Microcirculatory dysfunction in patients with acute anterior myocardial infarction combined with new complete right bundle branch block

Objective This study sought to investigate clinical characteristics of acute anterior ST-segment elevation myocardial infarction (STEMI) patients complicated by new complete right bundle branch block (CRBBB) and evaluate the occurrence of microcirculatory dysfunction post-percutaneous coronary intervention (PCI). Methods Retrospective analysis was conducted on 261 patients with acute anterior STEMI, differentiating 40 with concurrent new CRBBB (CRBBB group) from 221 without (no-CRBBB group). Data on demographics and hospitalization were collected, and clinical features and prognoses were compared. Post-PCI microcirculatory function was further characterized using the index of microcirculatory resistance (caIMR), TIMI grade flow, corrected TIMI flow frame count (CTFC) of the infarct-related artery, and ST segment regression in ECG (STR). Results Age, Killip class, GLUC, TG, HDL, BUN, GFR, AST, ALT, WBC, TNI at admission significantly differed between groups (P < 0.05). Incidences of in-hospital major adverse cardiovascular events and LVEF showed significant disparities (P < 0.05). The CRBBB group exhibited higher CaIMR, lower TIMI flow, and STR (P < 0.05). Multivariate analysis indicated TIMI ≤ grade 2 (OR = 6.833, 95% CI: 1.009 ~ 46.287, P = 0.049), STR ≥ 50% (OR = 0.176, 95% CI: 0.051 ~ 0.606, P = 0.006), CTFC (OR = 1.079, 95% CI: 1.009 ~ 1.155, P = 0.027), and caIMR (OR = 1.120, 95% CI: 1.059 ~ 1.185, P < 0.001)were independently linked to CRBBB post-PCI. The Killip class and CaIMR exhibited high predictive value for the development of new combined CRBBB in acute anterior STEMI, with an area under the curve of 82.5% (P < 0.001) and 78.1% (P < 0.001), respectively. Conclusion In patients with acute anterior STEMI, those with new CRBBB are at an increased likelihood of experiencing microcirculatory dysfunction.