Extent of Myocardial Infarction and Reverse Remodeling Assessed by Cardiac Magnetic Resonance in Patients With and Without Right Bundle Branch Block Following Alcohol Septal Ablation for Obstructive Hypertrophic Cardiomyopathy

Percutaneous alcohol septal ablation (ASA) is an established technique for the relief of refractory symptoms in patients with obstructive hypertrophic cardiomyopathy. Most subjects develop right bundle branch block (RBBB) after ASA, but it is not known whether these patients have similar infarct characteristics, which may influence left ventricular (LV) pressure gradient reduction and reverse remodeling, compared with those without RBBB. Twenty-seven consecutive patients (15 men, 12 women; mean age 62 ± 16 years) were studied with electrocardiography and cardiac magnetic resonance imaging at baseline and 1 and 6 months (n = 25) after ASA. Infarct size and location were determined at 1 month by delayed contrast-enhanced cardiac magnetic resonance imaging. The 17 subjects who developed RBBB tended to have larger infarcts (creatine kinase-MB 251 ± 92 vs 148 ± 97 IU, p = 0.03; cardiac magnetic resonance imaging mass 22.5 ± 9.3 vs 16.6 ± 8.3 g, p = 0.1) and were more likely to have sustained anterior and inferior septal transmural infarctions (9 of 17 vs 1 of 10, p = 0.03) than those without RBBB. Those who developed RBBB had greater LV mass reductions at 6 months (46 ± 26 vs 29 ± 13 g, p = 0.04) despite similar reductions in LV pressure gradients (64 ± 31 vs 56 ± 32 mm Hg). In conclusion, patients who develop RBBB after ASA tend to have more extensive transmural septal infarctions and greater reverse remodeling than those without RBBB.