Nonobstructive Coronary Artery Disease and Risk of Myocardial Infarction
Are there differences in rates of myocardial infarction (MI) and mortality among patients with nonobstructive coronary artery disease (CAD), obstructive CAD, and nonapparent CAD?
Data from a larger retrospective cohort study of US veterans were used for the present analysis. Men and women undergoing elective coronary angiography between October 2007 and September 2012 in the Veterans Affairs health care system were included in the study population. Patients with prior CAD events were excluded. Severity of CAD was grouped into: 1) no apparent CAD: no stenosis >20%; 2) nonobstructive CAD: ≥1 stenosis ≥20% but no stenosis ≥70%; and 3) obstructive CAD: any stenosis ≥70% or left main [LM] stenosis ≥50%) and distribution (one-, two-, or three-vessel CAD). The primary outcomes of interest included 1-year hospitalization for nonfatal MI after the index angiography. Secondary outcomes included 1-year all-cause mortality and combined 1-year MI and mortality.
A total of 37,674 patients were included, of which 8,384 patients (22.3%) had nonobstructive CAD and 20,899 patients (55.4%) had obstructive CAD. Within 1 year, 845 patients died and 385 were re-hospitalized for MI. After adjustment for potential confounders, 1-year MI rates increased with increasing CAD extent. Relative to patients with no apparent CAD, patients with one-vessel nonobstructive CAD had a hazard ratio (HR) for 1-year MI of 2.0 (95% CI, 0.8-5.1); two-vessel nonobstructive HR, 4.6 (95% CI, 2.0-10.5); three-vessel nonobstructive HR, 4.5 (95% CI, 1.6-12.5); one-vessel obstructive HR, 9.0 (95% CI, 4.2-19.0); two-vessel obstructive HR, 16.5 (95% CI, 8.1-33.7); and three-vessel or LM obstructive HR, 19.5 (95% CI, 9.9-38.2). One-year mortality rates were associated with increasing CAD extent, ranging from 1.38% among patients without apparent CAD to 4.30% with three-vessel or LM obstructive CAD. After risk adjustment, there was no significant association between one- or two-vessel nonobstructive CAD and mortality, but there were significant associations with mortality for three-vessel nonobstructive CAD (HR, 1.6; 95% CI,1.1-2.5), one-vessel obstructive CAD (HR, 1.9; 95% CI, 1.4-2.6), two-vessel obstructive CAD (HR, 2.8; 95% CI, 2.1-3.7), and three-vessel or LM obstructive CAD (HR, 3.4; 95% CI, 2.6-4.4). Similar associations were noted with the combined outcome.
The investigators concluded that among patients undergoing elective coronary angiography, degree of CAD was associated with worse outcomes. Those with nonobstructive CAD were at increased risk compared to those with no apparent CAD.
These data suggest that aggressive prevention management is warranted among those with nonobstructive CAD.
Keywords: Myocardial Infarction, Veterans, Coronary Angiography, Constriction, Pathologic, Hospitalization, Risk Adjustment
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