126 - Predictors of Normal LV Size in Chronic Severe Mitral Regurgitation: Implications for Treatment

Abstract

Introduction: Guidelines suggest that patients with chronic severe mitral regurgitation (CSMR) inevitably have LV dilation. The corollary of this is that those with normal LV size are unlikely to have CSMR. We have observed a group of patients whose LV size remains normal despite CSMR. Hypothesis: 1. Patients with CSMR can have a normal LV size. 2. Patients with normal LV size and CSMR have similar rates of heart failure (HF) related morbidity as those with a dilated LV. Methods: Patients ≥18 years old undergoing TTE for severe MR from 2007–2015 were studied retrospectively. Those with EF < 60%, ≥moderate aortic valve regurgitation, mixed mitral stenosis/MR, prior mitral valve surgery, acute or secondary MR, hypertrophic cardiomyopathy were excluded. Results: Out of 360 patients 99 had a dilated LV [27.5% (95% CI 23%-32.4%)]. Both groups (dilated vs non-dilated LV) had severe MR by quantification. The chronicity of MR is indicated by severe LA enlargement in both groups [57.2 ± 28.9 ml/m2 vs 48.2 ± 22.1 ml/m2, p 0.006]. They had similar rates of atrial fibrillation (a fib) [33% vs 30%, p 0.61] and pulmonary hypertension (pHTN) [41.8 ± 13.6 mmHg vs 42.8 ± 16.5 mmHg, p 0.6] . Univariate analysis showed older patients, [68 ± 16 vs 63 ± 15 years, P < .05], those with HTN [55% vs 77%, P < .01] and LV hypertrophy (LVH) [33% vs 68%, P < .01] to be more likely to have normal LV size. Multivariable analysis revealed LVH [OR 0.28, P < .001] and HTN [OR 0.51, P < .05] as independent predictors of normal LV size in presence of CSMR. There was no difference in BNP levels [514 vs 558 pg/ml, p 0.6], time to first HF hospitalization or death (Fig. 1 and 2), or rate of HF hospitalizations [0.45 vs 0.35 per patient-year, p 0.47] between groups. Time from diagnosis of severe MR to surgery [51 vs 67.5 days, p 0.12] and rate of surgical intervention [73 vs 62%, p 0.62] was also similar. Importantly, post-operative EF was significantly lower in the dilated LV group [52 vs 56%, p 0.008]. Conclusion: 1. Chronic severe MR can exist with normal LV size. 2. Patients with HTN and/or LVH may not dilate their LV. 3. Rates of hospitalization, death, a fib, pHTN appear to be similar in patients with CSMR despite presence or absence of LV dilation. 4. LV size may not be as reliable in patients with HTN and LVH in deciding when to refer for MV surgery. Other clinical sequelae may be of more importance in this cohort.View Large Image Figure ViewerDownload Hi-res image Download (PPT)