Even Mild Coronary Artery Disease Places Diabetic Patients at Risk for Heart Attacks

According to a new long-term cardiac imaging study, diabetic patients with even mild coronary artery disease (CAD) are faced with the same comparative risk for a heart attack or other major adverse heart events as diabetics with serious single-vessel obstructive disease. Previously, these patients were believed to have a lower risk of major adverse cardiovascular events and death than patients with obstructive CAD.

The study’s findings were presented December 2, 2014, at the annual meeting of the Radiological Society of North America (RSNA), held in Chicago (IL, USA). Researchers from the University of British Columbia and St. Paul’s Hospital (both based in Vancouver BC, Canada) analyzed data from the Coronary CT Angiography Evaluation for Clinical Outcomes: An International Multicenter (CONFIRM) Registry, which was developed to examine the prognostic benefits of cardiac computed tomography angiography (CCTA) for predicting adverse cardiac events related to coronary artery disease. The registry, which has CCTA data on 40,000 patients from 17 centers worldwide, now has five-year follow-up data on 14,000 patients.

“The CONFIRM Registry is the largest long-term data set available and allowed us to evaluate the long-term prognostic value of CCTA in diabetic patients,” said study coauthor Jonathan Leipsic, MD, vice chairman of the department of radiology at the University of British Columbia.

The researchers analyzed data on 1,823 diabetic patients who underwent CCTA to detect and determine the extent of CAD, in which a waxy substance called plaque, accumulates inside the arteries of the heart. This plaque accumulation causes the artery wall to thicken, which limits or, in some instances, completely obstructs blood flow. Men and women (median age 61.7) in the study were categorized as having no coronary artery disease, mild disease (less than 50% of coronary artery narrowed), or obstructive disease (more than 50% artery obstruction). Over a 5.2-year follow-up period, there were 246 deaths, representing 13.5% of the total study group.

Major adverse cardiovascular event (MACE) data was available on 973 patients. During the follow-up period, 295 (30.3%) of the patients experienced a MACE, such as heart attack or a procedure to re-open an obstructed artery called a coronary revascularization.

The researchers discovered that both obstructive and mild, or non-obstructive, coronary artery disease as determined by CCTA were related to patient deaths and MACE. Most importantly, the study found that the comparative risk for death or MACE for a patient with mild coronary artery disease was comparable to that of patients with single vessel obstructive disease.

“Until now, two-year follow-up studies suggested that a diabetic patient with mild or non-obstructive coronary artery disease had a lower risk of major adverse cardiovascular events and death than patients with obstructive disease,” said co-author Philipp Blanke, MD, radiologist at the University of British Columbia and St. Paul’s Hospital. “Our five-year follow-up data suggest that non-obstructive and obstructive coronary artery disease as detected by cardiac CTA in diabetic patients are both associated with higher rates of mortality.”

Dr. Leipsic noted that researchers need a better determination of the evolution of plaque in the arteries and patient response to treatments. “Cardiac CT angiography is helpful for identifying diabetic patients who are at higher risk for heart events, who may benefit from more aggressive therapy to help modify that risk,” added Dr. Leipsic.

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