Impact of right ventricular contractile reserve during low-load exercise on exercise intolerance in heart failure.

Kinoshita M; Inoue K; Higashi H; Akazawa Y; Sasaki Y; Fujii A; Uetani T; Inaba S; Aono J; Nagai T; Nishimura K; Ikeda S; Yamaguchi O

ESC heart failure [ESC Heart Fail], ISSN: 2055-5822, 2020 Sep 13; Publisher: John Wiley & Sons Ltd on behalf of the European Society of Cardiology; PMID: 32924319

Aims: Traditional criteria for heart transplantation by cardiopulmonary exercise testing (CPX) include peak oxygen uptake (VO 2 ) < 14 mL/kg/min. Reaching a sufficient exercise load is challenging for patients with refractory heart failure (HF) because of their exercise intolerance. Recently, a substantial impact of right ventricular (RV) dysfunction was highlighted on urgent heart transplantation and mortality. This study aims to investigate the impact of RV contractile reserve, assessed by low-load exercise stress echocardiography (ESE), on exercise intolerance defined as peak VO 2  < 14 mL/kg/min, in patients with HF.
Methods and Results: We prospectively examined 67 consecutive patients hospitalized for HF who underwent ESE and CPX under a stabilized HF condition. Although low-load ESE was defined as 25 W load exercise, an increment in RV systolic (s’) velocity was regarded as the preservation of RV contractile reserve. All patients completed low-load ESE. During low-load ESE, the variation in RV s’ velocity significantly correlated with peak VO 2 (r = 0.787, P < 0.001). The change in RV s’ velocity during low-load ESE accurately identified patients with peak VO 2  < 14 mL/kg/min (area under the curve, 0.95; sensitivity, 92%; specificity, 85%). The intraclass correlation coefficient for intra-observer and inter-observer agreement for the change in RV s’ velocity was 0.96 (95% confidence interval, 0.88-0.99, P < 0.001) and 0.86 (95% confidence interval, 0.64-0.95, P < 0.001), respectively. The RV-to-pulmonary circulation (PC) coupling, which was assessed by the slope of the relationship between RV s’ velocity and pulmonary artery systolic pressure at rest and low-load exercise, was worse in the low-peak VO 2 group (<14 mL/kg/min) than the preserved-peak VO 2 group (≥14 mL/kg/min).
Conclusions: The change in RV s’ velocity during low-load ESE could estimate the exercise capacity in HF patients. The assessments of RV contractile reserve and RV-to-PC coupling could be clinically beneficial to distinguish high-risk HF patients.