Influence of intracardiac pressure on spontaneous ventricular arrhythmias in patients with systolic heart failure: Insights from the REDUCEhf trial

Background-The implantation of a combination hemodynamic monitor-cardioverter-defibrillator in the Reducing Decompensation Events Utilizing Intracardiac Pressures in Patients with Chronic Heart Failure (REDUCEhf) study allowed assessment of the relationship between daily intracardiac pressure and occurrence of ventricular arrhythmic (VT/VF) events. Methods and Results-Median estimated pulmonary artery diastolic pressures (ePAD) were calculated every 24 hours in 378 subjects with New York Heart Association functional class II-III heart failure who had at least 60 days of hemodynamic data. Forty-six subjects experienced 140 VT/VF events on 80 unique study days in which daily median ePAD was available. The incidence of days with VT/VF events was significantly higher when the daily median ePAD for a subject was elevated, defined as >1 SD above that subject's average median ePAD for the whole study: (2.8 episode days per patient-year compared with 1.7 episode days per patient-year; P=0.040). However, the incidence of days with VT/VF events was not significantly different on days when ePAD was >25 mm Hg compared with days when ePAD was <25 mm Hg. For all 378 subjects, the risk of VT/VF increased with average median ePAD calculated over the whole follow-up period (odds ratio, 1.072 for a 1-mm Hg increase; 95% confidence interval, 1.023-1.124; P=0.003). Conclusions-There is significant positive association between average daily median ePAD and risk for VT/VF. Among patients with VT/VF, elevated intracardiac pressures are associated with higher VT/VF risk only when the definition of increased pressure is subject specific.