Abstract 2933: Early Post-Myocardial Infarction Remodeling and Subsequent Risk of Cardiac Arrest
BACKGROUND: Persistent, severe left ventricular (LV) dysfunction post myocardial infarction (MI) predicts a higher risk of adverse outcomes. Yet, severe LV dysfunction measured immediately after MI is not useful in identifying patients who benefit from a prophylactic implantable cardioverter defibrillator (ICD). Since contemporary MI interventions (revascularization, medical therapy) may greatly enhance recovery of LV function we sought to assess the relationship between recovery of LV function in the initial 2 months post-MI with subsequent risk of cardiac arrest.
METHODS: A group of 322 patients with ejection fraction (EF) values < 0.50 in the immediate post-MI period were enrolled. EF values were re-assessed 2 months post MI. The average absolute improvement in EF was 0.07 (SD 0.11). Patients were grouped by the degree of EF recovery (none, n = 106, modest [0.01 to 0.09], n = 94, and large [0.10 or greater EF increase] improvement, n = 122). During an average follow-up of 4 years 24 fatal (n=17) or non-fatal (n=7) cardiac arrests and 30 deaths were observed. The relationship between degree of LV recovery and outcome was assessed using Cox models.
RESULTS: The average age of participants was 61 years, most (85%) were male, and 75% underwent revascularization post-MI. The use of beta-blockers (94%), statins (91%), and ACE inhibitors or angiotensin receptor blockers (94%) was high. The three EF recovery groups were similar in most respects, apart from higher peak troponin values in the patients with no EF recovery (p < 0.002). A strong linear relationship (p < 0.001) in the rate of cardiac arrest over 3 years by degree of EF recovery was observed: no recovery (16.9%), modest recovery (8.3%), and large recovery (3.0%). The risk (hazard ratio) of cardiac arrest was 3.9-fold higher in patients with no EF recovery versus those with modest or large recovery, despite adjustment for important covariates, including peak troponin, revascularization and medications (p < 0.001). Similar results were observed for mortality.
CONCLUSION: Significant recovery in EF over the initial 2 months post-MI is common with contemporary management. Patients with no improvement in EF over this time period have a 3.9-fold higher risk of cardiac arrest versus patients in whom recovery occurs.