Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients With Functional Mitral Regurgitation - COAPT
Dharam J. Kumbhani

Description of the COAPT Trial

Study Design

Patients with HF and grade 3-4+ MR who remained symptomatic despite maximally tolerated guideline-directed medical therapy (GDMT) were randomized to MitraClip + GDMT (n = 302) vs. GDMT alone (n = 312). This trial had an open-label design.

• - Total number of enrollees: 614
• - Duration of follow-up: 24 months
• - Mean patient age: 72 years
• - Percentage female: 37%

Inclusion criteria

• - Ischemic or nonischemic cardiomyopathy with left ventricular ejection fraction (LVEF) 20%-50% and LV end-systolic dimension (LVESD) ≤70 mm
• - Moderate-to-severe (3+) or severe (4+) secondary MR confirmed by an independent echocardiographic core laboratory prior to enrollment (US American Society of Echocardiography criteria)
• - New York Heart Association (NYHA) functional class II-IVa (ambulatory) despite a stable maximally tolerated GDMT regimen and cardiac resynchronization therapy (CRT) (if appropriate), per     societal guidelines
• - Patient has had ≥1 HF hospitalization within 12 months and/or a B-type natriuretic peptide (BNP) ≥300 pg/ml or a NT-proBNP ≥1500 pg/ml
• - Not appropriate for mitral valve surgery by local heart team assessment
• - Interventional cardiologist believes secondary MR can be successfully treated by the MitraClip

Exclusion criteria

• - American College of Cardiology/American Heart Association stage D HF, hemodynamic instability, or cardiogenic shock
• - Untreated clinically significant coronary artery disease requiring revascularization
• - Chronic obstructive pulmonary disease (COPD) requiring continuous home oxygen or chronic oral steroid use
• - Severe pulmonary hypertension or moderate or severe right ventricular dysfunction
• - Aortic or tricuspid valve disease requiring surgery or transcatheter intervention
• - Mitral valve orifice area <4.0 cm2 by site-assessed transthoracic echocardiography
• - Life expectancy <12 months due to noncardiac conditions

Other salient features/characteristics

• - Prior myocardial infarction: 51%, prior percutaneous coronary intervention: 46%, prior coronary artery bypass grafting: 40%, COPD: 23%
• - Society of Thoracic Surgeons Predicted Risk of Mortality score (STS PROM) for replacement: 8.1%, ≥8%: 42%
• - High surgical risk: 69%
• - Ischemic HF: 61%
• - HF hospitalization within 1 year: 57%
• - Prior CRT: 36%
• - Echo (mean): effective regurgitant orifice area (EROA): 0.41 cm2, LVESD: 53 mm, LV end-diastolic dimension: 62 mm, LVEF: 31.3%, tricuspid regurgitation ≥2+: 16%
• - Beta-blockers: 91%, angiotensin-converting enzyme inhibitor/angiotensin-receptor blocker/angiotensin receptor–neprilysin inhibitor: 66%, mineralocorticoid receptor antagonist: 50%

Principal Findings

The primary effectiveness endpoint, HF hospitalization at 24 months for MitraClip + GDMT vs. GDMT, was 35.8% vs. 67.9% (hazard ratio [HR] 0.53, 95% confidence interval [CI] 0.40-0.70, p < 0.001). The primary safety endpoint, freedom from device-related complications at 12 months, was 96.6% for MitraClip (p < 0.001).

Secondary outcomes for MitraClip + GDMT vs. GDMT

• - All-cause mortality: 29.1% vs. 46.1%, HR 0.62, 95% CI 0.46-0.82, p < 0.001
• - Death or HF hospitalization: 45.7% vs. 67.9%, p < 0.001
• - Cardiovascular death: 29.1% vs. 46.1%, p < 0.001
• - Stroke: 4.4% vs. 5.1%, p = 0.93
• - LV assist device (LVAD) or heart transplant: 4.4% vs. 9.5%, p = 0.01
• - Mean change in LV end-diastolic volume (LVEDV) at 1 year compared with baseline: -3.7 vs. 17.1 mm
• - MR severity ≤2% at 24 months: 99.1% vs. 43.4%, p < 0.001
• - MR severity improved by ≥2 grades: 84.1% vs. 15.9%, p < 0.0001
• - Tricuspid regurgitation severity worsened: 17.7% vs. 16.1%, p = 0.34
• - On echo subanalysis, it appeared that PISA and hemodynamics after MitraClip had limitations, while color Doppler, pulmonary vein flow, and vena contracta were more reliable to assess residual MR.

