Data from the PROSPECT (Providing regional observations to study predictors of events in the coronary tree) study have shown approximately 20% of patients with acute coronary syndrome successfully treated with stents and contemporary medical treatment developed major adverse cardiac events within three years. The study was led by Gregg W Stone, New York-Presbyterian Hospital and Columbia University Medical Center, USA.
Between 2004 and 2006, 697 patients with acute coronary syndromes were enrolled at 37 sites in the United States and Europe after undergoing successful percutaneous coronary intervention. Median age was 58.1 years, 24% were women, 17.1% had diabetes mellitus and 45.8% had hypertension. Median follow-up was 3.4 years and pre-specified primary endpoint was the incidence of major adverse cardiovascular events.
Residual disease after percutaneous coronary intervention varied depending on the imaging technique used. Angiography identified 1,814 untreated lesions, including 110 with a diameter stenosis of at least 50% and 12 with a diameter stenosis of at least 70%.
Grayscale intravascular ultrasonography found 3,160 lesions in the proximal-to-middle segments of the three major epicardial coronary arteries in 673 patients, including 620 lesions with a minimal luminal area of 4mm2 or less and 283 lesions with a plaque burden of at least 70%. With radiofrequency intravascular ultrasonography, most lesions were classified as pathologic intimal thickening or fibroatheromas with 596 thin-cap fibroatheromas identified in 313 of 623 patients.
Eleven patients (1.6%) had complications attributed to the three-vessel imaging procedure resulting in three (0.4%) non-fatal myocardial infarctions.
During a median follow-up period of 3.4 years, 149 major adverse cardiovascular events occurred in 135 patients (three-year cumulative rate, 20.4%), most of which were rehospitalisations for unstable or progressive angina. Cardiovascular events occurred in 31 patients (three-year cumulative rate, 4.9%) within three years. The three-year cumulative rate of major adverse cardiovascular events of recurrent disease in originally treated culprit lesions was 12.9% (118 lesions in 83 patients). The three-year cumulative event rate related to non-culprit lesions was 11.6% (104 lesions in 74 patients) and the origin of 18 events in 17 patients (2.7%) was indeterminate.
Insulin-requiring diabetes was the strongest patient-level predictor of non-culprit-lesion-related major adverse cardiovascular events at follow-up. Independent predictors of subsequent events were baseline plaque burden of at least 70%, minimal luminal area of 4mm2 or less, and the presence of thin-cap fibroatheromas.
“Patients treated with contemporary medical therapy who develop non-culprit lesion events present most commonly with progressive or unstable angina, and rarely with cardiac death, cardiac arrest or myocardial infarction. The combination of large plaque burden without a visible cap identifies lesions which are at especially high risk for future adverse cardiovascular events”, the study concluded. The results were recently published in The New England Journal of Medicine.