Background: In patients with apparently normal hearts, ventricular tachycardia (VT) may only involve the subepicardial myocardium.
Methods and results: Four patients with exercise-induced fast VT with right bundle branch block morphology were investigated. ECG showed a small q wave in leads II, III, and aVF during sinus rhythm (SR) in all 4 patients. Left ventricular angiography showed small inferolateral aneurysms in all patients. Coronary arteriograms were normal in all 4 patients. Six unstable VTs (cycle length, 200 to 305 ms) and 1 stable VT (cycle length 370 ms) were reproducibly induced in the 4 patients. During SR, endocardial mapping was normal in all 4 patients, and epicardial mapping showed fragmented and late potentials in the left inferolateral wall anatomically consistent with the left ventricle aneurysm. During tachycardia, epicardial mapping showed a macroreentrant VT with focal endocardial activation in the patient with stable VT, whereas in 2 patients with unstable VT, a diastolic potential was only recorded and coincided with the late potential in the same area. Epicardial ablation was performed in 3 patients and successfully abolished those VTs. No VT recurred in 2 patients during follow-up of 2 and 9 months. Clinical VT recurred 6 months after the ablation and was successfully ablated in a repeated epicardial ablation in 1 patient. In the remaining patient without epicardial ablation, an implantable cardiac defibrillator was implanted. There were multiple shocks during a follow-up of 31 months.
Conclusions: In patients with normal coronary arteriograms and left ventricle aneurysm, exercise-induced VT with right bundle branch block morphology may have a subepicardial arrhythmogenic substrate, which may be amenable to epicardial ablation.