Noninvasive detection of increased carotid artery temperature in patients with coronary artery disease predicts major cardiovascular events at one year: Results from a prospective multicenter study.

BACKGROUND AND AIMS: Limited prospective data have been reported regarding the impact of carotid inflammation on cardiovascular events in patients with coronary artery disease (CAD). Microwave radiometry (MWR) is a noninvasive, simple method that has been used for evaluation of carotid artery temperature which, when increased, predicts 'inflamed' plaques with vulnerable characteristics. We prospectively tested the hypothesis that increased carotid artery temperature predicts future cerebro- and cardiovascular events in patients with CAD. METHODS: Consecutive patients from 3 centers, with documented CAD by coronary angiography, were studied. In both carotid arteries, common carotid intima-media thickness and plaque thickness were evaluated by ultrasound. Temperature difference (ΔT), measured by MWR, was considered as the maximal temperature along the carotid artery minus the minimum; ΔT ≥0.90 °C was assigned as high. Major cardiovascular events (MACE, death, stroke, myocardial infarction or revascularization) were recorded during the following year. RESULTS: In total, 250 patients were studied; of them 40 patients (16%) had high ΔT values in both carotid arteries. MACEs occurred in 30% of patients having bilateral high ΔT versus 3.8% in the remaining patients (p<0.001). Bilateral high ΔT was independently associated with increased one-year MACE rate (HR = 6.32, 95% CI 2.42-16.53, p<0.001, by multivariate cox regression hazard model). The addition of ΔT information on a baseline model based on cardiovascular risk factors and extent of CAD significantly increased the prognostic value of the model (c-statistic increase 0.744 to 0.845, pdif = 0.05) CONCLUSIONS: Carotid inflammation, detected by MWR, has an incremental prognostic value in patients with documented CAD.

Female gender is independently associated with increased carotid temperatures in patients with coronary artery disease.

BACKGROUND: Limited are the data regarding the sex differences in functional carotid artery characteristics. Microwave Radiometry (MWR) is a new noninvasive method, which measures in vivo instantly the internal temperatures of tissues, reflecting inflammation. The aim of the present study was to investigate whether in patients with coronary artery disease (CAD), gender related differences apply in carotid plaque functional characteristics, as assessed by MWR. METHODS: Consecutive patients with significant CAD were included in the study. All patients underwent evaluation of both carotid arteries by 1) ultrasound and 2) MWR. During ultrasound common carotid IMT and plaque thickness were assessed according to Mannheim consensus. During MWR measurements, temperature difference (ΔT) was assigned as maximal temperature along the carotid artery minus minimum. ΔT ≥0.90°C was assigned as high ΔT. RESULTS: In total 364 patients with significant CAD were included in the study. Of these 54 were female and 310 were male. Max plaque thickness and ccIMT were similar between males and females (2.38±1.16 vs. 2.46±1.12mm, p=0.63 and 0.944±0.172 vs. 0.942±0.169mm, p=0.96). Carotid arteries of females showed higher ΔT values (1.16±0.48 vs 0.87±0.45°C, p<0.001). Interestingly, females had more commonly high ΔT values bilaterally (35.2% vs 15.5%, p=0.001). In multivariate analysis, female sex was independently associated with bilateral high ΔT, when adjusted to potential covariates (OR=2.78, 95% CI=1.42-5.45, p=0.003). CONCLUSIONS: In patients with CAD, sex specific differences apply in functional but not in structural carotid artery characteristics. Whether this discrepancy has prognostic significance, remains to be clarified in future studies.