64-slice CT can evaluate drug-eluting stent patency, but high BMI complicates visualization
Koki Nakamura of the department of cardiovascular science and medicine at the Chiba University Graduate School of Medicine in Chiba, Japan, and the colleagues from that institution and Awa Medical Association Hospital in Tateyama, Japan, presented the study, “Influence of Body Mass Index and Stent Size on Whether the Patency of Drug Eluting and Bare Metal Stents can be evaluated in Coronary Arteries by 64-slice CT.”
The researchers said the purpose of the study was to evaluate the influence of BMI and stent size on whether it is possible to evaluate the patency of DES and bare-metal stents (BMS) in coronary arteries using 64-multislice CT with regard to age, sex, heart rate, BMI, diabetes mellitus, stent size and the type of stent (DES or BMS).
Nakamura and his colleagues examined 49 consecutive subjects with 78 stents. Of those stents, 17 were DES, 61 were BMS. The stents were separated into three categories based on implantation site: 34 in the left anterior descending coronary artery (LAD), 13 in the left circumflex coronary artery (LCx) and 31 in the right coronary artery (RCA) underwent enhanced ECG-gated MDCT (using a Light Speed VCT) and coronary arteriography (CAG).
The logistic models were made in each category to predict the impossibility for evaluating patency of stents by CT considering age, sex, BMI, heart rate, BMI, diabetes mellitus, stent size (diameter: 4,3.5, 3, 2.75, 2.5mm) and the type of stent (DES or BMS).
BMI was classified as: greater than 22, 22-25, 25-30 and greater than 30.
Using CT, the percentage of unconfirmed patency was 35 percent DES (17, 25, and 57 percent with 3.5, 3, and 2.5mm diameter, respectively) and 23 percent BMS (33, 21, 19, 0 and 43 percent with 4, 3.5, 3, 2.752.5mm diameter, respectively), respectively. The logistic models significant predictors of impossibility for evaluating stent patency by CT were, by category: BMI (positive predictor) and stent size (negative predictor) relative risks, 1.51 and 0.059, respectively) and BMI (positive predictor) and stent size (negative predictor), respectively.
The type of stent was not a significant predictor in any category. Analysis of evaluable stents by CT only revealed no significant predictor of agreement of findings between CT and CAG. The percentage of impossibility of evaluating stent patency by CT in each BMI category was 0, 16, 17, and 43 percent, respectively. The percentage of impossibility of evaluating stent patency was significantly lower in subjects with BMI lower than 22kg/m2 than in those with BMI greater than or equal to 30kg/m2.
The researchers concluded that the 64-slice MDCT is a non-invasive diagnostic modality with potential for evaluating DES patency with a low incidence of restenosis. However, BMI is a positive predictor and stent size is a negative predictor of an inability to evaluate patency of stents. Therefore, when BMI is high, especially greater than 30 kg/m2, or stent size is small, especially smaller than 3mm diameter, it will be difficult to accurately evaluate stent patency, regardless of whether DES or BMS is used.