Chronic thromboembolic and pulmonary arterial hypertension share right ventricular and pulmonary artery CMR features

BACKGROUND

Cardiac magnetic resonance (CMR) imaging has gained importance in pulmonary hypertension (PH) and studies have demonstrated its use as a surrogate marker and in following treatment of these patients. The pathophysiology of PH differs between pulmonary arterial hypertension (PAH, group 1) and chronic thromboembolic PH (CTEPH, group 4).

OBJECTIVES

The present study tested the hypothesis that PAH and CTEPH display different characteristics on CMR imaging.

METHODS

46 patients were evaluated for pulmonary vascular disease in the French National Reference Center for PH (23 PAH and 23 CTEPH matched for age and gender). All patients had the right heart catheterization (RHC) and CMR imaging performed within 48h. CMR imaging was performed on a 1.5 T scanner.

RESULTS

PAH and CTEPH had similar body surface area and similar invasive hemodynamics, including mean pulmonary arterial pressure, cardiac index, pulmonary vascular resistance and right atrial pressure. PAH and CTEPH had similar CMR data. Right ventricular (RV) morphology and function and pulmonary artery (PA) data were also similar.

CONCLUSION

Age- and sex-matched PAH and CTEPH patients displayed similar values of the CMR indices of RV and PA morphology and function, suggesting that the RV-PA responses are similar in both groups, mostly related to the overall increase in after load.

The association between resting and mild-to-moderate exercise pulmonary artery pressure

The mean pulmonary artery pressure (P(pa)) achieved on mild-to-moderate exercise is age related and its haemodynamic correlates remain to be documented in patients free of pulmonary hypertension (PH). Our retrospective study involved patients free of PH investigated in our centre for possible pulmonary vascular disease between January 1, 2007 and October 31, 2009 who underwent right heart catheterisation at rest and during supine exercise up to 60 W. The 38 out of 99 patients aged <50 yrs were included and a P(pa) of 30 mmHg was considered the upper limit of normal on exercise. The 24 subjects who developed P(pa)>30 mmHg on exercise had higher resting P(pa) (19±3 versus 15±4 mmHg) and indexed pulmonary vascular resistance (PVRi; 3.4±1.5 versus 2.2±1.1 WU·m(2); p<0.05) than the remaining 14 subjects. Resting P(pa) >15 mmHg predicted exercise P(pa) >30 mmHg with 88% sensitivity and 57% specificity. The eight patients with resting P(pa) 22-24 mmHg all had exercise P(pa) >30 mmHg. In subjects aged <50 yrs investigated for possible pulmonary vascular disease and free of PH, patients with mild-to-moderate exercise P(pa) >30 mmHg had higher resting PVRi and higher resting P(pa), although there was no resting P(pa) threshold value that could predict normal response on mild-to-moderate exercise. The clinical relevance of such findings deserves further long-term follow-up studies.