Results from SYNTAX trial show PCI/CABG differences

The SYNTAX trial is a large-scale investigation with two components — a randomized clinical trial and a separate registry, with 62 European heart centers participating and 23 centers in the U.S.

Each center had an investigative team co-led by a surgeon and an interventionalist.

To respond to criticisms that trial data for DES to this point have used carefully selected patient populations, the SYNTAX trial is an "all-comers" design, taking on all patients who have severe cardiac disease and are de novo, meaning they have never had a surgical procedure of any kind to address that condition.

The randomized trial component

Patients qualifying for the randomized trial component had a blockage to the left main artery as well as from one to three blocked vessels, or else had three blocked vessels. There were no other exclusion criteria.

"These are very sick patients," said lead investigator Patrick Serruys, MD, of Erasmus University Medical Center (Rotterdam, the Netherlands), who reported 1,800 patients were enrolled, of whom 897 were given CABG and 903 received a DES during PCI.

In the randomized cohort, there were nearly identical safety outcomes where the combined scores for death, CVA and MI came in at 7.6% for PCI and 7.7% for CABG.

But there were significantly higher rates of revascularization in the PCI group, with 13.7% going back to the operating room, while just 5.9% of the CABG patients had such complications.

Significantly, the 85% of the PCI patients who went back received PCI a second time and still did not need to be cut open to fix the complications.

In this patient cohort, the final result for MACE including the revascularization was 17.8% for PCI vs. 12.1% for CABG.

These differences are not startling and PCI might have squeaked by the hard endpoint of the study, staying below the absolute cut-off difference of 6.6% for non-inferiority.

The SYNTAX registry component

The registry component, which is a real-world reflection of the use of DES, was the downfall for PCI in this trial.

Frederick Mohr, of the Heart Center at the University of Leipzig in Germany, led the registry component of the trial and explained these were patients who could not be randomlized and were sorted according to their ability to not withstand one or the other of the procedures, being either inoperable and therefore having the PCI procedure, or else having anatomical or health problems that would not permit PCI and therefore were sent for CABG.

Of the total 1,275 patients enrolled in the registry, only 198 received PCI with 1,077 undergoing bypass.

The detailed results of the MACE components in the registry show 2.5% death rate for CABG vs. 7.3% for PCI. The overall rate of death for the 1 million cardiovascular surgeries performed in Europe each year hovers around 2%, so the PCI result is troublesome.

PCI turned in higher CVA incidents as well with 4.2% vs. 2.5% for CABG, while for MI there were no patients reporting a heart attack in the 12 months following the procedure, whereas 2.5% of CABG patients experienced an incident.

Revascularization, again, was the problem, with only 3% of CABG patients needing to return to the operating room vs. 12% of PCI patients doing so.

In this patient cohort, the final MACE rate, including the revascularization, was 20.4% for PCI vs. 8.8% for CABG.

— John Brosky, European Editor