Time to significant gradient reduction following septal balloon occlusion predicts the magnitude of final gradient response during alcohol septal ablation in patients with hypertrophic obstructive cardiomyopathy.

OBJECTIVES

The purpose of this study was to investigate whether a relationship exists between an acute reduction in resting left ventricular outflow tract (LVOT) gradient with balloon occlusion and the final invasive gradient response following alcohol septal ablation (ASA).

BACKGROUND

ASA is an alternative therapy to myectomy surgery to reduce the basal septal thickness and decrease the resting and/or provocable LVOT gradient in patients with hypertrophic cardiomyopathy. Patients have a variable gradient response to occlusion of the septal perforator artery before ethanol infusion for ASA.

METHODS

From November 1998 to November 2008, 120 patients (mean age 60 years [range 16 to 87 years], 50% women) with hypertrophic cardiomyopathy underwent ASA at our institution. The resting LVOT gradient (peak systolic left ventricle [LV] pressure - peak systolic aortic pressure) was measured continuously during the ASA procedure. The time to significant LVOT gradient decrease (defined as >50% decrease from baseline) was recorded following balloon occlusion of the dominant septal perforator coronary artery, which was found to perfuse the basal septum based on contrast echocardiographic studies.

RESULTS

The mean baseline resting LVOT gradient was 86 ± 43 mm Hg, and it decreased to 17 ± 11 mm Hg following ASA (-80.2%). The mean time to significant gradient reduction was 3.6 ± 2 min (range 25 s to 11 min). The time to significant LVOT gradient reduction strongly correlated with the final magnitude of gradient reduction following ASA (r = -0.81, p < 0.001).

CONCLUSIONS

This study demonstrates a correlation between the time to significant LVOT gradient reduction following septal perforator balloon occlusion and the magnitude of final gradient response after ASA.