Prognostic value of repeated peak oxygen uptake measurements in patients with a left ventricular assist device

Abstract

Background: Peak oxygen uptake (pVO₂) predicts mortality in patients with heart failure on left ventricular assist device (LVAD) support. This follow-up of the PRO-VAD study examines the prognostic value of repeated pVO₂ measurements during long-term follow-up.

Methods: This multicenter follow-up study included patients from the original PRO-VAD cohort who performed a cardiopulmonary exercise test (CPET) twice. Patients were categorized into 4 groups based on pVO₂ levels at the 2 CPETs: low at both tests, low at the first and high at the second test, high at the first and low at the second test, and high at both tests. Low pVO₂ was defined as ≤14 ml/kg/min (or ≤12 ml/kg/min if beta-blocker tolerant), while values above these thresholds were considered high. Survival outcomes were analyzed using the Kaplan-Meier method and cause-specific Cox analysis.

Results: The study included 152 patients with repeated CPETs at approximately 6 and 12 months following LVAD implantation. The cohort showed slight but significant pVO₂ improvement (median change: 0.4 ml/kg/min, p = 0.04). Persistently high pVO₂ (76 patients) was associated with a 5-fold reduction in mortality hazard (hazard ratio [HR] 0.20, p = 0.002), compared with persistently low pVO₂ (46 patients). Improvement from low to high pVO₂ (21 patients) displayed similar benefits (HR 0.21, p = 0.02).

Conclusions: pVO₂ measurements remain predictive of mortality upon reiteration in patients with LVAD, with changes in pVO₂ providing additional prognostic value in identifying patients with an excellent outcome on ongoing LVAD support and in identifying patients requiring further interventions.

Keywords: left ventricular assist devices; pVO(2); peak oxygen uptake; prognosis; repeated cardiopulmonary exercise testing.