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 Recovery: Role 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 follows: class 1, plaque-mediated culprit lesion (82.5% of women; 94.9% of men); class 2, obstructive coronary artery disease with supply-demand mismatch (2a: 1.4% women; 0.9% men) and without supply-demand mismatch (2b: 2.4% women; 1.1% men); class 3, nonobstructive coronary artery disease with supply-demand mismatch (3a: 4.3% women; 0.8% men) and without supply-demand mismatch (3b: 7.0% 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.