More than one third of the patients had a ventricular tachyarrhythmia within the last hour of life. Cardiac death was the primary cause and heart failure the specific cause of death in the majority of the cases. Devices remained active in more than half of the patients with a do-not-resuscitate order; almost one fourth of these patients received at least 1 shock in the last 24 hours of life.

Guidelines advocate primary preventive ICDs for patients with LVEF ≤35% after >40 days after AMI, but a delay of at least 3 months is recommended after revascularization. Implantation of primary preventive ICDs is also recommended for patients with LVEF ≤40%, nonsustained ventricular arrhythmias (ventricular tachyarrhythmias) caused by prior AMI, and inducible ventricular tachyarrhythmias during electrophysiological studies. 13 The optimal timing for ICD implantation has not been evaluated in prospective studies.14 A substudy of Multicenter Automatic Defibrillator Implantation Trial (MADIT) II showed more benefit with ICD in patients with more remote AMI, 15 but post hoc analysis of the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) study implicates that the duration after AMI does not modify Background-Implantable cardioverter-defibrillator therapy improves survival in patients with reduced left ventricular ejection fraction (LVEF) after acute myocardial infarction (AMI). Although the risk of sudden cardiac death is highest in the first month after AMI, there is no survival benefit of early implantable cardioverter-defibrillator implantation, and the optimal time frame has yet to be established. Thus, the aim of this study was to investigate what proportion of post-AMI patients had improved LV function to such an extent that the indication for implantable cardioverter-defibrillator was no longer present. Methods and Results-Patients admitted for AMI with reduced LVEF (≤40%) were eligible for inclusion. Repeat echocardiographic examinations were performed 5 days, 1 month, and 3 months after the AMI. We prospectively included 100 patients with LVEF of 31±5.8% after AMI. At the 1-month follow-up, 55% had an LVEF >35%. The main improvement in LVEF had occurred by 1 month. The mean difference in LVEF over the next 2 months was small, 1.9 percentage units. During the first 9 weeks, 10% of the patients suffered from life-threatening arrhythmias. Conclusions-Most patients have improved LVEF after AMI, and in the majority, the improvement can be confirmed after 1 month, implying that further delay of implantable cardioverter-defibrillator implantation may not be warranted. The aim of this study was to investigate what proportion of patients with reduced LV function after an AMI reached an LVEF >35%, thereby no longer qualifying for ICD treatment. We also investigated the time to improvement to allow earlier identification of possible ICD candidates. MethodsPatients admitted with AMI at Danderyd University Hospital or Södersjukhuset in Stockholm between November 2010 and December 2013 were eligible for participation in the study if a clinical echocardiography showed an LVEF of ≤40%. An AMI was defined according to the second and third universal definitions of myocardial infarction. 19,20 All clinical echocardiographies of potentially eligible patients were reviewed by a participating research cardiologist with echocardiographic expertise who confirmed that the LVEF was indeed ≤40% according to the modified Simpso...

The follow-up of post-myocardial infarction patients with left ventricular dysfunction according to guidelines was insufficient in this population and may have increased the risk for SCD. A significant proportion of patients experienced improved left ventricular function during short-term follow-up making preventive ICD treatment redundant.