Background: Fragmented QRS (fQRS) complexes on 12-lead electrocardiography (ECG) have been reported to be predictors of cardiac events and all-cause mortality in coronary artery disease (CAD).

Aim: To investigate the relationship between fQRS complexes and SYNTAX and Gensini scores in patients with acute coronary syndrome (ACS).

Methods: A total of 302 patients (223 men and 79 women) with ACS (133 ST elevated myocardial infarction [STEMI], 107 non-STEMI [NSTEMI], and 62 unstable angina pectoris [USAP]) were evaluated retrospectively in this study. An fQRS pattern was found in 70 patients (fQRS group) but was not found in 232 patients (non-fQRS group). SYNTAX score > 22 and Gensini score > 20 were defined as high SYNTAX and Gensini scores. The relationship between the presence of fQRS on 12-lead ECG and SYNTAX and Gensini scores was assessed.

Results: SYNTAX score (p < 0.001), Gensini score (p < 0.001), NYHA class (p < 0.001), QRS duration (p < 0.001), number of disease vessels (p = 0.003), and high sensitive troponin T levels (p = 0.026) were significantly higher in the fQRS group. The number of fQRS leads (HR 5.79, 95% CI 2.78–12.06, p < 0.001, HR 3.41, 95% CI 1.32–8.78, p = 0.016, respectively) was found to be an independent predictor of high SYNTAX score and high Gensini score in multivariate analysis.

Conclusions: The number of fQRS leads on 12-lead ECG on admission is associated with the severity and complexity of CAD in patients with ACS.