Prognostic role of cardiac power index in ambulatory patients with advanced heart failure

Abstract

BackgroundCardiac pump function is often quantified by left ventricular ejection fraction by various imaging modalities. As the heart is commonly conceptualized as a hydraulic pump, cardiac power describes the hydraulic function of the heart. We aim to describe the prognostic value of resting cardiac power index (CPI) in ambulatory patients with advanced heart failure. Methods and resultsWe calculated CPI in 495 sequential ambulatory patients with advanced heart failure who underwent invasive haemodynamic assessment with longitudinal follow-up of adverse outcomes (all-cause mortality, cardiac transplantation, or ventricular assist device placement). The median CPI was 0.44W/m(2) (interquartile range 0.37, 0.52). Over a median of 3.3years, there were 117 deaths, 104 transplants, and 20 ventricular assist device placements in our cohort. Diminished CPI (<0.44W/m(2)) was associated with increased adverse outcomes [hazard ratio (HR) 2.4, 95% confidence interval (CI) 1.8-3.1, P<0.0001). The prognostic value of CPI remained significant after adjustment for age, gender, pulmonary capillary wedge pressure, cardiac index, pulmonary vascular resistance, left ventricular ejection fraction, and creatinine [HR 1.5, 95% CI 1.03-2.3, P=0.04). Furthermore, CPI can risk stratify independently of peak oxygen consumption (HR 2.2, 95% CI 1.4-3.4, P=0.0003). ConclusionResting cardiac power index provides independent and incremental prediction in adverse outcomes beyond traditional haemodynamic and cardio-renal risk factors.