Non-surgical septal reduction therapy in hypertrophic obstructive cardiomyopathy: current practice and future potential

Obstruction in hypertrophic cardiomyopathy is associated with increased morbidity and mortality. Effective resolution of outflow tract obstruction can provide relief of symptoms and perhaps improve prognosis. Non-surgical septal reduction in the form of alcohol septal ablation (ASA) has been performed since 1994 with limited progress in the last decade. ASA using traditional methods has an unacceptably high rate of failure to resolve LVOT gradient. By creating and populating a relational database I was able to show that failure to treat LVOT gradient satisfactorily was seen in 41% after one procedure and 18% after multiple procedures. This can be partly explained by inaccurate location of the iatrogenic infarction, seen on CMR. Improving accuracy of infarction in ASA could be achieved by better peri-procedural imaging. Intracardiac echocardiography (ICE) provides excellent image quality of the contact point of the mitral valve on the septum in HOCM, but is no better than standard transthoracic echocardiography in describing detail of the septum or other cardiac structures relevant to ASA. ICE cannot see myocardial contrast well and therefore cannot be used to guide ASA alone. Computed tomography (CT) angiography can visualise small septal arteries. The ability to merge angiographic images with structural detail allows description of the path of arteries to guide alcohol injection in ASA. The use of CT planning improved the success rate of ASA after one procedure from 59% to 85%. We observed less RBBB (13% vs 62%) due to improved targeting of the LV septum, confirmed by CMR. Patient selection in ASA is important. A standard operating procedure for assessment and treatment of HOCM patients is now part of routine clinical care. Some patients cannot receive trans-coronary alcohol due to arterial anatomical restrictions. Direct endocardial radiofrequency ablation of the interventricular septum with merged ICE/CARTO electrophysiology mapping system guidance was explored with encouraging results.Open Acces