Reduced long-term overall mortality in heart failure patients with prolonged QRS treated with CRT combined with ICD vs. heart failure patients with narrow QRS treated with ICD only.

AIMS: It is not known whether heart failure (HF) patients with prolonged QRS who undergo cardiac resynchronization therapy combined with a defibrillator (CRT-D) have a prognostic advantage over HF patients with narrow QRS (therefore without indication for CRT) treated with an implantable cardioverter defibrillator (ICD) only. The aim of this study was to compare the long-term mortality of a group of HF patients with prolonged QRS receiving CRT-D with that of a similar group of patients with narrow QRS receiving ICD only. METHODS AND RESULTS: A total of 312 patients (mean age 66 ± 13 years; 84% male, mean left ventricular ejection fraction 25 ± 4%, mean New York Heart Association class 2.6 ± 0.5) were included in the analysis. Of these, 138 with a QRS complex duration ≥120 ms received a CRT-D. During follow-up, the time and cause of death were assessed. During a median follow-up of 46 months, CRT-D patients showed significantly lower overall mortality (P = 0.038). Compared with patients receiving ICD only, CRT-D patients showed lower HF mortality (P = 0.003). Coronary mortality, non-cardiac mortality, and sudden mortality were similar in both groups (all P > 0.05). A positive response to CRT was an independent predictor of reduced mortality on multivariate analysis (hazard ratio: 0.27; P = 0.047). CONCLUSION: In HF patients treated with ICD, the subgroup of patients with prolonged QRS who receive CRT-D displays better long-term survival than narrow QRS ICD recipients, owing to their reduced HF mortality.

Relationship between seasonal weather changes, risk of dehydration, and incidence of severe bradyarrhythmias requiring urgent temporary transvenous cardiac pacing in an elderly population.

There is little information on any seasonal variations or meteorological factors associated with symptomatic bradyarrhythmias requiring cardiac pacing. The aim of this single-center study was to investigate the seasonal distribution of the incidence of severe, life-threatening bradyarrhythmias requiring urgent temporary transvenous cardiac pacing in an elderly population. Consecutive patients who underwent urgent temporary transvenous cardiac pacing between 2007 and 2012 were enrolled. The baseline characteristics of the patients and some meteorological parameters, including the calculation the daily heat index (HI), were recorded. During the study period, 79 consecutive patients (mean age 82 ± 8 years, 41% male) underwent urgent temporary transvenous cardiac pacing, mainly for third-degree atrioventricular block (79%). The incidence of bradyarrhythmias was significantly higher in summer than in the other seasons (P < 0.001). Moreover, the highest incidence was observed in months with HI > 90 °F for >3 h per day for at least 10 days (P < 0.001). A direct correlation was found between the average monthly temperature and the monthly number of patients undergoing temporary cardiac pacing (r = 0.54, P < 0.001). Compared with other patients, those observed during the hottest months were significantly older and more frequently affected by chronic disabling neurological diseases (all P < 0.05). In addition, they more frequently showed biochemical indices of dehydration, renal function impairment and hyperkalemia (all P < 0.05). This study showed an increased incidence of severe bradyarrhythmias in an elderly population during the hottest months of the year. In these months, in subjects characterized by increased susceptibility to dehydration, the risk of developing bradyarrhythmias was increased significantly.