乌鸦传媒

A novel -- and simple -- model predicts technical failure of attempts to revascularize chronic total occlusion (CTO), a single-center, single-operator study showed.

Higher scores on the ORA (ostial, Rentrop, age) score, which assigns one point each for age over 75 years and ostial location and two for collateral-filling Rentrop less than 2, were linked to lower rates of technical success in percutaneous coronary intervention (PCI), , of Italy's Cannizzaro Hospital, and colleagues found.

The model's discriminatory power (AUC 0.772) bested that of the existing J-CTO score, which had a limited utility in predicting technical success (AUC 0.556), the researchers reported in JACC: Cardiovascular Interventions

"This model could also be helpful to select appropriate CTO PCI candidates and to answer the question [of] whether a percutaneous revascularization is worthwhile to be attempted," they concluded.

Galassi and colleagues suggested that the ORA score, "being simple and easy to remember," can be used in conjunction with the J-CTO score. Put together, the models can assess both the complexity of a CTO lesion and the risk of technical failure should the operator opt for PCI.

Editorialists , of University of Texas Southwestern Medical Center at Dallas, and , of Minneapolis Heart Institute, noted that other CTO prediction tools -- such as the CL-score and the PROGRESS-CTO score -- already exist.

What's needed is more external validation of all the CTO scores to parse out their strengths and weaknesses, the pair suggested.

"CTO PCI is undergoing a transformative period of growth. Validation and implantation of dedicated scores can help bridge the gap between what can and what is achieved in CTO PCI, providing our patients the successful outcomes they need and deserve," they concluded.

Galassi's retrospective analysis included 1,019 patients who underwent procedures from a single CTO operator between 2005 and 2014. A retrograde approach was applied in 27.2% of the procedures, with more of these occurring toward the end of the study period, particularly after 2012.

Retrograde CTO procedures took more contrast and time than antegrade recanalizations (P<0.01 for both) and had a link with tamponade (3.1% versus 0.6%, P=0.001) as well as in-hospital major adverse cardiovascular events (5.8% versus 2.8%, P<0.001).

Factoring into the success of a retrograde approach were having it as a first-line strategy (OR 3.10, 95% CI 1.53-6.30) and the presence of CC2 collaterals (odds ratio [OR] 3.48, 95% confidence interval [CI] 1.83-6.62). In contrast, increasing age (OR 0.76, 95% CI 0.58-0.98) and disease of the distal segment of the CTO vessel (OR 0.49, 95% CI 0.25-0.96) did not bode well for retrograde success.

Patients who had their recanalization done from 2010 to 2014 had more complex lesions than those in the preceding 5-year period -- but better technical outcomes (94.4% versus 87.8%, P=0.001) and clinical success (89.9% versus 77.6%, P<0.001) from their interventions.

Additionally, while contrast loads and fluoroscopy times remained unchanged between the two time spans, there was a drop in contrast-induced nephropathy (2.6% for late period versus 10.9% for early period, P<0.001).

Limitations included the study's retrospective nature and reliance on the experience of a single physician, which might impact generalizability.

As to why outcomes might have improved over the years, the authors pointed to better patient selection. Those in the latter period "showed less comorbidities (except diabetes), better left ventricular ejection fraction and lower prevalence of prior revascularization and multi-vessel disease," they noted.

Brilakis and Burke agreed that case selection is key to avoiding technical failure. "This is particularly important for less experienced operators, who could benefit from attempting simpler cases (lower score) early on and either deferring or referring the more complex cases early during their CTO PCI experience," they wrote. "CTO scores may be less useful for highly experienced operators who can achieve high success rates even among the most complex cases."

Ultimately, Brilakis told 乌鸦传媒 that he agreed with the idea that a CTO score can be "useful for predicting the difficulty and success rate of CTO PCI."