CAC score predictive of myocardial ischemia risk

WASHINGTON — A coronary artery calcium score of 400 or higher is associated with increased prevalence and risk for ischemia, researchers reported at the American College of Cardiology Scientific Sessions.

However, a score lower than 100 was associated with a relatively low frequency of ischemia and is effective in ruling out ischemia.

Researchers conducted a meta-analysis of 17 studies that evaluated the link between coronary artery calcium (CAC) score and myocardial ischemia. The studies were published between 2000 and 2013, and reported CAC scores assessed by CT or reported myocardial ischemia by single-photon emission CT myocardial perfusion imaging (SPECT MPI).

Rates of ischemia were presented according to CAC scores of 0, 1-100, 101-400 and/or ≥400 in all studies.

Twelve studies compared CAC scores of 0 vs. >0 in a total of 5,150 participants. Sensitivity for ruling out ischemia, as indicated by receiver-operating curve analysis, was high across these studies (0.87; 95% CI, 0.84-0.89), while specificity was low (0.29; 95% CI, 0.27-0.3). Across 13 studies of 6,165 patients in which CAC score thresholds of <400 and ≥400 were compared, specificity for the detection of ischemia was high (0.75; 95% CI, 0.73-0.76) while sensitivity was lower (0.53; 95% CI, 0.49-0.56). CAC scores <100 and ≥100 were compared in 10 studies of 5,289 patients. Researchers calculated a sensitivity of 0.73 (95% CI; 0.69-0.77) and a specificity of 0.52 (95% CI; 0.51-0.54) for ischemia detection using these thresholds.

Ischemia rates across all four evaluated categories (0, 1-100, 101-400 and ≥400) were reported in six studies of 3,040 patients, including both symptomatic and asymptomatic individuals with suspected CAD. Compared with a CAC score of 0, patients with a score ≥400 were at greatest risk for myocardial ischemia (pooled OR=5.08; 95% CI, 2.57-10.05), followed by those with a CAC score of 101 to 400 (pooled OR=3.06; 95% CI, 1.89-4.97) and 1 to 100 (pooled OR=3.06; 95% CI, 1.89-4.97).

Chirag Bavishi

“The current meta-analysis shows that absence of CAC is associated with a relatively low frequency of ischemia, and is effective in ruling out the same,” Chirag Bavishi, MD, MPH, internal medicine resident at Mount Sinai St. Luke's-Roosevelt Hospital Center in New York, said at a press conference. “A CAC score ≥400 is associated with increased prevalence and risk for ischemia. Increasing CAC score showed an incremental risk for myocardial ischemia.”

Bavishi said the researcher team observed heterogeneity in the frequency of ischemia as CAC score increased, and that further evaluation of clinical parameters that may influence the link between CAC score and ischemia should be conducted. – by Adam Taliercio

For more information:

Bavishi C. #1104-63. Presented at: American College of Cardiology Scientific Sessions ; March 29-31, 2014; Washington, D.C.

Disclosure: Bavishi reports no relevant financial disclosures.