Outcome Prediction of Septal Ablation in Patients With Hypertrophic Cardiomyopathy

Sudden Cardiac Death in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a heart disease characterized by hypertrophy of the left ventricular myocardium and is most often caused by mutations in sarcomere genes. The structural and functional abnormalities are not explained by flow-limiting coronary artery disease or loading conditions. The disease affects at least 0.2% of the population worldwide and is the most common cause of sudden cardiac death in young people and competitive athletes because of fatal ventricular arrhythmia. In some patients, however, HCM has a benign course. Therefore, it is of utmost importance to properly evaluate patients and single out those who would benefit from an implanted cardioverter defibrillator. In this article, we review and summarize the sudden cardiac death risk stratification algorithms, methods of preventing death due to HCM, and novel factors that may improve the existing prediction models.

Alcohol septal ablation: in which patients and why?

At present, surgical septal myectomy is regarded as the "gold standard" treatment for most patients with obstructive hypertrophic cardiomyopathy (HCM) and drug-refractory symptoms. However, the best results are obtained by those surgeons who have extensive experience with this operation at a small number of referral centers. In the mid-1990s, percutaneous alcohol septal ablation was introduced as an alternative to myectomy to reduce LV outflow gradient and heart failure symptoms in patients with obstructive HCM. However, certain features of alcohol ablation limit its applicability to carefully selected patients. Because this procedure involves the injection of 1-4 mL of 96% ethanol into a septal perforator of the left anterior coronary artery to produce a myocardial infarction (with septal thinning, outflow tract widening and gradient reduction), alcohol ablation is limited by the size and distribution of the septal perforator branches. In addition, rich blood supply from other septal branches not occluded by the balloon and from the posterior descending coronary artery may restrict myocardial ischemia to portions of the septum that do not contribute to outflow obstruction. Septal hypertrophy may be either mild or particularly marked, and abnormalities of mitral valve apparatus may also play a major role in outflow obstruction. When such features are present, alcohol-induced septal thinning is unlikely to significantly reduce the gradient. In addition, persisting uncertainties regarding the risk for ventricular tachyarrhythmias after alcohol ablation suggest this procedure should be limited to patients of advanced age, patients at unacceptable operative risk due to comorbidities, or those with strong aversion to surgery. Further progress in the treatment for patients with obstructive HCM and severe refractory symptoms will come from assuring proper patient selection for alcohol septal ablation, as well as increasing the number of surgeons and centers experienced in performing septal myectomy.

Angiographic and echocardiographic correlates of suitable septal perforators for alcohol septal ablation in hypertrophic obstructive cardiomyopathy

BACKGROUND

Myocardial contrast echocardiography during angiography is critical in identifying appropriate septal perforator(s) for alcohol septal ablation (ASA) in patients with hypertrophic obstructive cardiomyopathy. We evaluated whether there were other angiographic and/or echocardiographic markers that might identify patients who are anatomically suitable for ASA.

METHODS

We performed quantitative coronary angiographic analysis and echocardiographic assessment on 74 patients referred for ASA from January 2004 to July 2012 at the Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada. Patients who proceeded to ASA were compared with those in whom ASA was aborted.

RESULTS

Of the 74 patients referred for ASA, 63 proceeded to ASA and in 11 patients ASA was aborted because of various anatomic and technical reasons. There were no clinically significant differences observed in quantitative angiographic and echocardiographic measurements between the 2 groups. The ratio of ostial left main (LM) to ablated septal distance on angiography vs the basal septum to the septum area where the mitral valve contacted the septum because of systolic anterior motion (SAM) was 1.53. In the whole cohort, a significant correlation was observed between the ostial LM to the target septal distance and the distance from basal septum to SAM-septal contact point on echocardiography (r = 0.39; P = 0.008). A stronger correlation was evident when analysis was restricted to patients undergoing ASA only (r = 0.44; P = 0.006).

CONCLUSIONS

Echocardiographic and angiographic assessments of the distance between the basal septum to SAM-septal contact point and ostial LM to the target septal distance might be useful in preprocedural selection of the appropriate septal perforator for ASA.