CHICAGO – Roughly 70% of some 1,200 adult patients with type 1 diabetes screened for coronary artery calcium had a score of zero, about the same prevalence as in the general, U.S. adult population, suggesting the unexpected conclusion that a majority of middle-aged patients with type 1 diabetes do not have an elevated risk for coronary artery disease, in contrast to patients with type 2 diabetes.
Among 1,205 asymptomatic people with type 1 diabetes who underwent coronary artery calcium (CAC) measurement and were followed for an average of about 11 years, 71% had a CAC score of zero at baseline followed by a cardiovascular disease event rate of 5.6 events/1,000 patient years of follow-up, a “very low” event rate that made these patients no more likely to have an event than any adult of similar age and sex in the general U.S. population, Matthew J. Budoff, MD, said at the American Heart Association scientific sessions.
In prior reports, about half of patients with type 2 diabetes had a CAC score of zero, noted Dr. Budoff, professor of medicine and a specialist in cardiac CT imaging and preventive cardiology at the University of California, Los Angeles. In a general adult population that’s about 45 years old roughly three-quarters would have a CAC score of zero, he noted.
Until now, little has been known about CAC scores in asymptomatic, middle-aged adults with type 1 diabetes. The findings reported by Dr. Budoff raise questions about the 2018 revision of the cholesterol guideline from the American College of Cardiology and American Heart Association, released during the meeting (J Am Coll Cardiol. 2018. doi: 10.1016/j.jacc.2018.11.003), which lumps type 1 and type 2 diabetes together as a special high-risk category for cholesterol management.
The guideline should instead “advocate for more therapy with a CAC score of more than 100 and less therapy with a CAC score of zero in patients with type 1 diabetes,” Dr. Budoff suggested. “A statin for someone with a CAC score of zero probably won’t result in event reduction. The 70% of patients with type 1 diabetes who have a CAC score of zero potentially may not benefit from a statin,” he said in a video interview.
Dr. Budoff and his associates used CAC scores and outcomes data collected on 1,205 asymptomatic people with type 1 diabetes enrolled in the EDIC (Epidemiology of Diabetes Interventions and Complications) trial who underwent CAC scoring as part of the study protocol when they averaged 43 years of age. Follow-up tracked the incidence of cardiovascular disease events in 1,156 of these patients for an average of about 11 years. During follow-up, 105 patients had a cardiovascular disease event, an overall rate of 8.5 events/1,000 patient years of follow-up.
The results also confirmed the prognostic power of the CAC score in these patients. Compared with the very low event rate among those with a zero score, patients with a score of 1-100 had 71% more events, patients with a CAC score of 101-300 had a 5.4-fold higher event rate as those with no coronary calcium, and patients with a CAC score of greater than 300 had a 6.9-fold higher event rate than those with no coronary calcium, Dr. Budoff reported.
Coronary calcium deposits, a direct reflection of atheroma load, can change over time, but somewhat slowly. A CAC score of zero is very reliable for predicting a very low rate of cardiovascular disease events over the subsequent 5 years, and in many people it can reliably predict for as long as 10 years, Dr. Budoff said. Beyond that, follow-up CAC scoring is necessary to check for changes in coronary status, “especially in patients with type 1 diabetes,”
SOURCE: Budoff M et al. Abstract 13133.