Pathophysiological and prognostic relevance of exercise CMR-derived pulmonary artery compliance in patients with...

Right ventricular (RV) dysfunction has been associated with worse prognosis in patients with diastolic dysfunction, highlighting the importance of early detection. Main pulmonary artery (MPA) compliance may indicate adverse biventricular coupling prior to emerging RV function.

Sixty-eight patients with suspected diastolic dysfunction (New York Heart Association ≥ II, LV EF ≥ 50%, E/e' ≥ 8) were prospectively recruited and underwent rest and stress right heart catheterization, echocardiography, and cardiovascular magnetic resonance imaging (CMR) within 24 h. Maximum (A _max) and minimum (A _min) MPA vessel area and stroke volume (RVSV) were obtained from CMR real-time phase-contrast images at rest and during exercise stress. Compliance was calculated as pulsatility $\mathrm{MP}{A}_{\mathrm{Puls}}=\left(\frac{A_{\max }-A_{\min }}{A_{\min }}\right)\times 100$ and capacitance $\mathrm{MP}{A}_{\mathrm{Cap}}=\frac{\mathrm{MP}{A}_{\mathrm{Puls}}}{\mathrm{RVSV}}$ . Patients had systematic follow-up after 48 months. Occurrence of cardiovascular events was defined as the primary endpoint. A total of 63 patients [66 ± 9 years, 39 (61.9%) female] were eligible for final analyses. MPA_Puls and MPA_Cap were lower during exercise stress compared with rest (20% vs. 17.5%, P = 0.034 and 0.26%/mL vs. 0.20%/mL, P = 0.001). Subgroups with and without heart failure with preserved ejection fraction (HFpEF) had similar MPA compliance at rest, however, HFpEF patients had a steeper decrease of compliance during exercise stress (MPA_Puls 13% vs. 20%; P < 0.001 MPA_Cap 0.16%/mL vs. 0.25%/mL, P = 0.018). Decreasing MPA_Puls and MPA_Cap during exercise stress correlated with markers of diastolic dysfunction including pulmonary capillary wedge pressure, E/e', and HFA-PEFF score. Patients with decreased MPA_Puls (HR 6.0; P = 0.016) and MPA_Cap (HR 11.3; P = 0.015) had worse outcomes independent from conventional markers of diastolic dysfunction.

In patients with suspected diastolic dysfunction and preserved RV function, exercise-stress testing unmasked decreasing CMR-derived MPA compliance, associated with LV diastolic dysfunction and indicated higher risk for cardiovascular events.