Prognostic Significance of Peak Workload-to-Weight Ratio by Cardiopulmonary Exercise Testing in Chronic Heart Failure.

The prognostic impact of peak workload-to-weight ratio (PWR) during cardiopulmonary exercise testing (CPET) and its determinants in patients with chronic heart failure (CHF) are not well understood. Consecutive 514 patients with CHF referred for CPET at the Hokkaido University Hospital between 2013 and 2018 were identified. The primary outcome was a composite of hospitalization because of worsening heart failure and death. PWR was calculated as peak workload normalized to body weight (W/kg) by CPET. Patients with low PWR (cut-off median 1.38 [W/kg], n = 257) were older and more anemic than those with high PWR (n = 257). In CPET, patients with low PWR displayed reduced peak oxygen consumption and impaired ventilatory efficiency compared with those with high PWR, whereas the peak respiratory exchange ratio was not significantly different between the 2 groups. There were 89 patients with events over a median follow-up period of 3.3 (interquartile range 0.8 to 5.5) years. The incidence of composite events was significantly higher in patients with low PWR than in those with high PWR (log-rank p <0.0001). In the multivariable Cox regression, lower PWR was associated with adverse events (hazard ratio 0.31, 95% confidence interval 0.13 to 0.73, p = 0.008). Low hemoglobin concentration was strongly related to impaired PWR (β coefficient = 0.43, per 1 g/100 ml increased, p <0.0001). In conclusion, PWR was associated with worse clinical outcomes, where blood hemoglobin was strongly related to PWR. Further study is required to identify therapies targeting peak workload achievements in exercise stress tests to improve the outcome in patients with CHF.