The burden of vulnerable coronary plaque following acute coronary syndrome in older patients : evaluation utilising advanced intracoronary imaging techniques

Abstract

Objectives The burden of non-ST elevation acute coronary syndrome (NSTEACS) in older (≥75 years) patients is rising. However, there are few studies to date on the pattern of coronary disease in this cohort. Using intracoronary imaging, I aimed to evaluate the vulnerable plaque burden among older patients presenting with NSTEACS, establish its association with patient and lesion phenotypes, and explore determinants of adverse outcomes. Methods Prior to percutaneous coronary intervention (PCI), 3-vessel intracoronary imaging was performed with virtual histology intravascular ultrasound (VH IVUS) and optical coherence tomography (OCT). Angiographic, VH IVUS and OCT images were analysed offline and blinded to patient data. Major adverse cardiovascular events (MACE) at one year were defined as death, ACS, stroke, repeat unplanned revascularisation, and bleeding. Results Recruitment of older patients was successful, with 69.8% of approached patients recruited (91 patients, mean age 80.8 years, 63.7% male), and successful imaging performed in >70% of anatomically suitable vessels. There was a high success rate of PCI overall (90.4%). With increasing age, %atheroma volume (<79 years: 42.7% vs. 79-82 years: 43.4% vs. >82 years: 50.0%, p<0.001) and burden of thin-cap fibroatheroma (TCFA) (5.7% vs. 9.3% vs. 14.1%, p<0.001) increased. Men had a higher burden of atheroma on all modalities but plaque composition did not differ between the sexes. Calcification on VH IVUS increased with frailty (robust: 13.7% vs. pre-frail: 13.0% vs. frail: 17.7%, p=0.018). Vulnerable plaque features on OCT such as rupture, microchannels and TCFA clustered together, suggesting they form part of the same pathophysiological process. ii Calcification was initially associated with a reduction in the %stenosis of a lesion, mediated by a high rate of positive remodeling that slowed with severe calcification (R=0.363, p<0.001). Moderately calcified lesions had a higher residual %stenosis postPCI (23.1% vs. none: 14.2% vs. severe: 19.0%, p=0.014) and were associated with higher MACE at 1 year (low: 9.5% vs. moderate: 31.6% vs. high 12.0%, p=0.044), driven by ACS. Previously identified vulnerable TCFA did not predict MACE at 1 year in this cohort (p=0.291). Conclusions Even in high-risk older patients, PCI after NSTEACS is successful and associated with a low rate of MACE at 1 year. At no age does the accumulation of coronary plaque plateau but frailty, not age, was associated with increased calcification. Calcium is not an inert plaque component, but actively shapes vessel remodeling. Moderate calcification had the highest risk for adverse outcomes at 1 year due to recurrent ACS, suggesting that these patients may derive greater benefit from an aggressive invasive strategy.