CHICAGO — Cardiologists have become more willing to tackle chronic total occlusions in recent years, but their procedural success rate remains “very modest”—and essentially unchanged since the early 1990s, Dr. Ryan D. Christofferson said at the annual meeting of the Society for Cardiovascular Angiography and Interventions.
He presented a retrospective analysis of the Cleveland Clinic Foundation's prospectively acquired interventional cardiology database for 1992-2005. This study showed that the number of percutaneous coronary interventions (PCIs) performed for chronic total occlusions (CTOs) at the clinic began rising in about 2000, with access to improved operator techniques and better guidewires and other devices. But the overall procedural success rate during 1992-2005 was just 56% in the 1,003 patients who underwent 1,062 PCIs for chronic total occlusion in a native coronary vessel, with no significant year-by-year differences.
“We do report a very modest procedural success rate, which hasn't particularly changed over time. This may reflect … increasing attempts at more difficult lesions over time,” said Dr. Christofferson of the clinic.
The analysis makes it clear that there is no downside in attempting to open a CTO in the catheterization lab and there is much to be gained if the effort is successful.
Indeed, successful opening of a chronic total occlusion by PCI independently predicted improved 5-year survival in a Cox multivariate regression analysis, which conferred an adjusted 44% mortality reduction compared with the death rate in patients who underwent an unsuccessful attempt. Overall mortality in the study population was 9.4% at an average follow-up of 39 months; however, there was an absolute 7.2% increase in 5-year survival in patients with successful PCI, compared with patients in whom PCI failed to open the blockage.
Other studies have provided considerable evidence that successful treatment of CTO in patients with viable myocardium also improves other outcomes: angina, left ventricular function, need for coronary artery bypass surgery, and risk of MI.
Adverse events in the Cleveland series comprised a 4% incidence of periprocedural acute MI and a 0.7% rate of coronary perforation; most cases were asymptomatic. There were no periprocedural deaths or strokes, and 30-day mortality was 0.6%.
“The safety profile is similar to that of traditional non-CTO PCIs at the Cleveland Clinic, so the procedure doesn't appear to be associated with any increased harm to the patients in our experience,” Dr. Christofferson added.
Blockages in the right coronary artery accounted for 40% of the PCIs attempted. The remainder of cases were divided equally between the left anterior descending and left circumflex arteries.
There was no significant difference in procedural success rates on the basis of an individual operator's volume of CTO PCIs. “This is consistent with my hypothesis that people take on what lesions they're able to handle. Those who are less experienced will not attempt more difficult lesions,” said Dr. Christofferson.
CTO of a native coronary artery is frequently encountered at diagnostic angiography. Roughly one-quarter of patients with angiographically significant coronary artery disease have a CTO. Historically, cardiologists have been reluctant to take on these lesions because of the difficulty in opening them and the high restenosis rate, so patients were often referred for cardiac bypass surgery or left to the mercy of their collateral circulation, he said.
The 'very modest procedural success rate' may reflect 'increasing attempts at more difficult lesions over time.' DR. CHRISTOFFERSON