October 14, 2020
PROSPECT II Shows Benefit of NIRS-IVUS Imaging to Identify Vulnerable Plaque
October 14, 2020—New data from the PROSPECT II study shows that near-infrared spectroscopy intravascular ultrasound (NIRS-IVUS) intracoronary imaging can help identify angiographically nonobstructive lesions with high-risk characteristics for future adverse cardiac outcomes.
The findings were reported at TCT Connect, the 32nd annual Transcatheter Cardiovascular Therapeutics 2020 scientific symposium of the Cardiovascular Research Foundation held online October 14–18.
PROSPECT II was an investigator-sponsored multicenter, prospective, natural history study conducted at 16 centers in Sweden, Denmark, and Norway to validate the use of NIRS and IVUS imaging in identifying nonobstructive lipid-rich plaques that are prone to cause future cardiac events. In the PROSPECT study, a large plaque burden or small lumen area assessed by IVUS identified angiographically mild lesions at increased risk to cause future coronary events.
“In PROSPECT II, lipid-rich plaques, as detected by NIRS, identified angiographically mild nonflow-limiting lesions responsible for future coronary events,” commented PROSPECT II investigator David Erlinge, MD, in the TCT press release. Dr. Erlinge is Professor, Department of Cardiology, Clinical Sciences, Lund University at Skåne University Hospital in Malmö, Sweden. He continued, “High lipid content, along with large plaque burden and small lumen area, may be added as prognostic indices of vulnerable plaques that put patients at risk for adverse outcomes. Further studies prospectively utilizing this information are warranted to improve outcomes for high-risk patients with coronary artery disease.”
As noted in the TCT press release, lipid-rich fibroatheromas identified by IVUS can be predictive but plaque interpretation with this technique is not as precise. Lipid content may be more accurately measured by NIRS. Recent studies have suggested that lipid-rich plaques detected by intracoronary NIRS imaging are associated with adverse outcomes. Identifying these vulnerable plaques before they progress may help to inform pharmacologic or other strategies to stabilize the plaque.
In PROSPECT II, after successful treatment of all flow-limiting lesions in patients with recent myocardial infarction, imaging of all three coronary arteries was performed with a combination NIRS-IVUS catheter. The lipid content of nonculprit lesions was assessed by NIRS; also, IVUS assessment was performed.
The primary outcome was the covariate-adjusted rate of major adverse cardiac events (the composite of cardiac death, myocardial infarction, unstable angina, or progressive angina) adjudicated to have arisen from nonculprit lesions. The relationship between plaques with high lipid content, large plaque burden, and small lumen areas and patient-level and lesion-level events were tested hierarchically.
As summarized in the TCT announcement, a total of 3,629 untreated nonculprit lesions were prospectively characterized in 898 patients with myocardial infarction. Adverse events within 4 years occurred in 13.2% of patients, with a total of 8% of events arising from untreated nonculprit lesions with mean baseline diameter stenosis 46.9%.
The presence of highly lipidic lesions was an independent predictor of patient-level nonculprit events (adjusted odds ratio [OR], 2.27; 95% CI, 1.25-4.13) and lesion-specific events (adjusted OR, 7.83; 95% CI, 4.12-14.89). Large plaque burden and small lumen areas were also independent predictors of adverse events, reported TCT.