A 45-year-old patient with an implantable cardioverter defibrillator and a decreased left ventricular (LV) ejection fraction (40%) due to non-ischaemic cardiomyopathy was referred for ablation of recurrent LV outflow tract tachycardia. Endocardial and coronary venous mapping revealed earliest electrical activation within the distal great cardiac vein (GCV). Endocardial LV ablation was unsuccessful and ablation from the distal GCV was abandoned due to high impedance. Using a subxiphoid approach, epicardial mapping revealed earliest electrical activation at the LV epicardial surface superior to the GCV in close proximity to the proximal left circumflex artery. To minimize the risk of thermal injury to that vessel, epicardial catheter ablation was performed during repeated simultaneous left coronary angiography (see figure). Epicardial radiofrequency ablation starting at 5 W terminated the ventricular tachycardia (VT) and was titrated to 20 W without evidence of injury to the coronary arteries. During the 6 months follow-up, the patient was free from VT under continued amiodarone therapy without signs of coronary artery disease.
The region of the LV epicardial surface bounded by the left coronary arteries that lies superior to the aortic portion of the LV outflow tract has been termed the LV summit. An area superior to the GCV has been termed the ‘inaccessible area’ because of the close proximity to the coronary arteries and the thick layer of epicardial fat. In our patient, repeated simultaneous coronary angiography allowed continuous monitoring of coronary artery patency and careful titration of radiofrequency energy for successful ablation of the LV summit tachycardia in the ‘inaccessible area’.
The full-length version of this report can be viewed at: http://www.escardio.org/communities/EHRA/publications/ep-case-reports/Documents/Coronary-angiography-lv-summit-tachycardia.pdf
