The traditional focus of cardiac care on obstructive coronary artery disease (CAD) may distract from the potential cardiac risks inherent in non-obstructive CAD. However, surprisingly little is known about adverse events among patients with non-obstructive CAD.
To evaluate myocardial infarction (MI) and all-cause mortality rates among patients with non-obstructive CAD compared to those with obstructive CAD and no CAD in a national cohort.
Design, Setting, and Participants: Retrospective cohort study of Aall U.S. veterans undergoing elective coronary angiography for CAD indications between October 2007 and September 2012 in the VA health care system.
Exposure: CAD extent at index angiography, defined by CAD degree and distribution (degree: none (no stenosis >20%), non-obstructive (at least one stenosis >20%, but no stenosis >=70%), obstructive (any stenosis >=70% or left main (LM) stenosis >=50%); distribution: 1, 2, or 3 vessel).
Main Outcomes and Measures: One-year MI, all-cause mortality, and combined outcomes
Results: Among 37,674 patients, 9,599 patients (25.5%) had non-obstructive CAD, distributed in 1-vessel (n=5,202; 13.8%, of total patients3,022; 8%), 2-vessel (n=1,3753,022; 3.68.0%), and 3-vessel (n=13758,534; 22.73.6%). 19,684 (52.2%) patients had obstructive CAD, distributed in 1-vessel (n=8,534; 22.7% of total patients), 2-vessel (n=5,183; 13.8%), and 3-vessel/LM (n=5,967; 15.8%). Among patients with normal coronary arteries, the estimated 1-year MI rate was 0.1% (95% CI 0.0%, 0.2%); 1-vessel non-obstructive CAD, 0.3% (95% CI 0.2%, 0.5%); 2-vessel non-obstructive CAD, 0.4% (95% CI 0.2%, 0.8%); 3-vessel non-obstructive CAD, 0.7% (95% CI 0.3%, 1.3%); 1-vessel obstructive CAD, 1.0% (95% CI 0.8%, 1.2%); 2-vessel obstructive CAD, 1.9% (95% CI 1.5%, 2.3%); 3-vessel/LM obstructive CAD, 2.2% (95% CI 1.8%, 2.6%). After adjustment, 1-year MI rates progressively increased with increasing CAD extent. Relative to patients without CAD, patients with 1-vessel non-obstructive CAD had a HR of 2.87 (95% CI 1.22, 6.77) for 1-year MI; 2-vessel non-obstructive HR 4.46 (1.99, 10.01); 3-vessel non-obstructive HR 4.93 (1.91, 12.76); 1-vessel obstructive HR 9.18 (4.31, 19.57); 2-vessel obstructive HR 17.29 (8.40, 35.57); and 3-vessel/LM obstructive HR 19.99 (10.21, 39.13). Similar associations were seen among 1-year all-cause mortality and combined outcomes.
indications between October 2007 and September 2012 in the VA health care system.
Conclusions and Relevance: Non-obstructive CAD is associated with significantly greater 1-year MI and all-cause mortality rates relative to patients with no CAD. Patient risk progressively increases by CAD extent, rather than abruptly increasing between non-obstructive and obstructive CAD.
These results are consistent with the emerging biologic understanding of coronary atherosclerosis and suggest that a concept of a risk gradient should supplant the traditional dichotomous characterization of angiographically-defined CAD.
These findings suggest clinical importance of non-obstructive CAD and warrant call for recognition of the risks inherent in non-obstructive CAD and additional research into therapies interventions to improve outcomes among these patients. This is particular germane for veterans, many of whom have non-obstructive CAD.
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