From the Journals

SYNTAX analysis: Making the case for CABG over PCI

 

Key clinical point: Physicians should clearly communicate to patients with complex multivessel artery disease the key findings of the SYNTAX trial.

Major finding: The SYNTAX trials showed the risk of cardiac death from myocardial infarction after percutaneous coronary intervention (PCI) is 10 times greater than that after coronary artery bypass grafting in higher-risk patients.

Data source: A post hoc analysis of causes of death in all 3,075 trial and registry patients in the Synergy Between Percutaneous Coronary Intervention With Taxus and Cardiac Surgery (SYNTAX) trial.

Disclosures: Dr. Mack and coauthors reported having no financial disclosures.

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Why PCI deserves more scrutiny

In their invited editorial commentary, Saswata Deb, MD, and Stephen E. Fremes, MD, of the Schulich Heart Center at the University of Toronto, concurred with the conclusions of Dr. Mack and colleagues (J Thorac Cardiovasc Surg. 2016;152:1241-2). And Joseph F. Sabik III, MD, of the Cleveland Clinic arrived at a similar conclusion in an accompanying editorial (J. Thorac Cardiovasc Surg. 2016;152:1227-8).

Dr. Deb and Dr. Fremes found noteworthy the point Dr. Mack and coauthors raised about cardiologists and internists continuing to recommend PCI to patients with complex multivessel CAD despite evidence from SYNTAX and other trials. “This raises the importance of having a multidisciplinary heart team,” Dr. Deb and Dr. Fremes said.

But they also raised an important question about the difference in outcomes between CABG and PCI in complex multivessel disease. CABG should be the preferred intervention if the high rates of late fatal myocardial infarction after PCI are due to incomplete revascularization; however, if late stent thrombosis was the cause of this disparity in outcomes, then improvements in PCI could close that gap.

In his editorial, Dr. Sabik attributed the difference in outcomes between PCI and CABG to the ability of the former to both treat existing and prevent future stenosis. PCI can be “difficult, dangerous, and even impossible” when the target vessel is totally occluded or the stenosis is complex, hence leading to incomplete revascularization and residual ischemia. “Performing CABG to these vessels is no more difficult than for an isolated, noncomplex stenosis,” Dr. Sabik said.

Dr. Sabik disclosed he is the principal investigator for an Abbott Laboratories–sponsored trial of left main coronary disease, and is on the scientific advisory board of Medtronic.

Dr. Deb and Dr. Fremes had no relationships to disclose.


 

FROM THE JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY

Whenever seminal clinical trials report results that challenge conventional thinking, physicians face the challenge of actually applying those findings in the clinic. A team of cardiac surgeons from Baylor University in Plano, Tex., has offered its take on the clinical implications of recent findings from the cause-of-death analysis of the SYNTAX trial that compared coronary artery bypass grafting with stenting: When counseling higher-risk patients with coronary artery disease about revascularization procedures, cardiologists and cardiac surgeons should clearly elucidate the dramatic advantage of coronary artery bypass grafting over stenting that SYNTAX had demonstrated.

Michael Mack, MD, and coauthors made their case in a featured expert opinion in the Journal of Thoracic and Cardiovascular Surgery (2016;152:1237-40).

Dr. Michael J. Mack

Dr. Michael J. Mack

The first results from the Synergy Between Percutaneous Coronary Intervention With Taxus and Cardiology (SYNTAX) trial were reported in 2009 (N Engl J Med. 2009;360:961-72), and demonstrated the benefits of coronary artery bypass grafting (CABG) over percutaneous coronary intervention (PCI). In the latest featured expert opinion, Dr. Mack and coauthors drilled down into a post hoc analysis of causes of death in SYNTAX (J Am Coll Cardiol. 2016;67:42-55). Those results showed a tenfold higher rate of cardiac death due to heart attack in PCI patients vs. those who had CABG. “This was particularly striking in patient with three-vessel disease, high SYNTAX scores, or diabetes,” Dr. Mack and colleagues said.

“In fact, there was a significant survival advantage for CABG in the patients with intermediate and high SYNTAX scores, with the death rate of CABG versus PCI being 9.6% versus 16.3% (P less than .047) and 8.8% versus 17.8% (P less than .02), respectively,” they wrote.

The advantages of surgery “have been most striking for patients with intermediate or high SYNTAX scores, but seem to exist for patients with low scores as well, although requiring more follow-up,” Dr. Mack and colleagues said. But the situation is less clear in other subgroups, particularly in patients with less diffuse distal disease and lower SYNTAX scores, they added.

Complete revascularization after the procedure may explain the better outcomes with CABG, as 43.3% of those in the PCI arm had incomplete revascularization vs. 36.8% in the CABG arm. “Incomplete revascularization was associated with increased risk for major adverse cardiac or cerebrovascular events three years after PCI, but incomplete revascularization in the CABG group could not be identified as a predictor for worse outcomes,” Dr. Mack and colleagues noted.

The expert opinion authors debunk one of the recent criticisms of SYNTAX: that its reliance on first-generation drug-eluting stents is dated and not relevant today. They noted the more recent Bypass Surgery Vs. Everolimus-Eluting Stent Implantation for Multivessel Coronary Artery Disease trial found a similarly higher rate of death, heart attack, and target vessel revascularization occurred more frequently in the PCI group (15.3% vs. 10.6% in the CABG group) (N Engl J Med. 2015;372:1204-12).

Nonetheless, Dr. Mack and coauthors found room for improvement for CABG through increased use of atrial revascularization and appropriate measures to minimize stroke.

The latest SYNTAX findings can inform the approach surgeons take with high-risk patients, they said. This should include “a discussion of these data, particularly in regard to survival.” And physicians should base their therapeutic recommendations on these data. “At present, there are data seeming to indicate that the majority of patients with three-vessel disease receiving invasive treatment in the United States are being treated with PCI, an outcome that is not congruent with these outcome findings,” they said.

Taking into consideration other SYNTAX analyses that have shown that completeness of revascularization is a determining factor in post-PCI outcomes, Dr. Mack and coauthors said that physicians should calculate the degree of coronary artery disease (CAD) left untreated after intervention, “and those patients who are likely to have a high residual SYNTAX score should be strongly considered for CABG.” Doctors should also focus “intensive efforts” on adherence to optimal medical therapy after both CABG and PCI.

“Finally, although there is a strong patient preference for a less-invasive treatment of their CAD, patients with advanced disease should be made aware that the choice of PCI puts them at an increased risk of death relative to CABG, and a full and transparent discussion should occur regarding the implications of their decision,” Dr. Mack and coauthors concluded.

They had no relevant financial relationships to disclose.

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