5 women) aged 56.8 +/- 9.19 (35-70) years with CHF in NYHA class II and III receiving an ACE inhibitor and diuretics but not beta-blockers. At baseline and after 12 months of carvedilol therapy the following risk factors for SCID were analysed: in angiography - occluded infarct-related artery; in echocardiography - left ventricular ejection fraction (LVEF) < 30%, volume of the left ventricle (LVEDV) > 140 ml; in ECG at rest - sinus heart rate (HRs) > 75/min, sustained atrial fibrillation, increased QTc; in 24-hour ECG recording - complex arrhythmia, blunted heart rate variability (SDNN < 100 ms) and abnormal turbulence parameters (TO and TS or one of them); in signal-averaged ECG - late ventricular potentials and prolonged QRS > 114 ms. The analysis of SCD risk factors in basic examination in patients who suddenly died was also performed. Results: During one-year carvedilol therapy heart transplantation was performed in 2 patients; 5 patients died. At 12 months the following risk factors for SCID were significantly changed: HRs > 75/min (50 vs. 16 patients, p=0.006), LVEF < 30% (37 vs. 14 patients, p=0.01), SDNN < 100 ms (19 vs. 9 patients, p=0.04). At 12 months the number of risk factors for SCD in each patient was significantly reduced (p=0.001). In patients who suddenly died we found a greater amount of SCID risk factors in basic examination (7 vs. 5) as compared to alive patients. Conclusions: Prolonged beta-adrenergic blockade reduces risk of sudden cardiac death through significant LVEF increase, reduction of HR at rest and improvement of HRV.