Feasibility of exercise stress echocardiography for detecting exercise-induced pulmonary hypertension in patients after pulmonary embolism

Introduction The prognostic significance of exercise-induced pulmonary hypertension (ePH) following pulmonary embolism (PE) has not yet been fully established. Non-invasive diagnosis of ePH typically relies on measuring peak tricuspid regurgitation velocity (TRV) during exercise stress echocardiography (ESE). Obtaining reliable measurements at high workloads can be challenging due to technical limitations or early muscular fatigue. In patients with heart failure with preserved ejection fraction (HFpEF), a marked increase in pulmonary pressures has been observed even at lower exercise intensities. Purpose To assess whether the pulmonary pressure increase characteristic of ePH can be detected at lower exercise workloads. Methods We enrolled patients with a history of PE who had completed at least three months of oral anticoagulant therapy and had no evidence of resting pulmonary hypertension (PH). In the absence of measurable tricuspid regurgitation (TR) at rest, PH probability was evaluated using right ventricular outflow tract acceleration time and other echocardiographic signs suggestive of PH. All participants underwent semi-supine bicycle ESE following the World Health Organization (WHO) protocol. Echocardiographic measurements were obtained at rest, at 50 Watts, and peak exercise. A TRV ≥ 3.5 m/s was used as the diagnostic threshold for ePH. Results A total of 47 patients (mean age 58.34 ± 13.56 years; 57.45% male) underwent ESE, reaching 82.00 ± 10.54% of the age-predicted maximal heart rate. TR was detectable at rest and 50 Watts in 68.09% of patients, and 91.49% at peak stress. TRV increased significantly with exercise workload (rest: 2.02 ± 0.57 m/s; 50 W: 2.24 ± 0.71 m/s; peak: 2.67 ± 0.76 m/s; p < 0.001). The prevalence of ePH was 4.26% at 50 Watts, increasing to 27.66% at peak stress. The difference in detection rates between 50 Watts and peak exercise was statistically significant (McNemar test, p = 0.016). Conclusion While TRV increases significantly even at low exercise intensities, achieving a submaximal heart rate substantially improves the sensitivity of ePH detection. Premature termination of the stress test may result in underdiagnosis of ePH in patients after PE.