Wide complex tachycardia in a patient with a dual chamber pacemaker

An 81-year-old patient was admitted to the coronary care unit due to unstable angina and respiratory distress after urgent eye surgery for retinal detachment. He had a medical history of hypertension, diabetes mellitus, coronary artery disease, and valvular heart disease. He underwent coronary artery bypass grafting and aortic valve replacement in 1998 and received a dual chamber pacemaker (Pulsar Max DR Guidant/Boston Scientific Natick, MA, USA) for third-degree heart block in 1999. The diagnosis of myocardial infarction complicated by acute pulmonary oedema was withheld, in view of a rise in troponin I level to a maximum of 14.66 µg/L (normal value <0.14 µg/L). ST-segment elevation could not be assessed because of ventricular pacing ( Figure 1A ). He developed respiratory failure for which mechanical ventilation was initiated. His echocardiography showed a depressed left ventricular function with an ejection fraction of 30% due to a large antero-lateral myocardial infarction. An urgent coronary angiography showed a critical stenosis of the left coronary artery, and a …