Predictors of Bad Outcomes After Unprotected Left Main Disease Similar Regardless of Treatment

Certain factors signal a heightened risk of doing poorly among patients with unprotected left main CAD no matter whether they undergo PCI or CABG or are treated with medical therapy alone, a registry study shows.

Chronic renal failure, older age, low ejection fraction, a history of heart failure, and diabetes were strongly associated with MACCE and all-cause mortality across treatment strata in these patients, lead author Se Hun Kang, MD (CHA Bundang Medical Center, Seongnam, South Korea), and colleagues report.

“Our findings will help clinicians assess the risk of [unprotected left main coronary artery (ULMCA)] disease and more aggressively manage patients . . . who would be at higher risk of future events,” the authors write in a study published online July 12, 2017, ahead of print in Circulation: Cardiovascular Interventions.

Davide Capodanno, MD (University of Catania, Italy), who was not involved in the analysis, told TCTMD that this study is important because the large numbers of patients and events provide clarity about the key predictors of long-term outcomes in this subset. He noted, however, that the risk factors identified are largely consistent with prior research.

He agreed with the researchers that the predictors could be used to target higher-risk patients for additional attention, including enhanced follow-up. Regarding renal disease and heart failure in particular, Capodanno said “[targeting] some special preventive measures for these conditions is as important as giving the right treatment for left main disease.”

Although predication scores have been developed both for risk stratification and clinical decision-making for patients with complex CAD with or without unprotected left main disease, few studies have examined whether predictors of poor outcomes differ based on the type of treatment patients receive.

To investigate that question, Kang et al turned to the IRIS-MAIN registry, which recruited patients from 50 centers in China, India, Indonesia, Japan, Malaysia, South Korea, Taiwan, and Thailand. The analysis included 5,795 patients with unprotected left main disease enrolled between 1995 and 2013; 49.2% were treated with PCI, 40.3% with CABG, and 10.5% with medication alone.

There were two primary outcomes—MACCE (death, MI, stroke, or repeat revascularization) and all-cause death—and both occurred at the highest rates through up to 5 years of follow-up (median 4.3 years) among patients receiving medical therapy alone. In the PCI, CABG, and medical therapy groups, MACCE rates were 25.7%, 19.9%, and 42.5%, respectively, and mortality rates were 11.3%, 14.1%, and 32.0%.

MI and strokes rates were lowest in the PCI group and highest in the CABG group, whereas repeat revascularization was most frequent in the PCI group and least common in the CABG group.

A number of factors were associated with MACCE and all-cause death, but a handful were among the strongest regardless of treatment stratum.

In the PCI group, chronic renal failure, older age (65 and older), and prior heart failure were most strongly associated with MACCE, and chronic renal failure, older age, and low ejection fraction (less than 50%) were most strongly tied to death.

The most robust risk factors for MACCE and death in the CABG group were chronic renal failure, older age, and low ejection fraction. In the medication group, they were older age, low ejection fraction, and diabetes.

The findings “suggest that, despite the distinct biological pathways of each risk factor, the prognostic impact of clinically relevant predictors were relatively uniform irrespective of treatment strategy,” the authors write.

What About SYNTAX Scores?

The similarity in risk factors for poor outcomes across treatment modalities contrasts with evidence showing that the SYNTAX and SYNTAX II scores can be helpful in selecting the appropriate approach, Kang et al point out, noting that these scores were not systematically measured in the IRIS-MAIN registry.

They add, however, that the finding is consistent with results of the EXCEL and NOBLE trials, which indicated that “SYNTAX score (CAD extent) is not of major importance.”

Capodanno said it would have been interesting to include a look at the SYNTAX score in this study to evaluate the impact of anatomic complexity in the context of clinical factors when addressing prognostic factors.

He added that the findings are probably not useful for selecting the appropriate treatment for a given patient with unprotected left main disease because of the consistency of risk factors across strata.

“The truth is probably that decision-making should be guided by anatomic complexity and the feasibility of the procedure, and of course the patient should also be part of this decision-making,” Capodanno said.

“For now,” the study authors say, “there might be no clear-cut answer on the optimal revascularization strategy in ULMCA disease.”