Risk stratification on echocardiography and outcome in ischaemic mitral regurgitation

Abstract

Abstract Background Ischaemic mitral regurgitation (IMR) confers a poor prognosis. Transcatheter intervention may improve survival but benefit is likely to depend on severity of IMR relative to LV remodelling following myocardial infarction (MI). In theory, those with “discordant” IMR (significant regurgitant volume without severe LV dilatation or impairment), are expected to benefit most from mitral intervention. While subcategorization may help to inform treatment, there are no data on post-MI patients in this respect. Purpose To determine the incidence of discordant & concordant IMR categorised on echocardiography post-MI and impact on outcomes. Methods 1000 consecutive patients admitted to our hospital with myocardial infarction who underwent coronary angioplasty were included. Early inpatient TTE was performed by accredited echocardiographers using standard multiparametric quantification. Using TTE parameters, 4 subgroups were identified (figure) according to the degree of MR relative to LV remodelling. Thresholds were based on European guidelines (± 2SD from normal) and median value among survivors for vena contracta (VC): – LVEF: 52% (♂), 54% (♀) – Indexed LV end diastolic volume (LVEDVi): 74ml/m2 (♂), 61ml/m2 (♀) – Effective regurgitant orifice area (EROA) ≥0.2cm2 – Regurgitant volume (RVol) ≥30ml – VC ≥0.5cm Results MR was seen in 294/1000 patients (29.4%) with a severity of mild (76%), moderate (21%) and severe (3%). Concordant and discordant IMR were each seen in 16/294 (5%) of IMR patients post-MI. After a mean follow up of 3.2 years, IMR patients had a 3% rate of heart failure (HF) within 1 year and 19% mortality. Non-survivors had significantly worse IMR (PISA 0.65±0.25cm vs 0.54±0.19cm; p=0.033; VC 0.63±0.25cm vs 0.49±0.18cm; p=0.014), worse LV function (LVEF 44±17% vs 51±13%; p<0.001), larger LV (LVEDVi 67±23ml/m2 vs 60±22ml/m2; p=0.032) and larger indexed LA volume (LAVi) (44±22ml vs 35±15ml; p<0.001). Those with concordant IMR had the worst survival (50%) although almost 1 in 5 of those with discordant MR died within the follow up period (19%). Using multivariable Cox regression, significant predictors of mortality included LVEF (p<0.001; HR 0.96, 0.94–0.98) and LAVi (p<0.001; HR 1.02, 1.01–1.03) but not LVEDVi. Conclusion 1) Significant predictors of mortality in IMR include LA dilatation and decline in LVEF, but not LV dilatation. 2) Although discordant severe IMR is uncommon following MI, mortality if left untreated remains high. Attention should be paid to early selection of this cohort for intervention. Funding Acknowledgement Type of funding source: None