Phenotypic Characterization of Heart Failure with Preserved Ejection Fraction. Letter Regarding the Article ‘Disproportionate Exercise-Induced Pulmonary Hypertension in Relation to Cardiac Output in Heart Failure with Preserved Ejection Fraction: A Non-Invasive Echocardiographic Study’

I read the recently published article by Saito et al.1 with great enthusiasm. The authors reported covert pulmonary vascular disease (PVD) by demonstrating disproportionate exercise-induced pulmonary hypertension (DEi-PH) as a distinct phenotype of heart failure with preserved ejection fraction (HFpEF). The DEi-PH was defined using mean pulmonary artery pressure (MPAP)/cardiac output (CO) slope >5.2 mmHg/L/min. Nevertheless, peak exercise haemodynamic parameters revealed several interesting echocardiographic changes that could offer several alternative interpretations. Pulmonary capillary wedge pressure (PCWP) can be easily obtained from the Nagueh formula (1.24x E/e' + 1.9).2 Similar to MPAP or pulmonary artery systolic pressure (PASP), PCWP rose during exercise to 23.2 and 22.85 mmHg in patients without DEi-PH and with DEi-PH, respectively. A comparable increase in PCWP despite 1.9 L/min lesser rise in CO (5.7 L/min vs. 7.6 L/min) in patients with DEi-PH also deserves attention and explanations.3 The derived PCWP/CO slope value in HFpEF with DEi-PH and HFpEF without DEi-PH was 1.82 and 1.13, respectively (Figure 1). Therefore, like a disproportionate rise in MPAP compared to CO during exercise can reveal underlying PVD, disproportionate rise in PCWP compared to CO can also reveal underlying left ventricular dysfunction and/or poor left atrial compliance.