BACKGROUND Differential diagnosis between ischemic (IDCM) and the nonischemic type (NIDCM) of cardiomyopathy constitutes a challenge in the daily medical practice. Carotid and aortic elastic properties deteriorate in patients with coronary artery disease. However, their predictive role in differentiating IDCM from NIDCM has not been addressed so far. AIM OF THE WORK To examine carotid and aortic mechanical functions using conventional and Doppler tissue echocardiography in the distinction between IDCM and NIDCM in patients with clinically undetermined etiology. METHODS 70 patients with dilatation and diffuse impairment of the left ventricular (LV) contraction were studied. All patients underwent carotid duplex for measuring intima-media (IMT) thickness, peak systolic velocity (PSV), and luminal diameters (LD). Aortic distensibility, strain, and aortic wall velocities (systolic (Sa), early diastolic (Ea), late diastolic (Aa) velocities, Sa(t), and Ea(t)) were measured. According to coronary angiographic results, patients were categorized into IDCM (n = 36) (age 57.9 +/- 9.2 years) and NIDCM groups (n = 34) (age 56.0 +/- 8.3 years); they were compared to 30 age- and sex-matched healthy individuals as a control group. RESULTS The aortic pulsatile change, aortic strain, and distensibility were significantly reduced in both patient groups in comparison to control (P < 0.001). These parameters were much impaired in patients with IDCM compared with NIDCM (P < 0.001). IDCM have more deterioration of Sa, Ea, and Aa compared with NIDCM group (7.6 +/- 2.4 vs. 8.9 +/- 1.58, 7.5 +/- 2.8 vs. 10.6 +/- 1.5, 9.0 +/- 1.4 vs. 6.9 +/- 2.4 cm/sec; P < 0.001), respectively. In IDCM, the variables of aortic elastic properties were correlated only to age, while in NIDCM they were correlated to hemodynamics, LV volumes, wall thickness, and mass. Both carotid diameter and IMT were significantly increased in IDCM in comparison to NIDCM and control (P < 0.001). Carotid distensibility was significantly reduced in IDCM compared with NIDCM and control (P < 0.001). However, the carotid properties strongly correlated to risk factors in IDCM and to hemodynamics and LV function in NIDCM. Using ROC curve, a cutoff value < or =4.7 (cm(2)/dyne/10(3)) for aortic distensibility, value <8 cm/sec for Sa and IMT >0.8 mm predicted IDCM with 94.4%, 72.7%, and 97.2% sensitivity and 88.2%, 85.3%, and 97.1% specificity, respectively. CONCLUSION Both carotid and aortic mechanical functions are more deteriorated in ischemic compared with nonischemic dilated cardiomyopathy. Different functional and structural mechanisms might be responsible for the deterioration of arterial elastic properties in each category.