SAN DIEGO– Complete revascularization of multivessel disease in patients hospitalized for ST-segment elevation MI improves long-term outcomes, although PCI of the culprit lesion only remains an option for some, the DANAMI3-PRIMULTI trial results suggest.

At 1 year, fractional flow reserve–guided complete revascularization significantly reduced the risk of all-cause death, nonfatal MI, and repeat revascularization, from 22% with infarct-only percutaneous coronary intervention (PCI) to 13%.

The reduction in the primary composite endpoint, however, was driven only by the need for fewer repeat revascularizations of non–infarct-related artery (IRA) lesions and not by hard endpoints.

“Therefore, although complete revascularization should be recommended, any condition that makes complex PCI unattractive may support a more conservative strategy of IRA PCI only,” principal investigator Thomas Engstrøm said at the American College of Cardiology/Cardiovascular Research Foundation Innovation in Intervention Summit.

Current guidelines support IRA-only PCI, although two contemporary studies – PRAMI and CvLPRIT – suggest that a preventive strategy of revascularization of all lesions in the coronary arteries improves outcomes, he noted.

DANAMI3-PRIMULTI (Third Danish Study of Optimal Acute Treatment of Patients With ST-Segment Elevation Myocardial Infarction: Primary PCI in Multivessel Disease) is the largest trial to date to examine this issue.

Investigators at two centers randomized 2,239 patients within 12 hours of STEMI to conventional primary PCI, ischemic postconditioning, or deferred stenting. Among 2,212 patients who had successful infarct-related artery PCI, 627 had multivessel disease and were further randomized to IRA PCI only or fractional flow reserve-guided complete revascularization. Multivessel disease was defined as greater than 50% stenosis in a non-IRA artery greater than 2 mm suitable for PCI.

Nonfatal MI occurred in 5% of patients in both groups, and all-cause death occurred in 4% of IRA-only patients and 5% of complete revascularization patients, reported Dr. Engstrøm, consultant cardiologist, Rigshospitalet, University of Copenhagen.

Ischemia-driven revascularizations were significantly more common in the IRA-only group, at 17%, compared with 5% in complete revascularization group, a significant difference. Notably, 40% of these repeat revascularizations were urgent on the basis of unstable angina, he said.

Panelist Sunil V. Rao, from Duke University in Durham, N.C., asked whether the knowledge that residual disease was left behind in half of the patients in the unblinded trial could potentially bias against the IRA-only arm.

Dr. Engstrøm acknowledged that “there may be a bias when the patients leave the hospital and know they have stenoses that are untreated,” but said great care was taken in the design of the trial because “we wanted to stress quite precisely the wording of the guidelines, which state that repeat revascularization could be either due to subjective or objective ischemia and to answer this question.”

DANAMI3-PRIMULTI’s modest patient population sets the stage for larger, more conclusive studies, but in the meantime will have an interesting impact on the U.S. guideline recommendation, currently a class III recommendation and suggestive of harm for treating additional lesions in the setting of acute MI, Dr. David Kandzari, director of interventional cardiology at the Piedmont Heart Center in Atlanta, said.

Dr. Kandzari echoed concerns that awareness of residual disease may have influenced the likelihood of repeat revascularizations, but also complimented the investigators on a thoughtful trial design that selected lesions based on clinically significant criteria and allowed non-infarct–related arteries to be treated in a staged fashion rather than mandating treatment at the time of PCI.

There was only one death between the index procedure and the additional PCI and this was caused by a cardiac rupture, and thus merely a result of the disease itself and not the staged approach, Dr. Engstrøm said in an interview.

“Of course, you can argue that full revascularization at the time of the index lesion may support even the IRA territory resulting in smaller final infarcts,” he added. “We find this, however, unlikely since both groups ended up with quite small infarct sequelae: LVEF 50% in both groups.”

Panelist Theodore A. Bass, chief of cardiology at the University of Florida in Jacksonville, said the trial “further confirms emerging data that in the same setting, or at least the same hospitalization, more aggressive treatment may be warranted in certain patients.”

“Our data support that complete revascularization can be done without harm and with a very good outcome,” Dr. Engstrøm said. “So you might argue: Why wait for the readmission either in the case of stable angina or in the indication of unstable angina with a need for urgent PCI?”

Dr. Engstrøm reported having no financial disclosures. Dr. Rao reported consulting fees/honoraria from Terumo Medical and the Medicines Company and research grants from Bellerophon Therapeutics. Dr. Kandzari reported consultant fees/honoraria from Boston Scientific, Medtronic, Micell Technologies, and Thoratec. Dr. Bass reported consulting fees/honoraria from Merck.

pwendling@frontlinemedcom.com

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