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Secondary Mitral Regurgitation Volume to LVEDV Ratio
Quick Takes
- In a single-center, nonrandomized, retrospective study, there was a nonsignificant trend toward lower survival among medically treated patients with secondary mitral regurgitation RVol/LV end-diastolic volume ratio ≥20% vs. <20%.
- In the same cohort after mitral intervention, the higher RVol/EDV ratio was associated with reduced all-cause mortality.
Study Questions:
Among patients with secondary mitral regurgitation (SMR), is there a relationship between the ratio of mitral regurgitant volume (RVol) to left ventricular end-diastolic volume (LVEDV) and prognosis?
Methods:
In a single-center, nonrandomized, retrospective study, 379 patients (mean age 67 ± 11 years, 63% male) with heart failure and at least moderate-to-severe SMR on echocardiography were identified and divided into two groups according to the RVol (measured using the proximal isovelocity surface area [PISA] method)/EDV ratio: RVol/EDV ≥20% (greater MR/smaller EDV) and <20% (smaller MR/larger EDV). The primary endpoint of all-cause mortality was obtained from the electronic record, which is linked to a governmental death registry database.
Results:
Patients with RVol/EDV ratio ≥20% had less severe heart failure symptoms and were less frequently treated with a diuretic compared to patients with RVol/EDV ratio <20%. Patients with a RVol/EDV ratio <20% more often underwent cardiac resynchronization therapy (CRT) (66% vs. 27%), whereas those with a RVol/EDV ratio ≥20% more often underwent mitral valve intervention (81% vs. 51%); of 234 mitral valve interventions, 158 (68%) were surgical mitral valve replacement or repair and 76 (32%) were a transcatheter edge-to-edge repair with MitraClip. During a median (interquartile range) follow-up of 50 (26-94) months, 199 (52.5%) patients died. Considering patients only receiving medical therapy, there was a nonsignificant trend that mortality tended to be higher among patients with RVol/EDV ratio ≥20% compared to RVol/EDV ratio <20% (5-year estimated rates 24.1% vs. 18.4%, respectively; p = 0.08). Conversely, considering the entire follow-up period including mitral valve interventions, patients with RVol/EDV ratio ≥20% had lower rates of all-cause mortality compared to patients with RVol/EDV ratio <20% (5-year estimated rates 39.0% vs. 44.8%, respectively; p = 0.02). On multivariable analysis, higher RVol/EDV ratio was independently associated with lower all-cause mortality (hazard ratio per 5% increment, 0.93; p = 0.02).
Conclusions:
Among patients with significant SMR treated medically, there was a nonsignificant trend such that survival tended to be lower among patients with a higher RVol/EDV ratio. Conversely, when follow-up after mitral valve intervention was included, a higher RVol/EDV ratio was independently associated with reduced all-cause mortality.
Perspective:
In this single-center study of patients with heart failure and at least moderate-to-severe SMR, there was a nonsignificant trend toward lower survival among medically treated patients when the RVol/EDV ratio was ≥20% compared to <20%, but conversely a lower all-cause mortality associated with the higher RVol/EDV ratio after surgical or transcatheter mitral intervention.
Discordant results from the COAPT and MITRA-FR trials raised the concept of proportionate vs. disproportionate SMR, using the ratio of SMR effective regurgitant orifice area (EROA) indexed to LVEDV. Based on that theory, patients with a higher EROA/EDV ratio (SMR disproportionate to LV enlargement) are more likely to benefit from CRT or mitral intervention. But it is not clear how the findings from this study fit. It might be that RVol/EDV ratio is similar to EROA/EDV, with a higher ratio potentially identifying patients more likely to benefit from either CRT or transcatheter mitral intervention. But in this nonrandomized study, the two groups underwent different interventions at different rates, with one group undergoing more CRT and the other more surgical or transcatheter mitral interventions. In the context of the limitations inherent to a nonrandomized database review, difficulties in SMR quantification using PISA, inherent differences between patient groups and the respective therapies received, and the low rate of transcatheter mitral interventions (the only mitral intervention having been prospectively associated with improved outcomes in the setting of heart failure with reduced LV systolic function and SMR); it is not clear how to use the conclusions from this study other than to await something prospective and controlled.
Clinical Topics: Arrhythmias and Clinical EP, Cardiac Surgery, Geriatric Cardiology, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Valvular Heart Disease, Implantable Devices, Cardiac Surgery and Arrhythmias, Cardiac Surgery and Heart Failure, Cardiac Surgery and VHD, Acute Heart Failure, Interventions and Imaging, Interventions and Structural Heart Disease, Echocardiography/Ultrasound, Mitral Regurgitation
Keywords: Cardiac Resynchronization Therapy, Cardiac Surgical Procedures, Cardiology Interventions, Diagnostic Imaging, Diuretics, Echocardiography, Geriatrics, Heart Failure, Heart Valve Diseases, Hypertrophy, Left Ventricular, Mitral Valve Insufficiency, Prognosis, Stroke Volume
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