Background: Increases in carotid intimal medial thickness (IMT), as measured by noninvasive ultrasonography, have been associated with increased risk of myocardial infarction and stroke, particularly in adults 65 years of age or older. We investigated the value of age-normalized carotid IMT measurements in predicting major adverse cardiovascular events in a population of patients referred for carotid IMT measurement.
Methods: Since 1995, 727 patients had carotid IMT measured at the University of Virginia's Preventive Cardiology practice. We successfully contacted 706 of these patients to determine clinical outcomes; 21 patients were lost to follow-up. The 706 patients were entered into a database, age-specific quartiles of carotid thickness developed, and odds ratios were calculated with logistic regression.
Results: Over a mean follow-up period of 4.78 years (range, 2.0-9.3 years), 20 patients had major adverse cardiovascular events: seven patients had myocardial infarctions; seven required revascularization; and six had a stroke or transient ischemic attack. The incidence of events directly correlated with age-normalized measurements of carotid bulb and internal carotid IMT. The highest quartile of carotid bulb IMT demonstrated an odds ratio for all events of 5.8 (95% confidence interval, 1.3-26.6; P = 0.023) when compared to the quartile with the lowest thickness (P = 0.007 for trend). A similar trend for quartiles of internal carotid IMT was also observed (P = 0.03). Common carotid IMT did not significantly predict events.
Conclusions: Age-normalized measurement of carotid bulb and internal carotid IMT may be helpful in determining which individuals would most benefit from aggressive risk-factor modification.