Trends in Ischemic Mitral Regurgitation Following ST-Elevation Myocardial Infarction Over a 20-Year Period

Background: Ischemic mitral regurgitation (IMR) is a common complication of acute ST-elevation myocardial infarction (STEMI). Little is known regarding the impact of IMR over a long period of follow up.Methods: Of 3,208 consecutive STEMI patients from a prospective registry, full echocardiographic information was available for 2,985 patients between the years 2000 and 2020. We compared the two decades- 2001 to 2010 and 2011 to 2020, and assessed for the presence of IMR at baseline, 3 (range 2–6) months and 12 (range 10–14) months after the index event.Results: One thousand six hundred and sixty six patients were included in the first decade, 1,319 in the second. Mean patient age was 61.3 ± 12.3 years, 21.1% female patients in the first decade vs. 60.9 ± 12.0 years and 22.2% female in the second (p = 0.40 and p = 0.212, respectively). Rates of moderate IMR or above during the index admission were 17.2% in the first period and 9.3% in the second one (p < 0.001). After 3 months, the rate of IMR was 48.5% for those who suffered from IMR at baseline, vs. 9.5% for those without IMR at baseline (HR- 4.2, p < 0.001). Death rates for those with moderate IMR or above were 14.7% and 17.8% after 1 and 2 years, respectively, vs. 7.3 and 9.6% for those without (p < 0.001 for both). IMR was associated with 1 year mortality in multivariate analysis (HR-1.37; 1.09–2.20, p = 0.009), as well as in propensity score matched analysis (HR 1.29; CI: 1.07–1.91; p < 0.001).Conclusions: IMR is a common complication following acute STEMI, impacting prognosis. Rates of IMR have declined significantly over the years.

Mitral Plasticity: The Way to Prevent the Burden of Ischemic Mitral Regurgitation?

The ischemic impairment of the left ventricular contractility, followed by an adverse remodeling leading to the displacement of the papillary muscles (PMs), increased tethering forces and loss of valve competence has been the long-term accepted definition of ischemic mitral regurgitation (IMR). Over the years, different approaches of management have attempted to address valve regurgitation, nevertheless failing to achieve satisfactory outcomes. Recent studies have observed some structural and molecular changes of the mitral valve (MV), challenging the concept of a bystander passive to the subvalvular involvement. Indeed, the solely mechanical stretch of the PMs, as in the dilated left ventricle because of the aortic valve regurgitation, is not enough in causing relevant MV regurgitation. This setting triggers a series of structural changes called “mitral plasticity,” leaflets increase in their size among others, ensuring an adequate systolic area closure. In contrast, the ischemic injury not only triggers the mechanical stretch on the subvalvular apparatus but is also a powerful promotor of profibrotic processes, with an upregulation of the transforming growth factor (TGF)-β signaling pathway, leading to a MV with exuberant leaflet thickness and impaired mobility. In this article, we revise the concept of IMR, particularly focusing on the new evidence that supports dynamic changes in the MV apparatus, discussing the consequent clinical insights of “mitral plasticity” and the potential therapeutic implications.

Left atrial geometry in an ovine ischemic mitral regurgitation model: implications for transcatheter mitral valve replacement devices with a left atrial anchoring mechanism

Background Transcatheter mitral valve replacement (TMVR) is a challenging, but promising minimally invasive treatment option for patients with mitral valve disease. Depending on the anchoring mechanism, complications such as mitral leaflet or chordal disruption, aortic valve disruption or left ventricular outflow tract obstruction may occur. Supra-annular devices only anchor at the left atrial (LA) level with a low risk of these complications. For development of transcatheter valves based on LA anchoring, animal feasibility studies are required. In this study we sought to describe LA systolic and diastolic geometry in an ovine ischemic mitral regurgitation (IMR) model using magnetic resonance imaging (MRI) and echocardiography in order to facilitate future research focusing on TMVR device development for (I)MR with LA anchoring mechanisms. Methods A group of 10 adult male Dorsett sheep underwent a left lateral thoracotomy. Posterolateral myocardial infarction was created by ligation of the left circumflex coronary artery, the obtuse marginal and diagonal branches. MRI and echocardiography were performed at baseline and 8 weeks after myocardial infarction (MI). Results Six animals survived to 8 weeks follow-up. All animals had grade 2 + or higher IMR 8 weeks post-MI. All LA geometric parameters did not change significantly 8 weeks post-MI compared to baseline. Diastolic and systolic interpapillary muscle distance increased significantly 8 weeks post-MI. Conclusions Systolic and diastolic LA geometry do not change significantly in the presence of grade 2 + or higher IMR 8 weeks post-MI. These findings help facilitate future tailored TMVR device development with LA anchoring mechanisms.

Tricuspid regurgitation in ischemic mitral regurgitation patients – prevalence, predictors for outcome and long-term follow-up

Background Functional tricuspid regurgitation (FTR) is common in left-sided heart pathology involving the mitral valve. The incidence, clinical impact, risk factors, and natural history of FTR in the setting of ischemic mitral regurgitation (IMR) are less known. Method We conducted a cohort study based on data collected from January 2012 to December 2014. Patients diagnosed with IMR were eligible for the study. The median follow-up was five years. The primary outcome is defined as FTR developing at any stage. Results Among the 134 IMR patients eligible for the study, FTR was detected in 29.9% (N=40, 20.0% mild, 62.5% moderate, and 17.5% severe). In the FTR group, the average age was 60.7±9.2 years (25% females), the mean LV ejection fraction (LVEF) was 37.3±6.45 [%], LA area 46.4±8.06 [mm2], LV internal diastolic diameter (LVIDD) 59.6±3.94 [mm], RV fractional area change (RVFAC) 22.3±4.36 [%], systolic pulmonary artery pressure (SPAP) 48.4±9.45 [mmHg]. Independent variables associated with FTR development were age ≥65y [OR 1.2], failed revascularization, LA area ≥42.5 [mm2] [OR 17.1], LVEF ≤24% [OR 32.5], MR of moderate and severe grade [OR 419.4], moderate RV dysfunction [OR 91.6] and pulmonary artery pressure of a moderate or severe grade [OR 33.6]. During follow-up, FTR progressed in 39 (97.5%) patients. Covariates independently associated with FTR progression were lower LVEF, RV dysfunction, and PHT of moderate severity. LA area and LVIDD were at the margin of statistical significance (p=0.06 and p=0.05, respectively). Conclusion In our cohort study, FTR development and progression due to IMR was a common finding. Elderly patients with ischemic MR following unsuccessful PCI are at higher risk. FTR development and severity are directly proportional to LV ejection fraction, to the extent of mitral regurgitation, and SPAP. FTR tends to deteriorate in the majority of patients over a mean of 5-y follow-up. FUNDunding Acknowledgement Type of funding sources: None.