Type 2 Myocardial Infarction and Long-Term Mortality Risk Factors: A Retrospective Cohort Study

Abstract

Introduction: In-hospital risk factors for type 1 myocardial infarction (MI) have been extensively investigated, but risk factors for type 2 MI are still emerging. Moreover, type 2 MI remains an underdiagnosed and under-researched condition. Our aim was to assess survival rates after type 2 MI and to analyze the risk factors for patient prognosis after hospitalization.

Methods: We conducted a retrospective database analysis of patients with MI diagnosis who were treated in Vilnius University Hospital Santaros Klinikos. A total of 6495 patients with the diagnosis of MI were screened. The primary study endpoint was long-term all-cause mortality. The predictive value of laboratory tests was estimated including blood hemoglobin, D dimer, creatinine, brain natriuretic peptide (BNP), C-reactive protein (CRP), and troponin levels.

Results: Out of all the patients diagnosed with MI there were 129 cases of type 2 MI (1.98%). Death rate almost doubled from 19.4% at 6 months to 36.4% after 2 years of follow-up. Higher age and impaired kidney function were risk factors for death both during hospitalization and after 2 years of follow-up. Lower hemoglobin (116.6 vs. 98.9 g/L), higher creatinine (90 vs. 161.9 μmol/L), higher CRP (31.4 vs. 63.3 mg/l), BNP (707.9 vs. 2999.3 ng/L), and lower left ventricle ejection fraction were all predictors of worse survival after 2 years of follow-up. Preventive medication during hospitalization can decrease the mortality risk: angiotensin-converting enzyme inhibitor (ACEi) (HR 0.485, 95% CI 0.286-0.820) and statins (HR 0.549, 95% CI 0.335-0.900). No significant influence was found for beta blockers (HR 0.662, 95% CI 0.371-1.181) or aspirin (HR 0.901, 95% CI 0.527-1.539).

Conclusions: There is significant underdiagnosis of type 2 MI (1.98% out of all MIs). If the patient is prescribed a preventive medication like ACEi or statins, the mortality risk is lower. Increased awareness of elevation of laboratory results could help to improve the treatment of these patients and identify the most vulnerable groups.

Keywords: Acute cardiovascular events; BNP; Cardiovascular outcomes; Troponin; Type 2 myocardial infarction.