Use of Cardiac MRI in Early Stages of STEMI to Predict Left Ventricular Function Recovery and ICD Implantation

Overview

Patients presenting with STEMI and late revascularization can suffer from severe left ventricular dysfunction. Midterm and longterm mortality can be determined by the risk of fatal ventricular arrythmias. For this specific population, ESC guidelines currently recommend a waiting period of up to 40 days after a STEMI with severe left ventricular dysfunction before considering ICD implantation for primary prevention of sudden death.This delay is allocated to judge left ventricular recovery. This study aims to see whether early cardiac MRI with specific sequences can help predict which patients will most probably not recover their left ventricular function and benefit from earlier ICD implantation.

ST segment elevation myocardial infarction represent 120 000 annual cases in France. Although its mortality has been drastically reduced by primary percutaneous coronary angioplasty (PCI), its midterm and longterm outcome in patients presenting initially with severe left ventricular (LV) dysfunction depends on the risks of heart failure and sudden death by malignant ventricular arrhythmias. Many clinical studies such as MADIT I and II, MUSTT and DINAMIT have participated in defining which patients should benefit from ICD implantation. These studies were based on evaluation of the LV ejection fraction (LVEF) and of the risk of arrhythmia (by electrophysiology or holter recordings). However, ESC Guidelines recommend a mandatory waiting period of 40 days post-PCI to reevaluate LVEF before confirming the need for ICD implantation (LVEF \< 35%). Therefore, patients are at risk of sudden cardiac death (SCD). during this period. The investigators sought to determine whether specific cardiac MRI sequences could help predict which patients would eventually recover from their LV dysfunction and therefore reduce the risk of SCD by implanting ICD earlier than recommended. Patients presenting at our Cardiac ICU with STEMI and severe LV dysfunction (LVEF \< 35%), not indicated to coronary artery bypass surgery (CABG) and free from initial cardiac arrest or severe ventricular arrhythmias, will be included. They will undergo a gadolinium-enhanced cardiac MRI during the 1st days of hospitalization with specific sequences to determine myocardial zones at risk of non-recovery. Initial assessment will also include thorough clinical examination with NYHA class, trans-thoracic echocardiography and blood works to evaluate renal function, inflammation, signs of heart failyre (BNP and troponin). Patients will be equipped with Lifevests for 6 weeks and followed-up with the same criteria. Ratio of final ICD implantation will then be compared to the MRI criterion to determine whether LV recovery could have been predicted.