Abstract 17257: Stroke Volume Reserve Index in HFrEF: A Non-Invasive Predictor of Early Clinical Outcomes and Marker of Inotropic Reserve

Abstract

Introduction: We investigated whether stroke volume reserve index (SVRI), a novel non-invasive measure of inotropic reserve at submaximal exercise, would predict 1-year mortality and need for advanced therapies in heart-failure with reduced ejection fraction (HFrEF) patients. Methods: We retrospectively studied a consecutive series of 245 ambulatory patients (57±11 years, 84% men) with HFrEF at a single center who underwent cardiopulmonary exercise testing (CPET) from January 2013 to December 2018. The primary outcome was defined as heart-transplantation, urgent left ventricular assist device (LVAD) implantation or death within 1 year of evaluation. SVRI was estimated at rest and at anaerobic threshold by VO 2 (oxygen consumption)/pulse and previously validated estimates of C[a-v]O 2 (arteriovenous difference in oxygen content). Multivariate regression selected the optimal predictors. Results: Among HFrEF patients studied, 82 (33.5%) deteriorated: 34 required heart-transplantation, 20 required LVADs and 28 died. SVRI of less than 130% was the best predictor of clinical deterioration (OR 3.98, p<0.005), followed by cardiac index of less than 2 L/min/m 2 (OR 3.74, p<0.005), and peak VO 2 below the International Society for Heart and Lung Transplantation (ISHLT) cut-off (OR 3.01, p=0.008). Kaplan-Meier curves showed that 1-year event-free survival was significantly better amongst patients with normal SVRI, compared to patients with impaired inotropic reserve. Notably, HFrEF patients with an abnormal SVRI had a poor 1-year prognosis regardless of their peak VO 2 . Conclusions: SVRI is a non-invasive measurement that provides a measure of inotropic reserve at submaximal exercise, provides valuable prognostic information independent of other known and validated CPET parameters, and may predict deterioration in HFrEF patients more accurately than currently recommended CPET predictors. SVRI and peak VO 2 provide complementary prognostic information.