CTO Treatment Advances: Physician Education Needed to Spread the Word

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Advanced technologies and improved patient selection have increased the rates of successful percutaneous revascularization of chronic total occlusions (CTOs). The biggest hurdle to offering more patients the option of PCI for CTOs is now more a matter of physician education, rather than of technique or technology.

PCI vs. CABG

Evidence is mounting, albeit from non-randomized studies, that patients who have their CTOs revascularized enjoy a better quality of life and a survival advantage compared with those who receive optimal medical therapy.

The choice of revascularization includes PCI or bypass surgery. In the last several years, interventional cardiologists have refined their catheter-based techniques for opening up CTOs. The most prolific practitioners, those performing up to 100-plus CTO PCIs per year on unselected patients, clock a 91 percent success rate, according to William Lombardi, MD, medical director of the cardiac cath labs at St. Joseph Hospital in Bellingham, Wash., and an adjunct clinical assistant professor of cardiovascular medicine at Stanford University in California. Vendors also have responded by designing CTO-specific guidewires and catheters that deliver better torquability and penetration power. Yet, one of the biggest predictors that patients will be referred for bypass surgery is if they have a CTO, says Lombardi.

Why aren’t more patients with CTOs being referred for PCI? The problem, says Lombardi, is multi-factorial. First, there are too few interventionalists with the experience to tackle all levels of CTO complexity. While a handful of U.S. interventionalists perform more than 100 CTO PCIs annually, many interventionalists average only 10 to 15 cases per year—and many of these cases are Level 1, or “simple,” lesions. “If you work only on easy cases, you won’t improve because only 15 percent of all CTOs are Level 1,” says Lombardi. “Our challenge is to educate and proctor physicians, to teach them how to achieve success so they can increase their volume and maintain their technical skills.”

Also, current guidelines do not support performing PCI for CTOs. There is no Class 1 indication for the procedure and the guidelines are not likely to change unless evidence to support the procedure emerges from randomized controlled trials. However, there are no such trials on the horizon because they would be too costly, says Aaron Grantham, MD, an interventional cardiologist at Saint Luke’s Mid-America Heart Institute in Kansas City, and an associate professor of medicine at the University of Missouri-Kansas City School of Medicine. “We have retrospective data from single-center studies that indicate percutaneous revascularization of CTOs is better than optimal medical therapy,” Grantham says. “I have no problem speaking to these data with my patients, but it is not enough for those who make recommendations about appropriateness and indications,” Grantham adds.

The only patients with CTOs in whom it is deemed appropriate to perform angioplasty are those who have symptoms despite maximum medical therapy. There are emerging data, however, from non-CTO patients, including from the COURAGE trial, that indicate ischemic burden is predictive of mortality and that PCI is better than medical therapy alone at relieving ischemia. The evidence also suggests that when the ischemic burden has been reduced by at least 5 percent, survival is better compared with no reduction, Grantham says.

A third confounding factor to the slow adoption of employing PCI for CTOs in the U.S. is reimbursement, which doesn’t equate to the time and effort involved. These complex procedures can last up to six hours, involve multiple stents and multiple wires and utilize much more contrast material and radiation than a non-CTO PCI. In 2006, Kirk Garratt, MD, from Lenox Hill Heart and Vascular Institute in New York City, testified before a CMS committee about the difficulty of CTO PCI and the inadequacy of reimbursement. The initiative was tabled. “There was no appetite for increasing reimbursement in 2006 and it’s even worse now,” Grantham says.

A new era of CTO PCI

In a recent editorial, Craig A. Thompson, MD, from Yale University School of Medicine in New Haven, Conn., wrote that CTOs are not benign entities. He takes issue with the term “stable” coronary disease, “a definition crudely derived from patient symptomatic status” (J Am Coll Cardiol Intv 2010;3;152-154). Data suggest that coronary disease is “not intrinsically stable but rather represents a risk continuum.” Thompson called for a new model to triage patients for CTO PCI based on “ischemic risk assessment, symptomatic status and attributable impairment of left ventricular function” (see graph).

Under this model, unstable coronary disease results in the same general rate of adverse events, no matter the vessel or the ischemic risk. Adverse events for stable coronary disease, however, increase depending on the vessel and the ischemic risk. Occlusions in the left circumflex and right coronary arteries carry less ischemic risk than in the left anterior descending artery and in multivessel disease.

Low-risk patients would not necessarily need to be revascularized compared with high-risk patients with ischemic burden. This model, Thompson wrote, is “strongly supported by the COURAGE trial’s nuclear substudy (Circulation 2008;117:1283–91). In that substudy, follow-up SPECT imaging showed 33 percent of patients in the PCI/optimal medical therapy arm had a 5 percent or more reduction in ischemia compared with 19 percent of patients in the arm receiving only optimal medical therapy. With patients who had reduced ischemia, nearly 80 percent of patients of both groups were angina free. However, in patients who began the study with high-risk ischemia (those with more than 10 percent of their myocardium compromised), treatment with PCI and optimal medical therapy was more commonly effective in reducing ischemia than medical therapy alone.

Thompson wrote that it is likely the “magnitude of benefit is underestimated, given that the COURAGE trial required coronary angiography before enrollment and therefore might have excluded higher-risk patients.” It also is likely, he said, that “we are dramatically under-revascularizing patients with CTOs in terms of attempted PCI rates in patients with appropriate indications.”

To remedy the situation, he recommended better patient selection and outlined two groups to be considered for PCI:
  • Patients with symptoms or attributable left ventricular impairment in whom the risk-benefit estimate justifies the procedure; and
  • Patients (young or young elderly) with an otherwise long life expectancy, irrespective of symptomatic status with multivessel disease, left anterior descending coronary artery CTO and non-left anterior descending coronary artery CTO with large ischemic burden.

Regarding physician experience, Thompson suggested using a multi-tiered system where less experienced interventionalists handle Level 1 lesions, while the more complex lesions should be referred to a dedicated CTO specialist.

“The new era of CTO revascularization in patients with symptoms and/or ischemic burden begins in which the question is not ‘Why should we open the occluded vessel?’ but rather ‘What is the justification to leave the vessel closed?’” Thompson concluded.