Feature tracking and mapping analysis of myocardial response to improved perfusion reserve in patients with refractory angina treated by coronary sinus Reducer implantation: a CMR study.

Coronary sinus (CS) Reducer implantation improves myocardial perfusion and symptoms in patients with debilitating refractory angina. Its impact on myocardial remodeling remain uncertain. Aim of the present study was to assess possible impact of CS Reducer on myocardial systolic-diastolic deformation and microstructural remodeling, as assessed through cardiac magnetic resonance (CMR) feature tracking and mapping analysis. Twenty-eight consecutive patients with refractory angina underwent multiparametric stress CMR before and 4 months after CS Reducer implantation. Eight patients were excluded (6 for absence of inducible ischemia, 2 for artifacts). Modifications in 3D systo-diastolic myocardial deformation were evaluated using feature tracking analysis on rest cine images. Myocardial microstructural remodeling was assessed by native T1 mapping, cellular and matrix volume and extracellular volume fraction (ECV). Collaterally, the percentage of ischemic myocardium (ischemic burden %) and the myocardial perfusion reserve index (MPRI) were measured. After CS Reducer implantation, myocardial contractility improved (ejection fraction rose from 61 to 67%; p = 0.0079), along with longitudinal (from - 16 to - 19%; p = 0.0192) and circumferential strain (from - 18 to - 21%; p = 0.0017). Peak diastolic radial, circumferential and longitudinal strain rate did not change (p > 0.05), and no changes in native T1, ECV, cellular and matrix volume were observed. Myocardial perfusion improved, with a reduction of ischemic burden (13-11%; p = 0.0135), and recovery of intramural perfusion balance in segments with baseline ischemia (MPRi endocardial/epicardial ratio from 0.67 to 0.96; p = 0.0107). CS Reducer improves myocardial longitudinal and circumferential strain, without microstructural remodeling and no impact on diastolic proprieties.