Dobutamine stress echocardiography related sustained ventricular tachycardia in a patient with ischemic cardiomyopathy

Abstract

A 66 year-old Asian man; with a complex history of ischaemic heart disease presented with cardiac and troponin negative chest pain. His ECG showed sinus bradycardia with old left bundle branch block. The transthoracic echocardiography showed severely impaired left ventricular systolic function (EF 30-35%). The patient had had coronary artery bypass grafting at age of 42 years and remained asymptomatic until age of 56 years when he presented with incessant ventricular tachycardia requiring amiodarone, lidocaine and electrical cardioversion. Coronary angiography at that time showed occluded vein grafts to the circumflex and diagonal arteries. The right coronary artery (RCA) was small and received collaterals from the left system. A myocardial perfusion scan showed extensive inferolateral infarction but no evidence for reversible ischaemia. An implantable cardiac defibrillator (ICD) was thus inserted. Over the following years, the patient underwent multiple PCI procedures with rotational atherectomy to the native LAD and associated vein graft, but subsequently developed in-stent restenosis. He also had PCI to the native RCA. He declined a minimally invasive grafting of the left internal mammary artery (LIMA) to the LAD and re-implantation of a new ICD after ex-plantation of the original one due to sepsis. His coronary artery disease remained stable following a recent admission with Troponin positive event which was confirmed by a repeat angiogram, therefore, had up-titrated anti-anginal medications. A low dose beta-blockade was discontinued due to documented sinus pauses up to 3 seconds. Following the recent admission, a joint cardiology-cardiothoracic meeting discussion recommended a stress echocardiogram with highdose dobutamine to guide towards considering re-do bypass grafting. A dobutamine stress echocardiogram (DSE) was performed (40 mcg/kg/min + 300 mcg atropine) by an experienced operator and the patient achieved 84% of target heart rate. At peak stress, he experienced hot sensation in the chest for which he was given GTN spray. Study analysis confirmed no evidence of inducible ischaemia (Figure 1), but three minutes into recovery, he developed sustained ventricular tachycardia at a rate of 218 bpm (Figure 2), but without obvious haemodynamic compromise. Intravenous metoprolol and amiodarone were administered and sinus rhythm was restored after approximately twenty minutes. The patient was observed overnight in CCU, and discharged few days later with a plan to refractory angina clinic referral in a tertiary centre, and to be assessed by an electrophysiologist for potential device therapy.