['NT-probrain natriuretic peptide (NT-proBNP) has been associated with left ventricular (LV) dysfunction and adverse outcome in patients with non-ST-elevation acute coronary syndromes (NSTEACS). However, the underlying pathophysiological mechanisms responsible for this association have not been well established. We sought to explore the relation between NT-proBNP levels and extension of coronary artery disease (CAD) and the presence of more complex and severe coronary lesions.', 'This prospective, multicenter angiographic substudy included 585 patients admitted with NSTEACS. Blinded measurements of NT-proBNP and troponin T were performed at a median time of 3 hours after admission and analyzed centrally. Angiograms were read at a core laboratory by 2 independent readers blinded to patient data. Complex coronary lesion was defined as the presence of at least one of the following: thrombus (+), TIMI flow < 2, or ulcerated plaque.', 'NT-probrain natriuretic peptide levels increased proportionally as LV function decreased. The levels of NT-proBNP were directly related to the extent of the CAD. This association was maintained when we analyzed patients with normal LV function (n = 257). Patients with complex coronary lesions or those with at least one of its individual component had higher levels of NT-proBNP compared with those without complex coronary lesions. After adjusting for clinical and electrocardiographic variables and other biomarkers, positive troponin (OR 2.20, 95% CI 1.50-3.22, P < .0001) and supramedian NT-proBNP levels (OR 1.72, 95% CI 1.19-2.47, P = .003) independently contributed to the prediction of complex coronary lesions.'] Does nT-probrain natriuretic peptide predict complexity and severity of the coronary lesions in patients with non-ST-elevation acute coronary syndromes?