Microcirculatory resistance index based on a single angiographic view predicts long-term prognosis following rotational atherectomy in patients with acute coronary syndrome

To explore the long-term predictive value of the angiographic microcirculatory resistance (AMR) index for patients with acute coronary syndrome (ACS) undergoing rotational atherectomy (RA). A total of 344 ACS patients undergoing RA during percutaneous coronary intervention (PCI) at Nanjing Drum Tower Hospital between December 1, 2011 and December 1, 2022 were retrospectively analyzed. AMR of the target vessel was measured, and the incidence of major adverse cardiac and cerebral events (MACCEs) was analyzed as the primary endpoints. MACCEs encompassed cardiovascular mortality, non-fatal myocardial infarction (MI), target vessel revascularization (TVR), worsening heart failure (WHF), and ischemic stroke (IS). Patients were divided into the MACCEs group and the non-MACCEs group based on the occurrence of MACCEs. Univariate and multivariate Cox regression analyses were conducted to determine factors linked to MACCEs. Moreover, patients categorized based on the median AMR value into the high-AMR group and the low-AMR group. We conducted Kaplan-Meier curve analysis to assess the differences in the cumulative event rates between patients in the high-AMR group and the low-AMR group during long-term follow-up. Utilizing restricted cubic spline (RCS) curves, we further validated the relationship between AMR and the occurrence of MACCEs. After the completion of a median follow-up time of 39 months, 268 ACS patients undergoing RA were included in the final analysis, of whom 53 (19.78%) experienced MACCEs. Compared with the non-MACCEs group, the MACCEs group exhibited a significantly higher AMR post-RA (P < 0.05). There was no statistically significant difference in clinical presentations between patients in the high-AMR and low-AMR groups. The multivariate Cox regression analysis revealed that AMR following RA was an independent predictor of MACCEs during long-term follow-up (hazard ratio [HR]: 2.364, 95% confidence intervals: 1.394–4.009; P < 0.01). Furthermore, restricted cubic spline analysis revealed a positive correlation between the cumulative risk of primary endpoints and increasing AMR levels. Notably, utilizing AMR as a continuous variable revealed a rapid elevation in HRs for MACCEs within the higher range of AMR (AMR > 2.278) in the long-term. Elevated AMR post-RA predicts an increased risk of MACCEs during long-term follow-up in ACS patients.