Apart from the timing of CABG, the outcomes of STEMI patients undergoing CABG depend on baseline demographic variables. Those with mechanical complications of STEMI (eg, ventricular septal rupture or mitral regurgitation caused by papillary muscle rupture) have a high operative mortality rate.240 242,244,255,267 In a study of 641 subjects with ACS, 22 with evolving STEMI and 20 with a mechanical complication of STEMI were referred for emergency CABG; the 30-day mortality rate was 0% in those with evolving STEMI and 25% in those with a mechanical complication of STEMI.268 In those with mechanical complications, several variables were predictive of death, including advanced age, female sex, cardiogenic shock, the use of intra-aortic balloon counterpul- sation preoperatively, pulmonary disease, renal insufficiency, and magnitude of elevation of the serum troponin 2.2.2. Life-Threatening Ventricular Arrhythmias: Recommendations Class I 1. CABG is recommended in patients with resuscitated sudden cardiac death or sustained ventricular tachycardia thought to be caused by significant CAD (>50% stenosis of left main coronary artery and/or >70% stenosis of 1, 2, or all 3 epicardial coronary arteries) and resultant myocardial ischemia.248,271,272 (Level of Evidence: B) Class III: HARM 1. CABG should not be performed in patients with ventricular tachycardia with scar and no evidence of ischemia. (Level of Evidence: C) See Online Data Supplement 6 for additional data on life- threatening ventricular arrhythmias. Most studies evaluating the benefits of CABG in patients with ventricular arrhythmias have examined survivors of out-of-hospital cardiac arrest as well as patients with induc- ible ventricular tachycardia or fibrillation during electro- physiological study.272 274 In general, CABG has been more effective in reducing the occurrence of ventricular fibrillation than of ventricular tachycardia, because the mechanism of the latter is usually reentry with scarred endocardium rather than ischemia. 