Given the task definition and input, reply with output. Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

We sought to determine whether outcomes of chronic total occlusion (CTO) percutaneous coronary intervention (PCI) vary according to CTO target vessel: left anterior descending artery (LAD), left circumflex artery (LCX), and right coronary artery (RCA).', 'We evaluated the clinical and angiographic characteristics and procedural outcomes of 636 patients who underwent CTO PCI at 6 high-volume centres in the United States between January 2012 and March 2014.', 'The CTO target vessel was the RCA in 387 cases (61%), LAD in 132 (21%), and LCX in 117 (18%). LCX lesions were more tortuous and RCA lesions had greater occlusion length and Japanese Chronic Total Occlusion (J-CTO) score, but were less likely to have a side branch at the proximal cap and had more developed collateral circulation. The rate of procedural success was lower in LCX CTOs (84.6%), followed by RCA (91.7%), and LAD (94.7%) CTOs (P = 0.016). Major complications tended to occur more frequently in LCX PCI (4.3% vs 1.0% for RCA vs 2.3% for LAD; P = 0.07). LCX and RCA CTO PCI required longer fluoroscopy times (45 [interquartile range (IQR), 30-74] minutes vs 45 [IQR, 21-69] minutes for RCA vs 34 [IQR, 20-60] minutes for LAD; P = 0.018) and LCX CTOs required more contrast administration (280 [IQR, 210-370] mL vs 250 [IQR, 184-350] mL for RCA and 280 [IQR, 200-400] mL for LAD).
Is percutaneous intervention of circumflex chronic total occlusions associated with worse procedural outcomes : insights from a Multicentre US Registry?