Myocardial perfusion improvement and mechanism after percutaneous intramyocardial septal radiofrequency ablation in obstructive hypertrophic cardiomyopathy: a study of myocardial contrast echocardiography

The data on myocardial perfusion of the percutaneous intramyocardial septal radiofrequency ablation (PIMSRA) for obstructive hypertrophic cardiomyopathy (HOCM) are still lacking, although PIMSRA have been proved to be of great safety and efficacy. The aim of this study was to quantitatively analyze the changes in myocardial perfusion after PIMSRA using myocardial contrast echocardiography (MCE). 27 HOCM patients treated with PIMSRA were retrospectively analyzed, and their echocardiographic parameters and perfusion parameters of MCE were collected before and 12 months after PIMSRA. A reperfusion curve was used to quantify microvascular blood volume (A), microvascular flux rate (β), and microvascular blood flow (MBF) of each segment. Then the value difference (Δ) of parameters between post- and pre-operation were calculated. Finally, the correlation between the changes in MBF and in each echocardiographic parameter was analyzed. (1) Compared with baseline, the global A, β and MBF were significantly increased in HOCM patients after PIMSRA (all P < 0.001). The β, MBF were increased in the interventricular septum (P < 0.001, respectively), and the A, β, MBF were increased in the left ventricular wall (all P < 0.001). (2) Correlation analysis showed that the ΔMBF of interventricular septum was mainly negatively correlated with the maximum interventricular septum thickness (ΔIVSTmax, r=-0.670, P < 0.001), mean interventricular septum thickness (ΔIVSTmean, r=-0.690, P < 0.001), and left ventricular mass index (ΔLVMI, r=-0.774, P < 0.001), while the ΔMBF of left ventricular wall was positively correlated with left ventricular end-diastolic volume index (ΔLVEDVI, r = 0.621, P = 0.001) and stroke volume index (ΔSVI, r = 0.810, P < 0.001). Myocardial perfusion was improved at both interventricular septum and ventricular wall in HOCM patients after PIMSRA. MCE can provide a new dimension for the efficacy evaluation to PIMSRA procedure.