Revascularization After CTA Confers Mortality Benefit in Stable Patients at High Risk

Revascularization based on results of coronary computed tomographic angiography (CTA) results in a survival advantage at 2 years compared with medical therapy in patients found to have high-grade coronary artery disease (CAD), according to results from a large international registry study published online October 9, 2012, ahead of print in the European Heart Journal. No benefit of revascularization over medical therapy was evident in low-risk patients, however.

James K. Min, MD, of Cedars-Sinai Medical Center (Los Angeles, CA), and colleagues looked at over 15,000 patients enrolled in the CONFIRM registry. The cohort included patients enrolled from 8 sites in 6 countries who had no known CAD and underwent coronary CTA between 2005 and 2009. Patients were then categorized as having high-risk or non-high-risk CAD before undergoing revascularization with PCI, CABG, or both (n = 1,103) or receiving standard medical therapy (n = 14,120).

CTA Better in High-Risk Group

All but 6 patients who underwent revascularization did so within the first 90 days after CTA. Of those treated invasively, 82.8% had PCI, 20.7% had CABG, and 3.5% underwent both procedures.

Over a median follow-up of  2.1 years, the mortality rate was 1.2%, with the majority of deaths occurring in the first year. When deaths were stratified by treatment strategy, 2.2% of patients who underwent revascularization died compared with 1.1% of those who received medical therapy.

Logistic regression analysis showed that the most significant predictors of referral for revascularization were presence of obstructive CAD and pretest probability of CAD. The interaction between these 2 variables also was significant (P = 0.0344).

In patients with high-risk CAD, there was a survival benefit with revascularization that was more apparent with increasing extent of disease, whereas patients with less severe CAD had lower mortality rates with medical therapy alone. In patients with single-vessel CAD, for example, no significant difference in mortality was observed between revascularization and medical therapy. However, a survival benefit for revascularization was seen in those with 2-vessel disease, with a trend towards benefit in 3-vessel disease as well (table 1).

Table 1. Mortality Rates by Vessel Involvement

Multivariable analysis also demonstrated that, compared with medical therapy, revascularization was associated with a survival advantage for patients with high-risk CAD (HR 0.38; 95% CI 0.18-0.83), with no difference in survival for patients who were not at high risk (HR 3.24; 95% CI 0.76-13.89) at the median follow-up period (P for interaction of revascularization and high-risk CAD and time = 0.03).

When subgroups were evaluated to determine whether any particular cohort benefited more from coronary revascularization, improved survival was uniformly seen in the presence of underlying high-risk CAD, with no specific subgroup benefitting substantially more than another.

Left Main Disease, Optimal Medical Therapy Remain Issues

Although the results from the CONFIRM registry appear to be at odds with those of several randomized controlled trials—including COURAGE, which reported no difference at 4.6-year follow-up between patients with angiographic obstructive CAD who were assigned to optimal medical therapy with or without revascularization—the survival benefit observed in high-risk CAD patients may be explained by differences between the study populations, the investigators say.

For example, COURAGE excluded patients with obstructive left main CAD and “may have been affected by unobserved negative selection biases for patients with more high-risk forms of angiographic CAD,” Dr. Min and colleagues write. CONFIRM, on the other hand, assessed outcomes across a broad spectrum of CAD severity with no predefined selection criteria. In addition, since CONFIRM is a registry, “there are no mandated post-test treatments and thus, medical regimens and medical compliance are unknown,” they write.

In a telephone interview with TCTMD, Mauro Moscucci, MD, MBA, of the University of Miami Miller School of Medicine (Miami, FL), said these issues are important to understanding the role of coronary CTA in this population.

“I would be very interested in knowing more about the patients in the CONFIRM registry who were identified as having left main disease and how many of those were treated with revascularization,” he commented. As for the medical therapy, the study does not provide detail about whether patients were on the full regimen of recommended optimal medications.

However, Dr. Moscucci said, the CONFIRM data are important because they demonstrate how well CTA can be used to guide treatment decisions.

“[P]atients who are identified as having high-risk characteristics of CAD by CTA do seem to benefit from revascularization,” he noted. “So, not only is CTA able to identify those at high risk of adverse events, it is able somewhat to triage those patients to treatment that may improve clinical outcomes.”

But according to Dr. Moscucci, much more critical information is needed and will likely come from randomized trials. For instance, it is unclear if one type of procedure—either PCI or CABG—was more effective in these patients, or if revascularization in general was the key to the benefit.

For their part, the study authors say the findings may potentially be useful as “hypothesis-generating data upon which future randomized trials can be considered.”

 

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Source:
Min JK, Berman DS, Dunning A, et al. All-cause mortality benefit of coronary revascularization vs. medical therapy in patients without known coronary artery disease undergoing coronary computed tomographic angiography: Results from CONFIRM (Coronary CT Angiography EvaluatioN For Clinical Outcomes: An InteRnational Multicenter Registry). Eur Heart J. 2012;Epub ahead of print.

 

 

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