Exercise postcapillary pulmonary hypertension in patients with chronic thromboembolism. Role of multimodal resting and exercise assessment

Abstract Introduction Chronic thromboembolic pulmonary disease refers to the presence of thrombotic material after a pulmonary embolism (PE), exercise limitation and the absence of resting pulmonary hypertension (PH) but impaired right ventricular and pulmonary vascular reserve during exercise causing exercise precapillary PH (exprecapPH). However, in some patients, PH arises from an abnormal increase in pulmonary arterial wedge pressure (PAWP) with exercise in relation to underlying diastolic dysfunction, with thrombotic material not playing a substantial role. Whether these patients present distinct non-invasive and resting invasive parameters remains largely unknown. Purpose To compare the different exercise hemodynamic profiles of patients with chronic thromboembolism to identify clinical, echocardiographic, functional and hemodynamic parameters associated with exercise postcapillary PH (expostcapPH). Methods Data come from a prospective cohort of 71 symptomatic patients with perfusion defects in lung scintigraphy and computed tomographic confirmation of chronic thrombi despite anticoagulation ≥3 months after PE without or mild resting PH, undergoing exercise cardiac catheterization via supine cycle ergometry. A multipoint mean pulmonary artery pressure (mPAP)/cardiac output (CO) and mean PAWP/CO slope were calculated. Simultaneous stress echocardiography was available in 43 patients. Cardiopulmonary exercise test (CPET) was performed 24 hours before catheterization. Results Mean age was 53±13.9 years, 46 (64.8%) were males. 37 patients showed normal exercise hemodynamics, while 26 developed exprecapPH and 8 expostcapPH. Mean mPAP/CO slope was 3.1±1.6 mmHg/L/min, mean PAWP/CO slope 1.5±0.9 mmHg/L/min. Patients with expostcapPH were older, had a higher body mass index and hypertension. Comparison of hemodynamics, CPET and resting echocardiography is depicted in the table. Patients with expostcapPH, similar to those without exercise PH, had significantly lower resting pulmonary pressures and pulmonary vascular resistance than those with exprecapPH. These differences remained at peak exercise; however, while resting PAWP did not differ between groups, a significant increase in PAWP was unmasked in patients with expostcapPH compared to the other groups, and accordingly a significant difference in the PAWP/CO slope. Regarding CPET, patients with expostcapPH had higher baseline systolic blood pressure and lower functional capacity (VO2 max, VO2 at VT1, O2 pulse, OUES). Resting TAPSE/PASP was higher in patients with expostcapPH compared to those with exprecapPH. Conclusions Patients with chronic thromboembolism and expostcapPH exhibit distinct clinical features and have lower functional capacity, while resting PAWP did not allow differentiation between groups. Further studies are warranted to delineate characteristic elements of patients with underlying diastolic dysfunction due to its distinct prognosis and treatment.