Evolution of Fragmented QRS in Patients with New-Onset Left Bundle Branch Block Acute Coronary Syndrome Undergoing Primary Percutaneous Coronary Intervention

Background: The lack of “ST segment resolution sign” after primary PCI represents one of the challenges in diagno-sis and management of patients with acute coronary syndrome (ACS) presenting with left bundle branch block (LBBB). The evolution of fragmented QRS (fQRS) in non-LBBB ACS pa-tients was found to be associated with sub-optimal revasculari-zation and poor prognosis. Aim of Study: This study aimed to assess clinical and angi-ographic factors associated with the evolution of fQRS in ACS patients presenting with LBBB. Patients and Methods: This prospectively studied 100 pa-tients with ACS presenting with LBBB and treated with pri-mary PCI. Serial ECGs were obtained over the first 2 days and examined for evolution (group 1) or absence/resolution (group 2) of fQRS. Clinical and angiographic data of groups 1 were analyzed. Results: Evolution of fQRS occured in 39 (39%) of patients (group 1). In this group, higher percentage of male patients (p=0.004), higher rate of current smoking (p=0.04), higher ad-mission SBP and Killip class (p=0.031 and <0.001; respective-ly), higher admission HsTnT and CK-MB (p<0.001; for each), lower LVEF at discharge (p<0.001), longer pain-to-door time (p=0.01) and lower MBG (p<0.001) were found in group 1. On regression analysis, presence of MBG 0-1, lower LVEF, higher admission SBP, higher admission CK-MB, and longer pain to door time were found to be independently associated with evo-lution of QRS. Conclusions: Evolution of fQRS in ACS patients present-ing with LBBB is independently associated with lower LV function and impaired microvascular perfusion. So, fQRS, as asimple marker, may be useful instratification of high-risk pa-tients with increased extent of infarcted myocardium in LBBB ACS.