Interaction between coronary lesion complexity and coronary microvascular dysfunction in the prognosis of NSTEMI patients.

BACKGROUND

The prognostic value of the American College of Cardiology/American Heart Association (ACC/AHA) lesion classification in NSTEMI remains insufficiently investigated, especially regarding its interaction with coronary microvascular disease (CMD).

METHODS

In 2212 NSTEMI patients, we evaluated lesion complexity by applying the modified ACC/AHA classification system and then measured post-PCI angio-IMR. The primary endpoint was major adverse cardiovascular events (MACE) at 2 years.

RESULTS

Patients with complex lesions demonstrated substantially elevated 2-year MACE rates compared to those with simple lesions (13.5% vs 7.5%, P < 0.001). Lesion complexity independently predicted MACE [HR 1.48 (95% CI (1.09-2.00)), P = 0.011]. Notably, the addition of lesion classification to a model containing the GRACE score and other clinical factors significantly improved risk prediction [C-index 0.708 (95% CI (0.672-0.744)) vs 0.693 (95% CI (0.655-0.730)), P = 0.017)]. Among non-CMD patients, complex lesions were correlated with the higher MACE incidence (10.50% vs 6.20%, P = 0.002), whereas no significant difference was observed in CMD patients (37.80% vs 26.00%, P = 0.166). Notably, CMD showed a strong association with complex lesions [OR 1.74 (95% CI (1.22-2.48)), P = 0.002]. Mediation analysis indicated that CMD accounted for 17% of the total effect of lesion complexity on MACE [proportion of effect 0.17 (95% CI (0. 07-0.39)), P = 0.002].

CONCLUSIONS

The American College of Cardiology/American Heart Association lesion classification effectively stratifies risk in non-ST-segment elevation myocardial infarction, particularly among patients without coronary microvascular disease. Coronary microvascular disease is independently associated with complex coronary lesions and mediates approximately 17% of their adverse prognostic impact on major adverse cardiovascular events.