The Variation in Recovery: Role of Gender on Outcomes of Young AMI Patients (VIRGO) Classification System: A Taxonomy for Young Women With Acute Myocardial Infarction

BACKGROUND—Current classification schemes for acute myocardial infarction (AMI) may not accommodate the breadth of clinical phenotypes in young women. METHODS AND RESULTS—We developed a novel taxonomy among young adults (≤55 years) with AMI enrolled in the Variation in RecoveryRole of Gender on Outcomes of Young AMI Patients (VIRGO) study. We first classified a subset of patients (n=600) according to the Third Universal Definition of MI using a structured abstraction tool. There was heterogeneity within type 2 AMI, and 54 patients (9%; including 51 of 412 women) were unclassified. Using an inductive approach, we iteratively grouped patients with shared clinical characteristics, with the aims of developing a more inclusive taxonomy that could distinguish unique clinical phenotypes. The final VIRGO taxonomy classified 2802 study participants as followsclass 1, plaque-mediated culprit lesion (82.5% of women; 94.9% of men); class 2, obstructive coronary artery disease with supply-demand mismatch (2a1.4% women; 0.9% men) and without supply-demand mismatch (2b2.4% women; 1.1% men); class 3, nonobstructive coronary artery disease with supply-demand mismatch (3a4.3% women; 0.8% men) and without supply-demand mismatch (3b7.0% women; 1.9% men); class 4, other identifiable mechanism (spontaneous dissection, vasospasm, embolism; 1.5% women, 0.2% men); and class 5, undetermined classification (0.8% women, 0.2% men). CONCLUSIONS—Approximately 1 in 8 young women with AMI is unclassified by the Universal Definition of MI. We propose a more inclusive taxonomy that could serve as a framework for understanding biological disease mechanisms, therapeutic efficacy, and prognosis in this population.