Degenerative Mitral Regurgitation Outcomes in Asian Compared With European-American Institutions

Abstract

Background: Clinical outcome and interventional thresholds for degenerative mitral regurgitation (DMR) were developed in studies of patients at European and American institutions (EAIs), but little is known about patients at Asian institutions (AsIs).

Objectives: This study sought to contrast DMR presentation/management/outcomes of AsI patients vs EAI patients.

Methods: Patients with DMR due to flail leaflet from Hong Kong and Singapore (AsI cohort, n = 737) were compared with EAI patients (n = 682) enrolled in the MIDA (Mitral regurgitation International Database) registry with similar eligibility criteria.

Results: AsI patients presented similar DMR lesion/consequences vs EAI patients, but they were younger, with fewer symptoms (74% vs 44% Class I), more sinus rhythm (83% vs 69%), and lower EuroSCORE II (European System for Cardiac Operative Risk Evaluation II) (0.9 ± 0.5 vs 1.4 ± 1.5; all P < 0.0001). Imaging showed smaller absolute left atrial/ventricular dimensions in AsI patients, belying cardiac dilatation with larger body surface area-indexed diameters (all P < 0.01). Surgical/interventional mitral repair was similarly predominant (90% vs 91%; P = 0.47), and early repair was similarly beneficial (for AsI patients, adjusted HR: 0.28; 95% CI: 0.16-0.49; for EAI patients, HR: 0.32; 95% CI: 0.20-0.49; both P < 0.0001). However, AsI patients underwent fewer interventions (55% ± 2% vs 77% ± 2% at 1 year; P < 0.0001) and incurred excess mortality (adjusted HR: 1.60 [95% CI: 1.13-2.27] vs EAI patients; P = 0.008) at long-term postdiagnosis. Propensity score matching (434 patient pairs), which balanced all clinical characteristics, confirmed that there was undertreatment and excess mortality in the long term in AsI patients with DMR (P < 0.0001).

Conclusions: Imaging may underestimate volume overload in AsI patients due to smaller cardiac cavities related to smaller body size compared with EAI patients with similar mitral lesions and DMR severity. AsI patients enjoy similar mitral repair predominance and early intervention benefits but undergo fewer mitral interventions than EAI patients and incur subsequent excess mortality, suggesting the need to account for imaging and cultural specificity to improve DMR outcomes worldwide.

Keywords: degenerative mitral regurgitation; ethnicity; mitral surgery; outcome.

Graphical abstract

Central Illustration

DMR in AsIs vs EAIs Imaging diagnosis of degenerative mitral regurgitation (DMR) due to flail mitral leaflet (top left) is similar with similar flail location and DMR severity, but striking differences at presentation mostly relate to smaller body size in Asian institutions (AsIs) (red) vs European and American institutions (EAIs) (blue) centers (top right, 2 bar graphs) that may lead to underestimation of volume overload. The impact of early mitral intervention on survival (lower row, right) is similar, but rates of mitral interventions in Asians (lower row, middle) are markedly lower. The long-term outcome shows age-adjusted excess mortality in Asians (lower row, left). LA = left atrial; LVEDD = left ventricular end-diastolic dimension; LVEF = left ventricular ejection fraction; MR = mitral regurgitation; RVSP = right ventricular systolic pressure.

Figure 1

Cumulative Incidence of Mitral Valve Intervention Rates of mitral intervention after diagnosis indicated over the first 5 years of follow-up (left) and expanded during the first year postdiagnosis (right). Note that among Asians there were fewer mitral interventions, particularly in the first year postdiagnosis, with the later interventional rate flatter than in Westerners. AsI = Asian institutions; EAI = European and American institutions.

Figure 2

Postoperative Survival After Mitral Valve Intervention Survival rates after mitral interventions are similar in Asians and Westerners and remain so even after comprehensive adjustment. Abbreviations as in Figure 1.

Figure 3

Effect of Early Surgery and Long-Term Survival in Landmark Analysis Survival beyond the first 3 months postdiagnosis according the treatment indicated during the first 3 months. The gray shaded area marks the landmark time set at 3 months from diagnosis. Note the markedly superior survival after early surgery that persists even after comprehensive adjustment.

Figure 4

Survival by Early Surgery Stratified by Origin in Landmark Analysis Survival beyond the first 3 months postdiagnosis is presented comparing those receiving early surgery with those followed conservatively during the first 3 months postdiagnosis in Western (left) and Asian (right) institutions. The gray shaded area marks the landmark time set at 3 months from diagnosis. Note that the survival benefit associated with early surgery is similar in both cohorts. The dark red line indicates conservative. Abbreviations as in Figure 1.

Figure 5

Age-Adjusted Survival After DMR Diagnosis in AsI Patients and EAI Patients The age-adjusted survival after degenerative mitral regurgitation (DMR) diagnosis is similar during the first 5 years of follow-up, but secondarily, high-mortality rates observed in As-I patients yields overall excess mortality in this cohort confirmed in multivariable analysis. Abbreviations as in Figure 1.