Lara C. Pullen, PhD

December 06, 2013

CHICAGO — Coronary CT angiography may be a sensible alternative to the cardiac stress test or angiography in patients with mild artery disease, new research hints.

The noninvasive test uses CT to image the amount of plaque in the coronary arteries. "CT is not the test for everyone, but it certainly is an option for those with low to intermediate risk," said Jonathon Leipsic, MD, director of medical imaging at St. Paul's Hospital in Vancouver, British Columbia, Canada.

Dr. Leipsic presented results from a prospective international cohort study here at the Radiological Society of North America 99th Scientific Assembly and Annual Meeting.

Although many people in the audience said they were enthusiastic about using coronary CT angiography as an alternative to a cardiac stress test or angiography, the study was actually designed to determine whether there are sex-based prognostic differences for coronary artery disease.

The primary end point was the occurrence of major adverse cardiac events including death and myocardial infarction.

Data for the study came from the Coronary CT Angiography Evaluation for Clinical Outcomes: An International Multicenter (CONFIRM) Registry. The registry contains results from clinically indicated coronary CT angiographies and data on traditional cardiovascular risk factors.

 
CT is not the test for everyone, but it certainly is an option for those with low to intermediate risk.
 

Of the 27,125 individuals from 12 cluster sites in the registry, 18,158 patients were identified who had no known coronary artery disease and whose coronary CT angiography results were normal or indicated nonobstructive disease (<50% blockage).

From this group, the researchers created a propensity-matched cohort of 11,462 patients.

In the cohort, 164 (1.4%) patients experienced fatal or nonfatal myocardial infarction. Of those, 37 had a myocardial infarction and did not die, 120 died without myocardial infarction, and 7 experienced myocardial infarction and died.

For each patient, the researchers derived a Framingham score, which predicts an individual's risk for cardiovascular disease. They compared the scores with the coronary CT angiography results and actual health outcomes.

The team performed a statistical analysis of the matched cohort and controlled for all cardiovascular risk factors. When patients were matched for age, risk factors, symptoms, and extent of coronary artery disease, rates of incident mortality and myocardial infarction were comparable in men and women.

Table. Relation Between Coronary Artery Disease and Major Adverse Events

End Point Men Women P Value
Nonobstructive Coronary Artery Disease      
   Hazard ratio for major cardiac event 1.83 1.84
   Annualized rate of major cardiac event 0.8% 0.9% .89
No Coronary Artery Disease      
   Annualized rate of major cardiac event 0.3% 0.4% .20

 

The prognosis for major adverse cardiac events was not only the same for men and women, it was not affected by presenting symptoms.

These results contradict findings from the Women's Health Initiative, which indicated that women with nonspecific or atypical chest pain have a 2-fold greater risk for nonfatal myocardial infarction than men.

Many times physicians choose between "a cardiac stress test and an angiography. Coronary CT angiography may be a reasonable alternative," said Candice Johnstone, MD, from Froedtert Hospital in Milwaukee, Wisconsin.

Dr. Leipsic reports financial relationships with General Electric Company, Edwards Lifesciences, and Heartflow. Dr. Johnstone has disclosed no relevant financial disclosures.

Radiological Society of North America (RSNA) 99th Scientific Assembly and Annual Meeting: Abstract SSJ05-05. Presented December 3, 2013.

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