Premature ventricular complexes, non- sustained VT not associated with hemodynamic compromise, and accelerated idioventricular rhythms that emerge after reperfusion are not indicative of increased SCD risk and do not require specific therapy in the acute phase of STEMI. 9.5.2. Implantable Cardioverter-Defibrillator Therapy Before Discharge Class I 1. Implantable cardioverter-defibrillator (ICD) therapy is indicated before discharge in patients who develop sustained VT/VF more than 48 hours after STEMI, provided the arrhythmia is not due to transient or reversible ischemia, reinfarction, or metabolic ab- (Level of Evidence: B) Life-threatening ventricular arrhythmias that occur >48 hours after STEMI usually are associated with signifi- cant LV systolic dysfunction and signify poor prognosis. Although previous RCTs492,494,495 have not specifically addressed this population of patients with STEMI, they have shown clear and consistent benefit of ICD therapy for survivors of sustained VT or VF arrest.493 In the absence of a reversible cause, late (>48 hours) in-hospital sustained VT/VF is an indication for ICD therapy for secondary prevention of SCD. For other at-risk patients, particularly those with significantly reduced left ventricular ejection fraction (LVEF), candidacy for ICD therapy for primary prevention of SCD should be reassessed at 40 days after discharge (Section 10.3). See the 2008 ACCF/AHA/HRS Guidelines for Device-Based Therapy of Cardiac Rhythm 9.5.3. AF and Other Supraventricular Tachyarrhythmias AF, atrial flutter, and other supraventricular tachyarrhythmias occur frequently in patients with STEMI and are triggered by excessive sympathetic stimulation, atrial stretch due to LV or RV volume/pressure overload, atrial infarction, pericarditis, electrolyte abnormalities, hypoxia, or underlying lung dis- ease. By far the most common supraventricular arrhythmia is AF, which occurs in 8% to 22% of patients with STEMI, with higher rates in elderly patients and those with HF and hyper- tension. 