Impact of underlying causes of acute coronary syndrome on clinical outcomes after percutaneous coronary intervention: a landmark analysis from the OCT-guided PCI registry (TACTICS registry)

Background Optical coherence tomography (OCT) allows for the diagnosis of underlying causes of acute coronary syndrome (ACS), such as plaque rupture (PR), plaque erosion (PE), and calcified nodule (CN), which can serve as predictors of subsequent clinical events. However, the duration and extent of its impact remain unclear. Purpose This study aimed to examine the relationship between the underlying causes of ACS and 2-year clinical outcomes following emergency PCI. Methods In the TACTICS registry, a prospective multicenter observational study, ACS patients who underwent OCT-guided emergency PCI within 24 hours of symptom onset were enrolled. A total of 617 patients were diagnosed with PR, PE, or CN. Major adverse cardiac events (MACE) were defined as a composite of cardiovascular death, myocardial infarction, heart failure, or ischemia-driven revascularization, and were adjudicated by an independent clinical events committee. Results The mean age was 66.1 ± 12.8 years, and 81% of the participants were male. The door-to-balloon time was 75 [54, 149] mins. Post OCT findings showed the mean minimum stent area and stent expansion were 6.2 ± 2.4 mm2 and 75.2 ± 17.9 %, respectively, with no significant differences observed among the three underlying causes. During the follow-up period (736 days, interquartile range: 709–1208), MACE occurred most frequently in patients with CN, followed by PR and PE, within the first 3 months. Beyond 3 months, MACE continued to occur most frequently and significantly in patients with CN; however, the risk of MACE did not differ between those with PR and PE (Figure). On multivariate Cox regression analysis, while CN and PR increased MACE compared to PE within the 3 months (CN [HR, 9.97 [95% CI, 2.81–35.3], P<0.001]; PR [HR, 3.10 [95% CI, 1.09–8.84], P=0.034]; PE as reference), CN was observed as the independent predictor of the MACE beyond 3 months (CN [HR, 6.09 [95% CI, 2.36–15.7], P<0.001]; PR [HR, 1.23 [95% CI, 0.61–2.46], P=0.557]; PE as reference). Conclusion Compared to patients with PE, those with CN exhibited a significantly worse prognosis over the long term, while those with PR experienced an increased risk of MACE only during the early phase. The underlying cause of ACS plays a crucial role in stratifying the future risk of MACE, both in terms of its extent and duration.