BACKGROUND/RATIONALE:
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.

OBJECTIVE(S):
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.

METHODS:
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

FINDINGS/RESULTS:
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.

IMPACT:
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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External Links for this Project

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PUBLICATIONS:

Journal Articles

1. Hsu JC, Maddox TM, Kennedy K, Katz DF, Marzec LN, Lubitz SA, Gehi AK, Turakhia MP, Marcus GM. Aspirin Instead of Oral Anticoagulant Prescription in Atrial Fibrillation Patients at Risk for Stroke. Journal of the American College of Cardiology. 2016 Jun 28; 67(25):2913-23. [view]
2. Gehi AK, O'Brien E, Pathak RK, Sanders P, Kennedy KF, Virani SS, Masoudi FA, Maddox TM. Implications of the LEGACY trial on US Atrial Fibrillation Patients: An NCDR Research to Practice (R2P) Project. The American journal of cardiology. 2017 Feb 15; 119(4):579-584. [view]

Conference Presentations

1. Maddox TM. VASc Risk Factors on Anticoagulant Prescription in Patients with Arterial Fibrillation: Insights from the NCDR PINNACLE Registry. Paper presented at: Quality of Care and Outcomes Research in Cardiovascular Disease and Stroke Annual Scientific Forum; 2016 Feb 29; Phoenix, AZ. [view]

DRA: Aging, Older Veterans' Health and Care, Cardiovascular Disease
DRE: Epidemiology
Keywords: none
MeSH Terms: none