Characteristics and Outcomes of Early Recurrent Myocardial Infarction After Acute Myocardial Infarction

Abstract

Background We aimed to understand the characteristics and outcomes of patients readmitted with a recurrent myocardial infarction (RMI) within 90 days of discharge after an acute myocardial infarction (early RMI). Methods and Results We analyzed the timing of reinfarction, etiology, and outcome for all patients admitted with an early RMI within 90 days of discharge after an acute myocardial infarction between January 1, 2010 and January 1, 2017. We identified 6626 admissions for acute myocardial infarction (index myocardial infarction) which led to 168 cases of RMI within 90 days of discharge. The mean patient age was 65.1±13.1 years, and 37% were women. The 90-day probability of readmission with an early RMI was 2.5%. Black race, medical management, higher troponin T, and shorter length of stay were independent predictors of early RMI. Medically managed group had a higher risk for early RMI compared with percutaneous coronary intervention (P=0.04) or coronary artery bypass grafting (P=0.2). Predominant mechanisms for reinfarction were stent thrombosis (17%), disease progression (12%), and unchanged coronary artery disease (11%). At 5 years, the all-cause mortality rate for patients with an early RMI was 49% (95% CI, 40%-57%) compared with 22% (95% CI, 21%-23%) for patients without an early RMI (P<0.0001). Conclusions Early RMI is a life-threatening condition with nearly 50% mortality within 5 years. Stent-related events and progression in coronary artery disease account for most early RMI. Medication compliance, aggressive risk factor management, and care transitions should be the cornerstone in preventing early RMI.

Keywords: coronary artery disease; early recurrent myocardial infarction; readmission; reinfarction; stent thrombosis.

Figure 1. Causes of early recurrent myocardial infarction after acute myocardial infarction.

Out of 55 patients who did not undergo catheterization, 12 had type 2 myocardial infarction, 7 had known multivessel disease and hence underwent coronary artery bypass grafting and the reason for recurrent myocardial infarction for the remaining 36 is unknown. CABG indicates coronary artery bypass grafting; CAD, coronary artery disease; LHC, left heart catheterization; MI, myocardial infarction; and PCI, percutaneous coronary intervention.

Figure 2. Timing of early recurrent myocardial infarction (RMI) and relationship with index myocardial infarction treatment strategies.

A, Timing of readmission with early RMI. Instantaneous risk (hazard function, or rate) of readmission for early RMI (RMI, solid line) enclosed within dashed 68% confidence bands. Note that early peaking hazard followed by a slightly increasing risk (almost constant risk at a rate of about 0.01 readmissions for myocardial infarction per patient per month). B, Relationship between index myocardial infarction treatment strategy and risk of early RMI. Instantaneous risk (or rate) of readmissions for early RMI hazard after admission for acute myocardial infarction stratified by treatment strategy. Solid line is the parametric estimates of the instantaneous risk of readmission for myocardial infarction enclosed within a 68% CI. MI indicates myocardial infarction.

Figure 3. Outcomes of patients with an early recurrent myocardial infarction (RMI).

A, Survival analysis of patients with and without early RMI^*. ^*Time zero for patients with RMI (blue curve) is time of RMI; and time zero for patients without RMI is 90 days after index admission for myocardial infarction. B, Survival analysis of patients with early RMI with non‒ST‐segment‒elevation myocardial infarction/ST‐segment–elevation myocardial infarction.^{+ +}Time zero for this analysis is the time of RMI. NSTEMI indicates non‒ST‐segment‒elevation myocardial infarction; RMI, recurrent myocardial infarction; and STEMI, ST‐segment–elevation myocardial infarction.