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CLINICAL STATEMENTS AND GUIDELINES

April 1, 2025 Circulation. 2025;151:e771–e862. DOI: 10.1161/CIR.0000000000001309 e820

for prophylactic ICD implantation has also been shown in patients with an LVEF ≤35% and New York Heart Association class II or III HF symptoms,1,3 as well as in patients with inducible ventricular tachycardia or ventricular fibrillation and an LVEF ≤40%1,4,13 (Table 17). 2.	 The risk of ventricular arrythmias and sudden car-

diac death is highest early after MI, although the routine implantation of a defibrillator (for primary prevention) in patients with LV dysfunction early after MI or CABG has not been associated with improved survival.14–16 In DINAMIT (Defibrillator in Acute Myocardial Infarction Trial), ICD implantation led to a 58% reduction in arrhythmic deaths within 6 to 40 days post MI with ejection fraction ≤35%; however, this was offset by an increase in nonarrhythmic deaths.16 Sustained episodes of ventricular tachycardia or ventricular fibrillation occurring >48 hours after reperfusion are associated with an increased risk of death,12,17 and the risk of sudden cardiac death is highest in the first month.5 Patients with ventricular arrhythmias should first be managed with beta blockers and/or antiarrhythmic therapy. The benefit of ICD implantation in patients with persistent or sustained ventricular arrhythmias and who are <40 days post MI remains unclear.15,16,18 A single-center observational study enrolled patients post STEMI (median, 9 days) and referred those with an LVEF ≤40% for electrophysiologic testing and implanted an ICD only in those with inducible ventricular tachycardia. Although a randomized comparator arm was unavailable, 22% of those who underwent ICD implantation had ventricular tachycardia terminated by the device during the first 12 months.6 The effects of ICD implantation on mortality cannot be definitely ascertained, and more research is required. Radiofrequency catheter ablation should be considered in patients with recurrent ventricular tachycardia or ventricular fibrillation followed by ICD implantation.19 Earlier ICD implantation can be considered in patients who have an indication for a permanent pacemaker prior to hospital discharge and in whom LVEF is not expected to recover, but no evidence was observed to definitively demonstrate the safety of this approach.10,20

3 In the VEST (Vest Prevention of Early Sudden

Death) trial, the routine use of a temporary wearable cardioverter-defibrillator did not significantly reduce the primary endpoint (composite of sudden death or death from ventricular tachyarrhythmias at 90 days) in patients with AMI and LVEF ≤35% (relative risk, 0.67 [95% CI, 0.37-1.21]).7,21 The secondary endpoint of death from any cause was lower in the wearable vest group compared with the no-device group (relative risk, 0.64 [95% CI, 0.43-0.98]); only 12 of 48 patients were wearing the device at the time of death.7 Greater benefit was demonstrated in those who were compliant with the device.21 As such, use of a wearable cardioverter-defibrillator could be considered in highrisk patients with reduced LVEF as a bridge to consideration for the need for an ICD. 4.	 Patients with STEMI with second- or third-degree

atrioventricular block have higher in-hospital mortality than those without high-degree atrioventricular block.22,23 Patients who present with ACS with complete heart block have a higher incidence of cardiogenic shock, ventricular arrhythmia, and death.24,25 In a contemporary cohort of patients with AMI, the incidence of high-degree atrioventricular block has decreased from 4.2% to 2.1%; however, increased morbidity and mortality remain despite reperfusion therapy in those with highdegree atrioventricular block.26,27 A pooled analysis of 30 000 patients found that high-degree atrioventricular block, asystole, and electromechanical dissociation are infrequent complications of NSTEMI but are associated with increased shortterm mortality. High-degree atrioventricular block is not considered to be responsible for the increased mortality but is a surrogate marker of larger infarct size.28 Temporary pacemaker insertion in the setting of ACS in patients with high-degree atrioventricular block and other pacer indications has been found to improve postdischarge survival.8,9,29 Permanent pacemaker insertion is recommended with unresolved high-degree atrioventricular block that persists >72 hours.20

9.3 Pericarditis Management After MI

Synopsis The diagnostic criteria for post-MI pericarditis are displayed in Table 18. Pericarditis that occurs early after MI typically arises 1 to 3 days after a transmural event and is presumed to be inflammatory in nature due to adjacent myocardial necrosis. These cases of early pericarditis are typically transient, lasting several days, and will resolve

Table 17.  LVEF and Patient Characteristics Defining an Indication for Prophylactic ICD Implantation for Primary Prevention in Ischemic Heart Disease

LVEF Patient Category: All Patients Should Have Expected Survival of ≥1 y ≤30% NYHA class I, II, or III2 31%-35% NYHA class II or III1,3 ≤40% Inducible VT1,4,13 ICD indicates implantable cardioverter-defibrillator; LVEF, left ventricular ejection fraction; NYHA, New York Heart Association; and VT, ventricular tachycardia.

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