title: Nonobstructive coronary artery disease and risk of myocardial infarction.
abstract: OBJECTIVE
  Little is known about cardiac adverse events among patients with nonobstructive coronary artery disease (CAD).
  
  
  OBJECTIVE
  To compare myocardial infarction (MI) and mortality rates between patients with nonobstructive CAD, obstructive CAD, and no apparent CAD in a national cohort.
  
  
  METHODS
  Retrospective cohort study of all US veterans undergoing elective coronary angiography for CAD between October 2007 and September 2012 in the Veterans Affairs health care system. Patients with prior CAD events were excluded.
  
  
  METHODS
  Angiographic CAD extent, defined by degree (no apparent CAD: no stenosis >20%; nonobstructive CAD: ≥1 stenosis ≥20% but no stenosis ≥70%; obstructive CAD: any stenosis ≥70% or left main [LM] stenosis ≥50%) and distribution (1, 2, or 3 vessel).
  
  
  METHODS
  The primary outcome was 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.
  
  
  RESULTS
  Among 37,674 patients, 8384 patients (22.3%) had nonobstructive CAD and 20,899 patients (55.4%) had obstructive CAD. Within 1 year, 845 patients died and 385 were rehospitalized for MI. Among patients with no apparent CAD, the 1-year MI rate was 0.11% (n = 8, 95% CI, 0.10%-0.20%) and increased progressively by 1-vessel nonobstructive CAD, 0.24% (n = 10, 95% CI, 0.10%-0.40%); 2-vessel nonobstructive CAD, 0.56% (n = 13, 95% CI, 0.30%-1.00%); 3-vessel nonobstructive CAD, 0.59% (n = 6, 95% CI, 0.30%-1.30%); 1-vessel obstructive CAD, 1.18% (n = 101, 95% CI, 1.00%-1.40%); 2-vessel obstructive CAD, 2.18% (n = 110, 95% CI, 1.80%-2.60%); and 3-vessel or LM obstructive CAD, 2.47% (n = 137, 95% CI, 2.10%-2.90%). After adjustment, 1-year MI rates increased with increasing CAD extent. Relative to patients with no apparent CAD, patients with 1-vessel nonobstructive CAD had a hazard ratio (HR) for 1-year MI of 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, 4.2-19.0); 2-vessel obstructive HR, 16.5 (95% CI, 8.1-33.7); and 3-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 3-vessel or LM obstructive CAD. After risk adjustment, there was no significant association between 1- or 2-vessel nonobstructive CAD and mortality, but there were significant associations with mortality for 3-vessel nonobstructive CAD (HR, 1.6; 95% CI, 1.1-2.5), 1-vessel obstructive CAD (HR, 1.9; 95% CI, 1.4-2.6), 2-vessel obstructive CAD (HR, 2.8; 95% CI, 2.1-3.7), and 3-vessel or LM obstructive CAD (HR, 3.4; 95% CI, 2.6-4.4). Similar associations were noted with the combined outcome.
  
  
  CONCLUSIONS
  In this cohort of patients undergoing elective coronary angiography, nonobstructive CAD, compared with no apparent CAD, was associated with a significantly greater 1-year risk of MI and all-cause mortality. These findings suggest clinical importance of nonobstructive CAD and warrant further investigation of interventions to improve outcomes among these patients.
authors.affiliation: VA Eastern Colorado Health Care System, Denver2University of Colorado School of Medicine, Aurora.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Maddox
authors.affiliation: VA Eastern Colorado Health Care System, Denver.
authors.forename: Maggie A
authors.initials: MA
authors.lastname: Stanislawski
authors.affiliation: VA Eastern Colorado Health Care System, Denver2University of Colorado School of Medicine, Aurora3Colorado School of Public Health, Aurora.
authors.forename: Gary K
authors.initials: GK
authors.lastname: Grunwald
authors.affiliation: VA Eastern Colorado Health Care System, Denver2University of Colorado School of Medicine, Aurora.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Bradley
authors.affiliation: VA Eastern Colorado Health Care System, Denver2University of Colorado School of Medicine, Aurora.
authors.forename: P Michael
authors.initials: PM
authors.lastname: Ho
authors.affiliation: Kaiser Permanente Colorado, Denver.
authors.forename: Thomas T
authors.initials: TT
authors.lastname: Tsai
authors.affiliation: Duke University, Durham, North Carolina.
authors.forename: Manesh R
authors.initials: MR
authors.lastname: Patel
authors.affiliation: University of Colorado School of Medicine, Aurora.
authors.forename: Amneet
authors.initials: A
authors.lastname: Sandhu
authors.affiliation: University of Colorado School of Medicine, Aurora.
authors.forename: Javier
authors.initials: J
authors.lastname: Valle
authors.affiliation: Colorado School of Public Health, Aurora4Kaiser Permanente Colorado, Denver6Institute for Health Research, Kaiser Permanente Colorado, Denver.
authors.forename: David J
authors.initials: DJ
authors.lastname: Magid
authors.affiliation: University of Colorado School of Medicine, Aurora.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Leon
authors.affiliation: Brigham and Women's Hospital Heart and Vascular Center, Boston, Massachusetts8Harvard Medical School, Boston, Massachusetts.
authors.forename: Deepak L
authors.initials: DL
authors.lastname: Bhatt
authors.affiliation: Office of Analytics and Business Intelligence, Department of Veterans Affairs, Washington, DC.
authors.forename: Stephan D
authors.initials: SD
authors.lastname: Fihn
authors.affiliation: VA Eastern Colorado Health Care System, Denver2University of Colorado School of Medicine, Aurora.
authors.forename: John S
authors.initials: JS
authors.lastname: Rumsfeld
mesh_terms: D000368:Aged; D001157:Arterial Occlusive Diseases / Q000150:complications*; D015331:Cohort Studies; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000150:complications*; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000401:mortality; D010359:Patient Readmission / Q000706:statistics & numerical data; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors