Recruitment status and long-term outcomes in consecutive patients with type 2 myocardial infarction: a prospective registry

Introduction Type 2 myocardial infarction (MI) is common and associated with poor prognosis. There is major heterogeneity in the diagnosis and treatment of this condition, and a lack of prospective clinical trials to inform guidelines. Purpose To compare the characteristics and clinical outcomes of patients with type 2 MI who were enrolled and those screened but not recruited into the DEMAND-MI prospective observational cohort study. Methods DEMAND-MI was a prospective observational cohort study evaluating coronary artery disease and left ventricular impairment following type 2 MI. Consecutive patients with elevation in cardiac troponin concentration were adjudicated according to the Universal Definition, forming a prospective registry of consecutive patients with type 2 MI. Registry data were linked to routine health records to determine baseline characteristics, management and clinical outcomes from screening to date of last follow up (01/07/2025) stratified by recruitment status. The primary outcome was subsequent MI or cardiovascular death. Subdistribution hazard ratios (sHR) were estimated using a Fine-Gray competing risk model accounting for non-cardiovascular death and adjusted for age and sex. Results Between January 2018 and October 2020, 660 consecutive patients with type 2 myocardial infarction were identified with 4,045 patient-years of follow-up (median 6.12 years [IQR 5.54–6.69 years]). A total of 108 patients (16%, 108/660) were eligible and recruited, with 552 (84%, 552/660) not recruited, primarily due to severe frailty (41%, 224/552), renal impairment (20%, 110/552), hepatic impairment (4%, 23/552) or critical illness (23%,128/552). Excluded patients were older (78.6 years versus 64.5 years, P < 0.001), had a longer median hospital stay (7 days versus 3 days, P < 0.001) and a greater burden of cardiovascular comorbidity (hypertension [57% versus 44%; P = 0.021]; cerebrovascular disease [22% versus 8%; P = 0.002]; heart failure [23% versus 11%; P = 0.010]). Excluded patients were at higher risk of MI or cardiovascular death (sHR 2.12, 95% CI 1.32-3.42; P = 0.002) and non-cardiovascular death (sHR 3.59, 95% CI 1.96-6.60; P < 0.001) relative to those recruited. Conclusion Patients with type 2 MI who were screened but not recruited into our cohort study were older, with a higher prevalence of co-morbidities and significantly worse clinical outcomes. Despite an excess in non-cardiovascular death, these patients were at two-fold increased risk of future MI or cardiovascular death. These findings highlight a high-risk population underrepresented in studies and underscore the need for careful consideration of inclusion criteria in future clinical trials.