Young and older patients with acute myocardial infarction: differences in risk factors and angiographic characteristics.

Abstract

Objective: Although coronary artery disease mainly affects older individuals, the incidence of myocardial infarction (MI) among younger adults (<55 years) has increased during the past decade. Young and older MI patients have different underlying pathophysiologic characteristics, atherosclerotic plaque morphology, and risk factor profiles.

Methods: We studied 977 patients (≤55 years old: 322, >55 years old: 655) who were hospitalized for MI in the previous 5 years. Patients' baseline characteristics and daily habits were recorded. Angiographic characteristics and vascular lesions were detected, and further examinations, including flow-mediated dilation (FMD), pulse wave velocity (PWV), and central augmentation index (AIx), were performed. Biomarkers of inflammation (Interleukin-6, Tumor-Necrosis factor-a, Intercellular Adhesion Molecule 1, and Osteopontin) were also tested.

Results: The median age in the younger age group was 49 years [interquartile range (IQR: 44-53)] and 66 years (IQR: 61-73) in the older age group. Arterial hypertension was less prevalent in the young compared to the elderly with MI (47.4% vs. 76.2%, p < 0.01). The younger counterparts presented significantly lower rates of diabetes mellitus (19.3% vs. 30.6%, p < 0.01), dyslipidemia (59% vs. 70.8%, p < 0.01), and atrial fibrillation (2.6% vs. 9.7%, p < 0.01) and were more casual smokers (49.3% vs. 23.8%, p < 0.01) compared to older patients with MI. In terms of arterial stiffness, lower PWV [7.3 m/s (IQR: 6.5-8.4 m/s) vs. 9 m/s (IQR: 8-10.8 m/s), p < 0.01] and AIx (20.5 ± 10.8 vs. 25.5 ± 7.8, p < 0.01) were recorded in the young compared to the elderly with MI. Concerning angiographic characteristics, younger patients were more likely to have none or single-vessel disease (55.6% vs. 45.8%, p < 0.02), whereas the older participants more frequently had three or more vessel disease (23.5% vs. 13.6% in the young, p < 0.02). Although significant disparities in blood test results were detected during the acute phase, the great majority of young MI patients were undertreated.

Conclusion: Younger patients with MI are more likely to be smokers with impaired PWV measures, present with non-obstructive or single-vessel disease, and often remain undertreated. A better knowledge of the risk factors as well as the anatomic and pathophysiologic processes in young adults will help enhance MI prevention and treatment options in this patient population.