Clinical Utility of Cardiopulmonary Exercise Testing in Patients with Heart Failure with Preserved Ejection Fraction

Dr Corrà and colleagues review the prognostic role of cardiopulmonary exercise testing (CPET) in heart failure (HF) and consider individual patient characteristics, the modality of CPET execution, and newer clinical endpoints.1 Given the lack of well-evidenced information relevant to clinical prediction in particular subsets of the HF population [elderly people, women, obese patients, patients with HF with preserved ejection fraction (HFpEF), etc.], the proposed prognostic flowcharts based on CPET parameters are greatly appreciated and may be regarded as representing an excellent starting point for further research. In our opinion, there are some issues in patients with HFpEF that warrant further comment. It is a heterogeneous syndrome that is especially common in elderly people, women and patients with high numbers of co-morbidities. The incidence and prevalence of HFpEF are increasing and the financial burdens imposed by recurrent admissions have become alarming.2, 3 This work1 highlights the utility of CPET as a tool for improving risk stratification using objective and functional parameters; however, information about the utility of CPET in HFpEF is scarce and in many cases is biased. For instance, risk stratification of patients with HFpEF is based on previous studies that have assessed the prognostic value (in terms of time to first cardiac-related mortality or hospitalization and/or cardiac transplantation) of CPET parameters [peak oxygen consumption (peak VO2), ventilatory efficiency, exertional oscillatory ventilation and percentage of predicted peak VO2 (pp-peak VO2)] in patients with HF and diastolic dysfunction. However, patient characteristics (predominantly male and aged <70 years) and outcomes differ from those seen in HFpEF patients in daily clinical practice.2, 3 Interestingly, our group recently published the results of a prospective study in which we evaluated the prognostic utility of pp-peak VO2 for predicting recurrent hospitalization in a cohort of elderly (mean ± standard deviation age: 72.5 ± 9.1 years), predominantly female (53%) and highly symptomatic patients with HFpEF.4 We found pp-peak VO2 was independently and linearly associated with recurrent admissions in this sample. In fact, a 10% reduction in pp-peak VO2 was associated with a 32% increase in risk for recurrent hospitalization.4 We believe these findings constitute valuable data supporting the application of CPET in HFpEF, in which there are still many gaps in knowledge.5 Additionally, we believe the incorporation of CPET assessment in the routine workup of patients with HFpEF may confer additional advantages such as: (i) better understanding of the pathophysiology of this complex syndrome; (ii) characterization of the different phenotypes of the syndrome, and (iii) evaluation of the effects of new therapeutic options. In conclusion, we acknowledge the relevance of Corrà et al.'s review1 for clinical practice, but, at the same time, we hope further studies will help to better characterize the utility of CPET in the risk assessment and management of real-world patients with HFpEF. Additionally, in further prognostic studies of CPET in HF, we strongly recommend that risk for recurrent hospitalization should be analysed as a clinical endpoint and that peak VO2 should be expressed as a percentage of age-, body mass index- and sex-predicted peak VO2 equations in order to facilitate more accurate risk stratification across the whole spectrum of patients with HF.