Type 2 versus type 1 myocardial infarction: a comparison of clinical characteristics and outcomes with a meta-analysis of observational studies

Abstract

Background: Type 2 myocardial infarction (MI) is an imbalance between myocardial oxygen demand and supply, leading to myocardial ischemia. It is not due to plaque rupture, and is usually caused by a condition other than coronary artery disease (CAD). However, limited data are available comparing the prevalence of traditional coronary risk factors and mortality between type 1 and type 2 MI. We hypothesize that type 2 MI carries a higher mortality than type 1. Methods:We searched the databases of PubMed, EMBASE, CENTRAL, and MEDLINE for studies comparing type 1 MI with type 2 MI. The baseline variables were compared in each cohort. Summary risk ratios and 95% confidence intervals were calculated using the random effects model to compare mortality between the two groups. Results:The included studies yielded 25,872 patients of whom 2,683 (10%) had type 2 MI. Compared to the type 1 cohort, the type 2 cohort had significantly higher inpatient (15% vs. 4.7%, P<0.00001), 30-day (17.6% vs. 5.3%, P<0.00001) and 1-yr mortality (27% vs. 13%, P<0.00001), as well as higher 30-day major adverse cardiovascular events (20% vs. 9%, P<0.0001). Operative stress (20%) was the most common trigger of type 2 MI, followed by sepsis (19%), arrhythmia (18.63%), heart failure (15%), and anemia (12%).Conclusions: Type 2 MI is a common entity and is more common in females, older age groups, and in patients with multiple comorbidities: it also tends to result in higher mortality.

A systematic review on the triggers and clinical features of type 2 myocardial infarction

“…In the TRACER trial, the most frequent potential provoking factor for T2MI was tachyarrhythmia (38.2%), which is consistent with our findings . A meta‐analysis also demonstrated that the most common associated arrhythmia was tachyarrhythmia, especially atrial fibrillation, in patients with T2MI . Most patients with T2MI died from noncardiovascular causes during long‐term follow‐up.…”

“…In this review, most selected studies revealed that the number of men with T2MI was higher than that of women, while a reduced number of studies found the opposite . For example, Gupta et al described T2MI was more common in females compared with T1MI . Among the clinical characteristics of T2MI, we concluded that cardiovascular risk factors or comorbidities might be the most important causes of T2MI and affect the prognosis in these patients.…”

Defining and managing patients with non‐ST‐elevation myocardial infarction: Sorting through type 1 vs other types

“…Both type 1 and type 2 MI can present as NSTEMI or STEMI, although NSTEMI is more common for both types . Most NSTEMI pathophysiologically are consistent with type 1 MI, but the relative proportions of type 1 NSTEMI and type 2 NSTEMI vary between clinical settings …”

“…NSTEMI is more common than STEMI, although the proportion of patients with STEMI is higher for type 1 MI than type 2 . A meta‐analysis of observational studies comparing type 1 and type 2 MI showed that 70.0% of the 2683 patients with type 2 MI were diagnosed with NSTEMI compared with 44.1% of 23 189 patients with type 1 MI . A prospective study of consecutive patients meeting the definition of MI found that 96.7% of the 144 patients with type 2 MI had NSTEMI, compared with 67.3% of the 397 patients with type 1 MI .…”

“…Underlying conditions that may predispose individuals to oxygen supply‐demand imbalances, and thus type 2 MI, include hypotension, sepsis, anemia, tachyarrhythmia, respiratory failure, and hypertension . In addition to CV differences, a number of studies have shown that patients who have a type 2 MI are usually older, more often women, and more likely to have a history of comorbidities such as heart failure, arrhythmias, chronic obstructive pulmonary disease, or renal impairment …”