Introduction and methods

Mitral Regurgitation After MitraClip Implantation in Patients with Heart Failure and Secondary Mitral Regurgitation: Echocardiographic Outcomes from the COAPT Trial

Presented at ACC.19 by Federico M. Asch (Georgetown University, Washington, DC, USA)

Secondary or functional mitral regurgitation (SMR) is present in the majority of heart failure (HF) patients and is severe in 10-15% of HF patients. The COAPT trial demonstrated that implantation of the MitraClip in HF patients with moderate-to-severe (3+) or severe (4+) SMR (n=614) reduced rate of hospitalizations and improved survival,, functional class of HF and severity of MR vs guideline-directed medical therapy (GDMT). Evaluation of SMR severity by echocardiography in HF patients is complex and challenging and there is disagreement on how to define the severity, which is reflected by conflicting European and American guidelines.

Therefore, in this COAPT Echo substudy, echocardiographic MR grading criteria used in the COAPT trial were described. Moreover, baseline echocardiographic characteristics that predict clinical outcomes (responders and non-responders to MitraClip) were investigated. Several MR variables (effective regurgitant orifice area [EROA], pulmonary vein [PV] flow, regurgitant volume [RV], regurgitant fraction [RF}, vena contracta [VC], proximal isovelocity surface area [PISA} and others) were studied. Long-term outcomes were mortality and hospitalization for HF (HHF) at 24 months.

Main results

• 3+ or 4+ SMR was defined by presence of 1 of 3 criteria (tier 1: EROA ≥0.3 cm² or PV systolic flow reversal, tier 2: EROA 0.2 -<0.3 cm² plus one additional characteristic [RV ≥45 ml/beat, RF ≥40%, VC width >0.5], tier 3: EROA not measured or <0.2 cm² with at least 2 characteristics [as for tier 2 plus PISA radius >0.9 cm, large holosystolic jet wrapping around left atrium (LA), peak E velocity ≥150 cm/s]).
• Hazard ratio’s for 24-monts all-cause mortality or first HHF favored Mitraclip + GDMT vs GDMT alone in all tested subgroups based on baseline left ventricular ejection fraction (LVEF) (except in those with EF > 40%), left ventricular end diastolic volume (LVEDV), left ventricular end systolic volume (LVESV), LV stroke volume,, left ventricular end diastolic diameter (LVEDD). or echocardiographic variables.
• In patients who were treated with GDMT only, tricuspid (TR) grade, LVEF, right ventricular systolic pressure (RVSP) and EROA at baseline predicted all-cause mortality or first HHF at 24 months
• In those with MitraClip implantation, RSVP and STS Repair Score predicted poor outcomes.

Conclusion

In patients with HF and 3+ or 4+ SMR, MitraClip provided substantial death and HHF benefits in all echocardiographic subgroups, regardless of degree of LV dysfunction, LV dimensions, pulmonary hypertension, severity of TR or individual MR parameters (all responders).

Baseline LVEF, TR grade, RVSP and EROA predicted poor outcomes in patients with HF treated with GDMT alone. Dr. Asch summarized it as ‘in the control group, the predictors are the usual suspects’. In those who received MitraClip treatment, RVSP and STS Repair Score were the only 2 independent predictors of poor outcomes. These baseline criteria can be used to select patients who may or may not respond well to MitraClip.

Discussion

The discussant Joseph Cleveland congratulated the researchers on starting to look at other things than what we usually look at, in this patient group that is dying of HF. Something is going on in the right heart, so more work should be done on right heart pressure.

In the same session, the results of another substudy of the COAPT trial were presented by Suzanne V Arnold ((Saint Luke‘s Mid America Heart Institute/UMKC Kansas City, Missouri, USA). She presented health status outcome data using KCCQ (Kansas City Cardiomyopathy Questionnaire) score and showed that KCCQ score was higher in MitraClip patients vs GDMT patients (KCCQ score difference at 24 months: 12.8, P<0.001).

In response to the quality of life (QoL) data, discussant Janet Wyman emphasized that these patients live uncomfortable lives. We should therefore not only address how well we fix their physical problems, but also how does the patient feel? Can they do the things they want to do? This was a conscious effort to look at how we are impacting their lives for a longer period of time: is the change we are making a durable change in their lives?

- Our coverage of ACC.19 is based on the information provided during the congress –