Abstract 15351: Changes in Left Ventricular End-diastolic Pressure Following Alcohol Septal Ablation in Hypertrophic Obstructive Cardiomyopathy

Abstract

Background: LVEDP is a representation of left ventricular diastolic function. An increased LVEDP correlates to decreased compliance and increased left ventricular workload, which can be seen in HOCM. In HOCM, the interventricular septum is hypertrophied creating a LVOT obstruction and elevated LVEDP. ASA induces a targeted septal infarction to reduce the size of the septum and relieve the LVOT obstruction. Non-targeted infarction in a MI can increase LVEDP. Our study aims to determine the immediate effect of ASA on LVEDP in HOCM patients. It is hypothesized that ASA immediately reduces LVEDP. Methods: Retrospective study of 113 patients where pre and post-ablation LVEDP were compared. LVEDP was measured at the end-expiratory R wave of the ECG tracing during the procedure. LVEDP measurements were recorded at the post-“a” wave points at the immediate start of the procedure (Group A), prior to the alcohol injection under mild sedation (Group B), and at the conclusion of the successful ablation (Group C). Results: Groups A, B, and C were compared using two-tailed t-tests. We found no statistical difference between groups A and B (mean A=31.34 vs. mean B=31.54; p=0.695). LVEDP was significantly lower in group C when compared to group A (mean A=31.34 vs. mean C=25.82; p=6.525E-9). LVEDP was also significantly lower in group C when compared to group B (mean B=31.54 vs. mean C=25.82; p=4.047E-9). A linear regression model showed no significant correlation between LVEDP and LVOT gradient reduction following ASA (R 2 =0.0258, Significance F=0.0891). Conclusion: This data supports our hypothesis that ASA immediately reduces LVEDP despite inducing an infarct of the septal myometrium. There is no effect of sedation on LVEDP during the procedure. Since LVEDP reduction does not seem to correlate with LVOT gradient reduction, the reduction in LVEDP is likely related to other hemodynamics improvements including reduction in mitral regurgitation and immediate improvement in diastolic function. Future studies can include evaluating a correlation between LVEDP reduction and immediate hemodynamic changes. They could also evaluate a correlation between the immediate drop in LVEDP and long-term outcomes to predict the prognosis of HOCM patients based on their ASA outcomes.