Septal perforator anatomy and variability of perfusion bed by myocardial contrast echocardiography: A study of hypertrophic cardiomyopathy patients undergoing alcohol septal ablation

Objective To characterize the perfusion bed of the first septal perforator by myocardial contrast echocardiography (MCE) in patients with hypertrophic cardiomyopathy undergoing alcohol septal ablation (ASA). Background MCE is used to define the septal perforator anatomy prior to ASA. Occasionally, ASA cannot be performed due to unfavorable septal anatomy or perfusion outside the interventricular septum. Despite the standard use of MCE for septal mapping, there are no reports describing the territory of septal perforator perfusion. Methods Forty-seven consecutive patients underwent ASA between 1/1/2004 and 12/30/2012. Blinded individuals retrospectively evaluated patients for septal perforator anatomic findings. Patients were divided into 2 groups based on presence or absence of extra-septal perfusion (ESP) as visualized by apical views after intracoronary contrast injection. The groups' procedural outcomes were compared, including infarct size, new conduction abnormalities, and major adverse events. Results Over 25% demonstrated ESP, of which 83% predominantly involved the right ventricular (RV) moderator band. The first septal perforator (FSP) was statistically larger in ostial diameter (1.69 mm vs. 1.23 mm, P = 0.04) and numerically more likely dominant in patients with ESP (63.6% vs. 47.2%, P = 0.22). In those with ESP, the odds ratio comparing FSP diameter of 2.0 mm to the mean was 1.96 (95% CI: 1.01-3.80). Conclusions Downstream capillary perfusion may be discordant from epicardial territory and this study emphasizes the importance of MCE prior to ASA. Over 25% of our patients demonstrated ESP, most commonly involving the RV moderator band. The size of the FSP was the strongest predictor of ESP.