The spectrum of coronary artery disease and risk of myocardial infarction  

Clinicians often dichotomize coronary artery disease (CAD) on the basis of obstruction to blood flow given the implications of this threshold on considerations for revascularization. As a result, nonobstructive CAD is often characterized as less significant, although this may oversimplify the risks associated with nonobstructive disease. In this retrospective cohort of patients who underwent elective coronary angiography in the Veterans Affairs health care system, the authors evaluated the relationship between gradations of CAD burden and 1-year outcomes of non-fatal myocardial infarction (MI) and mortality. CAD burden was defined by both thresholds for no CAD, nonobstructive CAD, and obstructive CAD as well as the number of vessels involved (1-vessel, 2-vessel, or 3-vessel/left main). Among 37,674 patients who underwent elective angiography, 22.3% had non-obstructive CAD and 55.4% had obstructive CAD. Compared with patients with no CAD, risk adjusted 1-year MI rates progressively increased with greater CAD burden [1-vessel nonobstructive (HR 2.0; 95%CI, 0.8-5.1); 2-vessel nonobstructive (HR 4.6; 95%CI, 2.0-10.5); 3-vessel nonobstructive (HR 4.5; 95% CI, 1.6-12.5), 1-vessel obstructive (HR 9.0; 95% CI, 4.2-19); 2-vessel obstructive (HR 16.5; 95% CI, 8.1-33.7); 3-vessel/left main obstructive (HR 19.5; 95% CI, 9.9-38.2)]. Risk adjusted 1-year mortality was also significantly higher among patients with 3-vessel nonobstructive CAD and any level of obstructive CAD.

 Conclusion: This study highlights that CAD is not a dichotomous disease that is either present or absent, but is a spectrum of progressive disease with corresponding risk. Greater attention to the spectrum of CAD risk may result in better patient outcomes.

Summarized by Lauren E. Thompson

Nonobstructive Coronary Artery Disease and Risk of Myocardial Infarction. Maddox TM, Stanislawski MA, Grunwald GK, Bradley SM, Ho PM, Tsai TT, Patel MR, Sandhu A, Valle J, Magid DJ, Leon B, Bhatt DL, Fihn SD, Rumsfeld JS. JAMA. 2014;312(17):1754-1763. doi:10.1001/jama.2014.14681.