Left Ventricular Assist Device Implantation in Patients with Preoperative Severe Mitral Regurgitation

Abstract

We examined cardiac features associated with residual mitral regurgitation (MR) following continuous-flow left ventricular assist device (cfLVAD) implant. From 2003 to 2017, 134 patients with severe MR underwent cfVLAD implant without mitral valve (MV) intervention. Echocardiographic (echo) assessment occurred pre-cfLVAD, early post-cfLVAD, and at last available echo. Ventricular and atrial volumes were calculated from established formulas and normalized to be predicted. Cluster analysis based on preoperative normalized left ventricular and atrial volumes, and MV height identified grades 1, 2, and 3 with progressively larger cardiac chamber sizes. Median early echo follow-up was 0.92 (0.55, 1.45) months and the last follow-up was 15.12 (5.28, 38.28) months. Mitral regurgitation improved early after cfLVAD by 2.10 ± 1.16 grades (p < 0.01). Mitral regurgitation severity at the last echocardiogram positively correlated with the preoperative left ventricular volume (p = 0.014, R = 0.212), left atrial volume (p = 0.007, R = 0.233), MV anteroposterior height (p = 0.032, R = 0.185), and MV mediolateral diameter (p = 0.043, R = 0.175). Morphologically, smaller grade 1 hearts were correlated with MR resolution at the late followup (p = 0.023). Late right ventricular failure (RVF) at the last clinical follow-up was less in grade 1 (4/48 [8.3%]) compared with grades 2 and 3 (26/86 [30.2%]), p = 0.004). Grade 1 cardiac dimensions correlates with improvement in severe MR and had less late RVF.

Role of the mitral valve in left ventricular assist device pathophysiology

“…Building upon findings by previous groups on predictor of residual SMR, we employed a non-hypothesis driven statistical phenotyping of cardiac chamber dimensions. This revealed the correlations between pre-cfLVAD chamber size to MV tenting, early and late post-cfLVAD MR resolution and the occurrence of RV failure ( 30 ). Interestingly, LV and left atrial (LA) sizes greater than 3 times the normalized dimensions had twice the risk of having residual SMR at last follow up compared to those less than 3 times the normal size (50–55% vs. 25% respectively).…”

“…These patients were two times more likely to have severe RV dysfunction and over three times the rate of manifesting the clinical symptoms of late RV failure. Late RV failure also highly correlated with lower survival ( P = 0.006) ( 30 ). Kassis et al reported similar findings where postoperative LVEDD and RV dimensions was larger in patients with significant residual MR and this was associated with worse RV function by quantitative parameters ( 20 ).…”

“…Kassis et al reported similar findings where postoperative LVEDD and RV dimensions was larger in patients with significant residual MR and this was associated with worse RV function by quantitative parameters ( 20 ). This is likely a result of consistently elevated afterload demands on the RV resulting from increased pulmonary vascular resistance which contributes to RV failure over a prolonged period ( 30 ). Kapelios et al also reported the entity of late-onset RVF during LVAD support where RVF can occur many months to years from device implantation.…”

“…Larger LA are more likely to have elevated atrial pressures, mitral annular dilatation, LA fibrosis, impaired atrial systole/diastolic function ( 8 ). Indeed, very large hearts ( Figure 2 ; 30 ) had the greatest LA volumes despite LVAD decompression of the ventricle and also had the largest incidence of residual SMR (55.6%) ( 30 ).…”

“…It is important to note while LVAD decompression greatly reduced cardiac volume, mitral annular dimensions, and leaflet tenting, this may did not correlate with leaflet coaptation nor MR resolution in patients with very large hearts ( 30 ). This is congruent with Kitada et al’s findings where preoperative posterior displacement of the mitral leaflet coaptation point was a predictor for significant residual MR at 1 week following LVAD implant ( 1 ).…”