Abstract 4619: Time to Significant Gradient Reduction Following Septal Balloon Occlusion Predicts the Magnitude of Final Gradient Response During Septal Ethanol Ablation in Patients With Hypertrophic Obstructive Cardiomyopathy
Background: Septal ethanol ablation (SEA) is an alternative therapy to myectomy surgery in patients with hypertrophic obstructive cardiomyopathy (HOCM). We have noted during this procedure that patients have a variable gradient response to occlusion of the septal perforator artery prior to ethanol infusion for SEA. The purpose of this study was to investigate whether a relationship exists between an acute reduction in resting LVOT gradient with balloon occlusion and the final invasive gradient response following ethanol ablation.
Methods: 120 patients (mean age 60 [range 16 to 87 years], 50% female) with HOCM underwent SEA at our institution. The peak resting gradient across the LVOT was calculated by measuring the difference in maximum pressure recorded in the left ventricle (LV) using a pigtail catheter compared with central aortic pressure using an angioplasty guiding catheter. The time to significant pressure gradient drop was recorded; a significant drop in resting gradient was defined as >50% decrease from baseline resting gradient following occlusion of the septal perforator coronary artery supplying the basal septum, or the maximum gradient decrease by 11 min.
Results: Mean basal septal thickness was 20±4mm. Overall procedural success occurred in 109 patients (90%). Data on time to significant gradient reduction was available for 80 patients (89%). Time required for balloon inflation to significantly reduce the LVOT gradient ranged from 25 sec to 11 min (mean 3.6±2 min). The mean maximum resting gradient of 86±43mmHg decreased to 17±11mmHg following ethanol ablation (−80.2 %.). Time to significant decrease in resting gradient with balloon occlusion was highly correlated with the overall magnitude of final gradient reduction following SEA (correlation coefficient (r) =−0.86, p<0.0001)
Conclusion: This is the first study to demonstrate a correlation between septal perforator balloon occlusion and the magnitude of final gradient response during SEA. Our findings suggest that patients who have a rapid gradient reduction during balloon occlusion are more likely to have a larger final gradient response with ethanol ablation. Whether this finding is correlative with long-term gradient responses in these patients warrants further investigation.