Objectives: The QRS complex fragmentations (fQRS) frequently seen on admission electrocardiograms (ECGs) with narrow or wide QRS complex are associated with increased morbidity and mortality. The causative relationship between fQRS and cardiac fibrosis is known, but the relation of fragmented QRS before and after primary percutaneous coronary intervention (p-PCI) with myocardial infarction and reperfusion parameters has not been studied until now.
Study design: The study included 184 consecutive patients with ST elevation myocardial infarction (STEMI) who underwent p-PCI. Presence or absence of fQRS on pre- and post-PCI ECGs and its change following PCI were investigated. In addition, independent predictors of fQRS were also investigated. Patients with significant organic valve disease and patients having any QRS morphology with QRS duration ?120 ms as well as patients with permanent pacemakers were excluded from the study.
Results: Patients with fQRS on admission ECG had higher leukocyte counts (p=0.001), higher CK-MB (p=0.001) and troponin levels (p=0.005), increased pain to balloon time (p=0.004), higher Killip score (p<0.001), prolonged QRS time (p<0.001), higher Gensini score (p<0.001) and more frequent Q waves on ECG (p<0.001) in comparison to patients with non-fragmented QRS. In addition, these patients usually had an infarction of anterior territory related to a lesion in proximal LAD and wider jeopardized myocardium (p<0.001). fQRS was significantly related to infarction and myocardial reperfusion parameters before and after p-PCI. In the setting of STEMI, absence of fQRS on admission ECG predicted increased ST resolution, higher reduction in QRS duration, and better myocardial reperfusion.
Conclusion: FQRS may be useful in identifying patients at higher cardiac risk with larger areas of ischemic jeopardized or necrotic myocardium.