Severity scale of coronary microvascular obstruction (no-reflow) during percutaneous coronary interventions in myocardial infarction patients

Introduction: There is no scale that combines the traditional criteria of coronary microvascular obstruction (CMVO, no-reflow phenomenon) to effectively assess the severity and prognosis of this complication.Objective: To develop and evaluate the severity scale of CMVO during percutaneous coronary intervention (PCI) for myocardial infarction (MI).Methods: The cohort study included 203 patients diagnosed with type 1 MI and CMVO during PCI. The CMVO criterion was TIMI flow grade (TFG) <3 points. Using the proposed "CMVO Severity Scale" (CMVO-SS), three groups of patients were identified. CMVO grade 1 (mild): TFG 2 points, Myocardial blush grade (MBG) 2–3 points, ST segment resolution after PCI (rST) >70%. CMVO grade 2 (moderate): TFG 2 points, MBG 0–1 points or rST <70%. CMVO grade 3 (severe): TFG 0-1 points.Results: Distribution of groups with CMVO of the 1st, 2nd, and 3rd grade is 65 (32%) / 88 (43%) / 50 (25%) patients, respectively. Outcomes by group: acute heart failure grade 3–4 — 2 (3%) / 11 (13%) / 14 (28%), P < .001; ejection fraction — 48 [44; 53] % / 46 [40; 50] % / 42 [39; 49] %, P = .004; in-hospital death — 1 (1.5%) / 12 (13.6%) / 16 (32.0%), P < .001; two-year death — 8 (12.3%) / 19 (21.6%) / 22 (44.0%), P < .001. The multivariate analysis revealed a two-year death odds ratio for the CMVO-SS of 2.40 [95% CI 1.23–5.17], P = .009. Two-year survival probability with CMVO-SS grade 1 was 87.7%, grade 2 — 78.4%, grade 3 — 56.0% (P < .001).Conclusion: The proposed CMVO severity scale is associated with adverse in-hospital outcomes and two-year mortality. Received 15 May 2023. Revised 27 September 2023. Accepted 24 October 2023. Funding: The study was supported by the "Priority 2030" program. Conflict of interest: The authors declare no conflict of interest. Contribution of the authorsConception and study design: A.A. Frolov, E.G. Sharabrin, I.G. PochinkaData collection and analysis: A.A. Frolov, I.A. Frolov, K.V. KuzmichevStatistical analysis: A.A. Frolov, I.A. Frolov, K.V. KuzmichevDrafting the article: A.A. Frolov, I.G. Pochinka, I.A. FrolovCritical revision of the article: I.G. Pochinka, A.S. Mukhin, E.G. Sharabrin, V.N. SinyutinFinal approval of the version to be published: A.A. Frolov, I.G. Pochinka, I.A. Frolov, K.V. Kuzmichev, A.S. Mukhin, E.G. Sharabrin, V.N. Sinyutin