PHILADELPHIA – Nearly half of patients with ST-elevation MI and multivessel coronary artery disease in the landmark COMPLETE trial had an obstructive coronary lesion with vulnerable plaque morphology in a segment far from the culprit lesion, , reported at the American Heart Association scientific sessions.
This novel finding from an optical coherence tomography (OCT) substudy of COMPLETE provides a likely mechanistic explanation for the major clinical benefits documented in the full COMPLETE trial, noted Dr. Pinilla-Echeverri, a cardiologist at the Population Health Research Institute at McMaster University, Hamilton, Ont.
COMPLETE was a multinational trial which randomized 4,041 ST-elevation MI (STEMI) patients with multivessel disease to culprit lesion–only percutaneous coronary intervention (PCI) or additional routine angiography–guided staged PCI of nonculprit obstructive lesions with at least 70% stenosis. As previously reported, the risk of the coprimary composite endpoint comprising cardiovascular death, new MI, or ischemia-driven revascularization was reduced by 49% over 3 years of follow-up in the group with staged PCI of nonculprit lesions, with an impressive number needed to treat of just 13 ().
Dr. Pinella-Echeverri reported on the 93 patients who participated in the OCT substudy, the purpose of which was to determine the prevalence of high-risk, vulnerable plaque in obstructive and nonobstructive nonculprit lesions. For this purpose, vulnerable plaque was defined as thin-cap fibroatheroma (TCFA), a coronary lesion known to pose high risk of worsening stenosis, plaque rupture, and cardiovascular events.
Of note, these 93 patients had a total of 425 diseased segments: 150 obstructive and 275 nonobstructive.
“This is reassuring that the concept of acute coronary syndrome implies a diffuse pathophysiology of affecting not only the culprit segment but the coronary vasculature as a whole,” Dr. Pinella-Echeverri observed.
The main study finding, however, was that TCFA was significantly more prevalent in obstructive, compared with nonobstructive, nonculprit lesions by a margin of 35% to 23%. The obstructive and nonobstructive TCFA lesions had a similar lipid-rich composition; however, the obstructive ones were significantly longer and had a smaller mean lumen area.
When breaking down the prevalence of TCFA per patient, 47% of patients had a nonculprit obstructive lesion with vulnerable plaque morphology. Another 20% had nonobstructive TCFA lesions. And only 32% of the STEMI patients had no TCFA in their obstructive or nonobstructive segments.
Discussant, PhD, commented: “This [OCT substudy result] immediately explains the clinical benefit observed with preventive PCI in STEMI patients with obstructive multivessel disease.”
The finding that 20% of the STEMI patients had nonobstructive lesions with vulnerable plaque morphology by OCT provides powerful support for the current guideline-recommended strategy of immediately starting STEMI patients on intensive lipid-lowering therapy, added Dr. Van de Werf, professor of medicine at the Catholic University of Leuven (Belgium).
He argued that the decision to revascularize nonculprit lesions by means of PCI versus the more complete revascularization achieved via coronary artery bypass graft surgery shouldn’t be made during the initial primary PCI, citing evidence that when the decision gets made at that time, coronary artery bypass grafting (CABG) is less likely to be chosen.
“I believe that OCT and [fractional flow reserve] should not be performed during the index primary PCI, not only for the comfort of the patient, but also for the better selection of complete revascularization. Interventional cardiologists should not forget that CABG might be a better revascularization treatment in some cases, such as left main disease and diabetes mellitus,” the cardiologist cautioned.
The COMPLETE OCT Substudy was supported by Abbott Vascular, the Population Health Research Institute, Hamilton Health Sciences, and the Canadian Institutes of Health Research.