Potential Predictive Model Developed for Technical and Clinical Failure in Chronic Total Occlusion

Researchers created a prediction score for technical failure in chronic total occlusion attempts using age ≥75 years (1 point), ostial location (1 point), and collateral filling Rentrop

Success rates for chronic total occlusion (CTO) intervention using percutaneous coronary intervention (PCI) have increased, despite the difficulty of the procedure, according to a study published in JACC: Cardiovascular Interventions.

Researchers sought to establish a predictive model for technical failure by evaluating the experience of a CTO dedicated operator. They enrolled 1019 patients who underwent 1073 CTO procedures, all performed by a single operator. The patients were divided into 2 time period groups: the first from January 2005 to December 2009 (n=378) and the second from January 2010 to December 2014 (n=641).

“Observations were randomly assigned to a derivation set and a validation set (at a 2:1 ratio),” the authors wrote. “A prediction score was established by assigning points for reach independent predictor of technical failure in the derivation set according to the beta coefficient and summing all points accrued.”

Coronary CTOs were defined as “angiographic evidence of total occlusions with Thrombolysis In Myocardial Infarction (TIMI) flow grade 0 and estimated durations of at least 3 months.”

More complex lesions were attempted in the second period compared with those lesions in first period, but both technical and clinical success rates significantly improved (87.8% to 94.4%; P=.001 and 77.6% to 89.9%; P<.001, respectively). These CTO lesions were often more visibly calcified and tortuous, longer, and had been subjected to previous unsuccessful attempts.

Researchers created a prediction score for technical failure using age ≥75 years (1 point), ostial location (1 point), and collateral filling Rentrop <2 (2 points). They named the prediction score “ORA score”—consisting of ostial location, Rentrop <2, and age. Based on these criteria, 4 difficulty groups were established: easy (0), intermediate (1), difficult (2), and very difficult (3-4). The probable success rate for each group was 95.9%, 90.6%, 87.6%, and 57.1%, respectively.

In 27.2% (n=292) of CTO procedures, a retrograde approach was performed vs 79.8% (n=233) performed as a first approach and 20.2% (n=59) after antegrade failure. Retrograde approach was more successful when it was used as a first line strategy than after a failed antegrade approach (78.0% vs 55.9%; P<.001). Nonetheless, retrograde CTO attempts had a technical success rate of 75% and a clinical success rate of 68.4%.

Since 2009, the technical success rate has improved, surpassing 90% and reaching 95.4% in 2014. The clinical success rate has also improved—from 57.7% in 2005 to 92.1% in 2014.

The study authors explained that previous interventionalist reports demonstrated the impact of a CTO operator’s experience and procedure volume on the technical and clinical success rates. “In the current study, a technical success rate superior to 90% had been achieved since the fourth year of experience, and maintained thereafter.”

“Further validation of this score in large cohorts of patients attempted by different CTO operators with different levels of expertise will be required to expand its use in CTO interventions,” they concluded.

In the future, the ORA score might also help clinicians select suitable patients for CTO intervention.


Galassi AR, Bokhris M, Azzarelli S, Castaing M, Marza F, Tomasello SD. Percutaneous coronary revascularization for chronic total occlusions: a novel predictive score of technical failure using advanced technologies. JACC Cardiovasc Interv. 2016. doi:10.1016/j.jcin.2016.01.036.