Technical and clinical success rates of PCIs for CTOs increase over time

Practice makes perfect and, for at least one expert interventional cardiologist, the old adage holds true for technical and clinical success rates of PCIs of chronic total occlusions (CTOs).

A study tracking the improvement over a decade could serve as a model for what to expert from other CTO operators as they gain more experience. Lead researcher Alfredo R. Galassi, MD, of the University of Catania in Italy, and colleagues published their results online in the Journal of the American College of Cardiology: Cardiovascular Interventions on April 13.

The researchers evaluated PCIs of CTOs that Galassi performed from January 2005 to December 2014. During that time period, Galassi performed 1,073 CTO procedures in 1,019 patients.

The researchers divided the patients into two groups: those who underwent the procedure from January 2005 to December 2009 and those who underwent the procedure from January 2010 to December 2014.

They defined coronary CTOs as angiographic evidence of total occlusions with Thrombolysis In Myocardial Infarction flow grade 0 and estimated durations of at least three months. They defined technical success as angiographic success and clinical success as angiographic success with no in-hospital major adverse cardiac events or contrast-induced nephropathy.

Examples of major adverse cardiac events included cardiac death, Q-wave and non–Q-wave MI, tamponade and recurrent symptoms requiring urgent repeat target vessel revascularization with PCI or CABG.

They also used the Japanese Multicenter CTO registry (J-CTO) score to classify the attempted CTO lesions based on their complexity. A score of 0 was considered easy, a score of 1 was considered intermediate, a score of 2 was considered difficult and a score of 3 or greater was considered very difficult.

The mean age of patients was 61.1 years old, and 91.3 percent were men.

The first five-year period (2005 to 2009) included 378 patients and 411 CTO PCI procedures, while the second five-year period (2010 to 2014) included 641 patients and 662 CTO PCI procedures.

During the second five-year period, patients were less likely to smoke and have renal dysfunction, prior revascularization and multivessel coronary artery disease. However, the lesions attempted in the second five-year period were more often visibly calcified and torturous and longer than lesions attempted from 2005 to 2009. The researchers said 29.4 percent of lesions in the first period and 56.6 percent of lesions in the second period were classified as very difficult.

Still, technical success rates increased from 87.8 percent to 94.4 percent and clinical success rates increased from 77.6 percent to 89.9 percent. There were also significant declines in in-hospital major adverse cardiovascular events (2.6 percent vs. 5.8 percent) and contrast-induced nephropathy (2.6 percent vs. 10.9 percent). There were no differences in procedural time, fluoroscopy time and contrast load during the two time periods.

Galassi performed a retrograde approach in 27.2 percent of CTO procedures. The technical success rate of retrograde CTO attempts was 75 percent, while the clinical success rate was 68.4 percent. The retrograde approach was more often successful when used as a first-line strategy than after a failed antegrade approach.

The researchers added that very difficult lesions were significantly associated with longer procedural time, longer fluoroscopy time and greater use of contrast.

“With expertise, a CTO-dedicated operator learns to persist using a methodical approach until a successful outcome is achieved, of course always considering the limitations of dose radiation and contrast,” they wrote. “In fact, the higher the J-CTO score, the greater the use of antegrade dissection re-entry techniques and retrograde approaches in order to overcome anatomic difficulties. This suggests that for lesions with high J-CTO scores, early change of crossing strategy should be considered to avoid unnecessary delays predisposing to failure and complications.”

The study had a few limitations, according to the researchers, including that it had a retrospective design and only included one CTO operator. They also simplified the scoring system, may have underestimated non-Q-wave MI and contrast-induced nephropathy and did not report data regarding radiation exposure and did not account for new techniques and CTO-specific medical technology devices.

“Despite its correlation with lesion complexity, the utility of the J-CTO score in predicting technical success was demonstrated to be limited,” they wrote. “The established prediction model including age, ostial location, and collateral filling was strongly associated with technical failure. 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.”