Pulmonary Hypertension Overlap Syndromes

Pulmonary Hypertension in Transcatheter Mitral Valve Repair for Secondary Mitral Regurgitation: The COAPT Trial

BACKGROUND

Pulmonary hypertension worsens prognosis in patients with heart failure (HF) and secondary mitral regurgitation (SMR).

OBJECTIVES

This study sought to determine whether baseline pulmonary hypertension influences outcomes of transcatheter mitral valve repair (TMVr) in patients with HF with SMR.

METHODS

In the COAPT (Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients with Functional Mitral Regurgitation) trial, 614 patients with HF with moderate-to-severe or severe SMR were randomized to TMVr with the MitraClip plus guideline-directed medical therapy (GDMT) (n = 302) versus GDMT alone (n = 312). Baseline pulmonary artery systolic pressure (PASP) estimated from echocardiography was categorized as substantially increased (≥50 mm Hg) versus not substantially increased (<50 mm Hg).

RESULTS

Among 528 patients, 184 (82 TMVr, 102 GDMT) had PASP of ≥50 mm Hg (mean: 59.1 ± 8.8 mm Hg) and 344 (171 TMVr, 173 GDMT) had PASP of <50 mm Hg (mean: 36.3 ± 8.1 mm Hg). Patients with PASP of ≥50 mm Hg had higher 2-year rates of death or HF hospitalization (HFH) compared to those with PASP of <50 mm Hg (68.8% vs. 49.1%; adjusted hazard ratio: 1.52; 95% confidence interval: 1.17 to 1.97; p = 0.002). Rates of death or HFH were reduced by TMVr versus GDMT alone, irrespective of baseline PASP (p_interaction = 0.45). TMVr reduced PASP from baseline to 30 days to a greater than GDMT alone (adjusted least squares mean: -4.0 vs. -0.9 mm Hg; p = 0.006), a change that was associated with reduced risk of death or HFH between 30 days and 2 years (adjusted hazard ratio: 0.91 per -5 mm Hg PASP; 95% confidence interval: 0.86 to 0.96; p = 0.0009).

CONCLUSIONS

Elevated PASP is associated with a worse prognosis in patients with HF with severe SMR. TMVr with the MitraClip reduced 30-day PASP and 2-year rates of death or HFH compared with GDMT alone, irrespective of PASP.

The beneficial effects of angiotensin-converting enzyme II (ACE2) activator in pulmonary hypertension secondary to left ventricular dysfunction

Pulmonary hypertension (PH) is a lethal and rapidly progressing disorder if left untreated, but there is still no definitive therapy. An imbalance between vasoconstriction and vasodilation has been proposed as the mechanism underlying PH. Among the vasomediators of the pulmonary circulation is the renin-angiotensin system (RAS), the involvement of which in the development of PH has been proposed. Within the RAS, angiotensin-converting enzyme 2 (ACE2), which converts angiotensin (Ang) II into Ang-(1-7), is an important regulator of blood pressure, and has been implicated in cardiovascular disease and PH. In this study, we investigated the effects of the ACE2 activator diminazene aceturate (DIZE) on the development of PH secondary to left ventricular dysfunction. A model of PH secondary to left ventricular dysfunction was established in 6-week-old Wistar rats by ascending aortic banding for 42 days. The hemodynamics and pulmonary expression of ACE, Ang II, ACE2, Ang-(1-7), and the Ang-(1-7) MAS receptor were investigated in the early treatment group, which was administered DIZE (15 mg/kg/day) from days 1 to 42, and in the late treatment group, administered DIZE (15 mg/kg/day) from days 29 to 42. Sham-operated rats served as controls. DIZE ameliorated mean pulmonary artery pressure, pulmonary arteriolar remodeling, and plasma brain natriuretic peptide levels, in addition to reversing the overexpression of ACE and up-regulation of both Ang-(1-7) and MAS, in the early and late treatment groups. DIZE has therapeutic potential for preventing the development of PH secondary to left ventricular dysfunction through ACEII activation and the positive feedback of ANG-(1-7) on the MAS receptor. A translational study in humans is needed to substantiate these findings.