Prognostic significance of angiography-derived index of microcirculatory resistance assessment after rotational atherectomy in patients with severely calcified lesions.

Coronary microcirculatory dysfunction (CMD) is a known predictor of adverse outcomes after percutaneous coronary intervention (PCI). However, the prognostic significance of CMD in patients with severely calcified lesions treated with rotational atherectomy (RA) remains unclear. We retrospectively studied consecutive chronic coronary syndrome patients who underwent PCI with RA followed by second-generation drug-eluting stent (DES) implantation. CMD was evaluated by angiography-derived index of microcirculatory resistance (IMR), calculated from the quantitative flow ratio (QFR) obtained immediately after PCI without hyperemia. The primary outcome was the occurrence of major adverse cardiovascular events (MACE) within 2 years, including cardiovascular death, spontaneous myocardial infarction, and target vessel revascularization. Among the 128 enrolled patients, 22 (17.2%) experienced MACE. Post-IMR was significantly higher in patients who experienced MACE than in those who did not (39.3 ± 12.5 vs. 30.4 ± 9.8, p < 0.001). Increased post-IMR was independently associated with MACE (hazard ratio, 1.05; 95% confidence interval [CI]: 1.02-1.09, p = 0.004). Receiver operating characteristic curve analysis identified optimal cutoff values of 40.6 for post-IMR to predict MACE (area under the curve 0.72, 95% CI: 0.58-0.86). Including high post-IMR (> 40U), along with clinical risk factors and QFR findings, significantly improved the discriminatory and reclassification ability to identify the risk of MACE after RA. IMR measured immediately after the PCI with RA followed by second-generation DES implantation is a valuable tool for risk stratification in patients with severely calcified lesions.