Prediction of cardiovascular morbidity and mortality: comparison of the internal carotid artery resistive index with the common carotid artery intima-media thickness.
OBJECTIVE
The intima-media thickness (IMT) of the common carotid artery (CCA) is well correlated with the degree of arteriosclerosis and is a predictor of cardiovascular morbidity and mortality. The (hemodynamic) resistive index (RI) of the internal carotid artery (ICA) correlates with the degree of arteriosclerosis just as well as IMT. The aim of the study was to compare the predictive values of RI and IMT with regard to cardiovascular morbidity and mortality.


METHODS
A total of 146 patients with cardiovascular risk factors or established arteriosclerosis were included. Duplex sonography of the CCA and ICA was performed, and the IMT and RI were measured in both vessels. During follow-up for a median of 36 months, the occurrence of cardiovascular events (myocardial infarction, stroke, or cardiovascular death) was assessed.


RESULTS
Thirty-nine cardiovascular events occurred in 28 patients (19.2%). The relative risk for a cardiovascular event per increase of the IMT by 1 SD (0.16 mm) was 1.53 (95% CI, 1.07 to 2.18) and 1.91 (95% CI, 1.34 to 2.73) for RI ICA (0.08). The event rate in patients with IMT <0.79 mm (mean) and RI ICA <0.66 (mean) was 11.8% and 12.7% compared with 25.6% (P=0.03) and 25.0% (P=0.06) in patients with IMT > or =0.79 mm and RI ICA > or =0.66, respectively. Log rank analysis showed a continuous increase in the risk of cardiovascular event with increasing range of the IMT (P=0.029) and RI ICA (P<0.001).


CONCLUSIONS
The RI ICA is a predictor of cardiovascular mortality and morbidity, at least comparable to the well-established IMT.
Staub
Daniel
D
Department of Internal Medicine, Cantonal Hospital, Frauenfeld, Switzerland.
Meyerhans
Alessandro
A
Bundi
Beat
B
Schmid
Hans Peter
HP
Frauchiger
Beat
B
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001161:Arteriosclerosis; D002318:Cardiovascular Diseases / Q000175:diagnosis / Q000401:mortality* / Q000473:pathology*; D002339:Carotid Arteries / Q000473:pathology; D017536:Carotid Artery, Common / Q000473:pathology*; D002343:Carotid Artery, Internal / Q000473:pathology*; D018450:Disease Progression; D018572:Disease-Free Survival; D006439:Hemodynamics; D006801:Humans; D008875:Middle Aged; D009203:Myocardial Infarction; D015588:Observer Variation; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D012044:Regression Analysis; D012306:Risk; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012907:Smoking; D013997:Time Factors; D017539:Tunica Intima / Q000473:pathology*; D017540:Tunica Media / Q000473:pathology*