Quality-of-life (QoL) subanalysis

Mean Kansas City Cardiomyopathy Questionnaire (KCCQ)-OS (overall summary) at baseline for MitraClip + GDMT vs. GDMT: 53.2 vs. 51.6; mean KCCQ-QoL: 45.2 vs. 44.7

• - At 24 months, mean KCCQ-OS: 70.9 vs. 61.2, p < 0.01; mean KCCQ-QoL: 71.6 vs. 58.5, p < 0.05
• - Alive and moderately improved at 24 months: 36.4% vs. 16.6%, p < 0.001
• - Alive and substantially improved at 24 months: 29.1% vs. 11.7%, p < 0.001

Three-year outcomes

At 2 years, patients in the GDMT arm could cross over to the MitraClip arm if needed. As a result, total crossover was 18.6% (majority between 2 and 3 years). For the primary results, on ITT, there was still a profound benefit of MitraClip + GDMT over GDMT (annualized rates 35.5% vs. 68.8%, HR 0.49, 95% CI 0.37-0.63, p < 0.001). Benefit of MitraClip on mortality was preserved (42.8% vs. 55.5%, p = 0.001). Among the MitraClip patients, progressive HF requiring LVAD or heart transplant occurred in an additional 3.6% of patients (total 7.4%). Among the patients who crossed over, first HF hospitalization at 1 year was lower (13.8%), and the curves for the other clinical endpoints were more similar to the MitraClip arm than to the GDMT only arm, suggesting that benefit noted for the original MitraClip arm could be replicated in the control arm with MitraClip implantation (crossover).

Interpretation of the COAPT Trial

The results of this landmark trial indicate that transcatheter mitral valve approximation using the MitraClip on a background of maximally tolerated GDMT was superior to GDMT alone in reducing HF hospitalization and mortality in symptomatic HF patients with grade 3-4+ MR. Improvements were also observed in LV dimensions and patient symptoms. Significant improvements were noted in QoL measurements starting at 1 month and sustained out to 24 months. The device had excellent safety.

All operators in this trial were experienced in the use of MitraClip. These results come on the heels of the recently published MITRA-FR trial, which did not show a benefit in this patient population. Possible reasons for differences include enrollment of patients with more severe MR (EROA >30 in COAPT vs. >20 in MITRA-FR) and less dilated ventricles (LVEDV 101 vs. 135, respectively). Procedural complications and success in reducing MR were also higher in the COAPT trial. These are truly landmark findings and will likely have a significant impact on the management of patients with secondary MR.

References

1. 1. Three-year outcomes: Presented by Dr. Michael J. Mack at the Transcatheter Cardiovascular Therapeutics meeting (TCT 2019), San Francisco, CA, September 28, 2019.
2. 2. Asch FM, Grayburn PA, Siegel RJ, et al., on behalf of the COAPT Investigators. Transcatheter Mitral Valve Replacement in Patients With Heart Failure and Secondary Mitral Regurgitation: From COAPT Trial. J Am Coll Cardiol 2019;Sep 28:[Epub ahead of print].
3. 3. Arnold SV, Chinnakondepalli KM, Spertus JA, et al., on behalf of the COAPT Investigators. Health Status After Transcatheter Mitral-Valve Repair in Heart Failure and Secondary Mitral Regurgitation: COAPT Trial. J Am Coll Cardiol 2019;73:2123-32.
4. 4. Editorial Comment: Iung B, Messika-Zeitoun D. Transcatheter Mitral Valve Repair in Secondary MR: New Findings and New Challenges. J Am Coll Cardiol 2019;73:2133-4.
5. 5. COAPT: Presented by Dr. Federico M. Asch at the American College of Cardiology Annual Scientific Session (ACC 2019), New Orleans, LA, March 17, 2019.
6. 6. COAPT QoL Subanalysis: Presented by Dr. Suzanne Arnold at the American College of Cardiology Annual Scientific Session (ACC 2019), New Orleans, LA, March 17, 2019.
7. 7. Stone GW, Lindenfeld JA, Abraham WT, et al., on behalf of the COAPT Investigators. Transcatheter Mitral-Valve Repair in Patients With Heart Failure. N Engl J Med 2018;379:2307-18.
8. 8. Editorial: Nishimura RA, Bonow RO. Percutaneous Repair of Secondary Mitral Regurgitation — A Tale of Two Trials. N Engl J Med 2018;379:2374-6.
9. 9. Presented by Dr. Gregg W. Stone at the Transcatheter Cardiovascular Therapeutics meeting (TCT 2018), San Diego, CA, September 23, 2018.