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Healio
November 05, 2014
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Nonobstructive CAD associated with greater risk for MI, death

In a cohort of veterans undergoing elective coronary angiography, nonobstructive CAD was associated with greater risk for MI and all-cause mortality at 1 year.

Thomas M. Maddox, MD, MSc, FACC, FAHA, and colleagues conducted a retrospective cohort study of all US veterans, excluding those with prior CAD events, who underwent elective coronary angiography in the Veterans Affairs health care system from 2007 to 2012 (n=37,674).

Patients were stratified based on whether they had no apparent CAD (stenosis <20%), nonobstructive CAD (stenosis 20% to 69%, but left main stenosis <50%) or obstructive CAD (any stenosis ≥70% or left main stenosis ≥50%). Patients with nonobstructive CAD or obstructive CAD were further stratified based on whether CAD was present in one, two or three vessels; those with left main obstructive CAD were included in the three-vessel obstructive CAD group.

Thomas M. Maddox, MD, MSc, FACC, FAHA

Thomas M. Maddox

The primary outcome was hospitalization for nonfatal MI within 1 year of the index angiography. Secondary outcomes included 1-year all-cause mortality and combined 1-year MI and mortality.

Overall, 22.3% of patients had nonobstructive CAD and 55.4% had obstructive CAD.

After adjustment for numerous covariates, 1-year MI rates increased with increasing CAD extent. Compared with patients with no apparent CAD, the HRs for MI at 1 year were as follows:

  • Patients with one-vessel nonobstructive CAD: HR=2; 95% CI, 0.8-5.1.
  • Patients with two-vessel nonobstructive CAD: HR=4.6; 95% CI, 2-10.5.
  • Patients with three-vessel nonobstructive CAD: HR=4.5; 95% CI, 1.6-12.5.
  • Patients with one-vessel obstructive CAD: HR=9; 95% CI, 4.2-19.
  • Patients with two-vessel obstructive CAD: HR=16.5; 95% CI, 8.1-33.7.
  • Patients with three-vessel or left main obstructive CAD: HR=19.5; 95% CI, 9.9-38.2.

One-year mortality rates increased with increasing CAD, ranging from 1.38% for patients with no apparent CAD to 4.3% for patients with three-vessel or left main obstructive CAD.

The researchers found no association between one- or two-vessel nonobstructive CAD and increased risk for 1-year mortality, but there was an elevated risk for 1-year mortality in patients with 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 left main obstructive CAD (HR=3.4; 95% CI, 2.6-4.4). They found similar associations for the combined outcome of 1-year MI and mortality.

“These findings suggest clinical importance of nonobstructive CAD and warrant further investigation of interventions to improve outcome among these patients,” Maddox, cardiologist at the Veterans Administration Eastern Colorado Health Care System and associate professor of medicine at the University of Colorado School of Medicine, Aurora, Colo., and colleagues wrote, further noting that the findings are “consistent with prior biologic studies indicating that a majority of MIs are related to nonobstructive stenoses.”

Disclosure: See the full study for a list of the researchers’ relevant financial disclosures.

Sources/Disclosures

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Source: Maddox TM. JAMA. 2014;312:1754-1763.