Ruptured Plaque Signals Worse Prognosis in ACS Patients

Among patients with ACS, those with ruptured plaque at the culprit lesion have poorer outcomes over the long term compared with those with intact fibrous caps, according to study published online February 19, 2015, ahead of print in the European Heart Journal.

Giampaolo Niccoli, MD, PhD, of the Catholic University of the Sacred Heart (Rome, Italy), and colleagues enrolled 139 consecutive ACS patients (mean age 64.3 years; 73.4% male) who were admitted to the coronary care unit at the Policlinico Universitario Agostino Gemelli and San Giovanni Addolorata Hospital (Rome, Italy). All underwent coronary angiography followed by interpretable OCT from January 2010 to September 2012. The majority of patients (66.2%) had NSTE-ACS.

Overall, 59% had ruptured plaque at the culprit lesion, with intact fibrous caps seen in the remainder. Those with plaque rupture had thinner fibrous caps, a higher maximum lipid arc, a longer calcified segment in the culprit vessel, and higher rates of thrombus and lipid-rich plaque at the culprit lesion.

There were no differences in clinical, angiographic, or procedural variables based on plaque morphology. However, the rate of MACE (cardiac death, nonfatal MI, rehospitalization due to unstable or progressive angina, and clinically driven TVR) was higher among patients with ruptured plaque through a mean follow-up of 2.6 years (table 1). Rates of each of the individual endpoints, except for cardiac death, were also numerically greater in that group.

Multivariate analysis revealed that the presence of ruptured plaque was the only independent predictor of MACE (OR 3.74; 95% CI 1.36-9.74).

Plaque Features Drive Outcome Disparity

The differences between plaques that were ruptured and those with intact fibrous caps observed in the study are consistent with prior research using OCT, IVUS, or multislice CT, according to Dr. Niccoli and colleagues.

“Importantly, a recent study by Vergallo et al showed that patients with [plaque rupture in addition to ACS] more frequently [had thin cap fibroatheroma] in the entire coronary tree explored by 3-vessel OCT,” the authors write. “Moreover, Ozaki et al showed that patients with [plaque rupture] more frequently [had] positively remodeled plaques with large plaque burden when compared with those [who had] an [intact fibrous cap].”

Taken together, “these observations suggest that patients with [plaque rupture] share a common phenotype of more diffuse and vulnerable atherosclerosis,” the researchers note.

The higher MACE rate seen with plaque rupture was primarily driven by differences in TVR and rehospitalization for unstable angina, they point out, “suggesting that both stent failure and disease progression are enhanced in [those patients].”

Outcomes might also be better among patients with intact fibrous caps because “they are largely constituted by OCT-defined plaque erosion where a single occasional thrombotic stimulus occurs,” the authors write. “Thus, its recurrence might well be prevented by antithrombotic therapies without coronary stenting, as recently suggested.”

Finally, they note, “the better prognosis of patients with [intact fibrous caps] associated with smooth stenosis without rupture or thrombus may be due to the use of vasodilators that prevent coronary vasoconstriction recurrence or [the relief] of ischemia by coronary stenting in high-grade fixed stenosis.”

Regardless of the reasons for the disparity in outcomes, “different tailored therapies should be investigated in these profoundly different patient subsets,” they argue.

Source: 
Niccoli G, Montone RA, Di Vito L, et al. Plaque rupture and intact fibrous cap assessed by optical coherence tomography portend different outcomes in patients with acute coronary syndrome. Eur Heart J. 2015;Epub ahead of print.

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