Discussion
To our knowledge, this study is the first to evaluate the relationship between f-QRS and microvascular dysfunction in inferior MI patients who underwent successful PPCI. In this study, the presence of f-QRS was demonstrated in patients with impaired microvascular perfusion despite normal TIMI flow. Multivariate logistic regression models revealed that fragmented QRS is the development of myocardial blushing.
Fragmented QRS represents myocardial scarring and has been found to be associated with poor prognostic outcomes in heart disease (5,19-22). Das et al. found that all causes of death and cardiac events were higher in patients with fragmented QRS compared to patients with non-fragmented QRS (5). In addition, a recent meta-analysis showed that initially fragmented QRS was associated with increased all-cause deaths in heart failure patients with reduced ejection fraction (23). In our study, we found that ejection fraction was lower in patients with fragmented QRS. Ejection fraction is an important parameter in determining the short- and long-term prognosis.
In this study, fragmented QRS after angioplasty was associated with microvascular dysfunction in patients with acute inferior myocardial infarction whose infarct-related artery is the right coronary artery, as evidenced by angiographic results. Impaired microvascular perfusion was significantly associated with adverse cardiovascular events and mortality in patients with acute myocardial infarction. The success of primary PCI in myocardial infarction is assessed by different methods such as ST segment resolution, TIMI flow, and MBG. These microvascular perfusion markers represent a better predictor of clinical outcomes (12,13). In this study, we used ST segment resolution and MBG to assess the success of reperfusion therapy. We found that impaired microvascular reperfusion was higher in patients with fragmented QRS. Similarly, previous studies have shown a negative relationship between fragmented QRS and reperfusion parameters (14,15,16). In addition, Sridharan et al. found that fragmented QRS predicted impaired microvascular myocardial perfusion as assessed by ST segment resolution (17). In another study, Fatma et al. found that the presence of fragmented QRS in patients with myocardial infarction was associated with inadequate myocardial reperfusion, and they recommended its use as a simple, non-invasive parameter to evaluate myocardial perfusion (18).
Microvascular dysfunction is responsible for morbidity and mortality in many different cardiovascular diseases. Fibrosis is caused by irreversible damage to the cellular elements of the microvascular bed that feed the myocardium. This leads to delays in interventricular conduction. Thus, it may cause fragmented QRS formation. Therefore, it is possible that f-QRS represent impulse conduction abnormalities and create a setting for malignant reentrant ventricular arrhythmias and death. Das et al. showed that f-QRS in patients with coronary artery disease was associated with ventricular conduction delay due to myocardial scar detected by myocardial single photon emission tomography (24). In addition, in patients with known coronary artery disease, f-QRS was associated with major adverse cardiac events and was demonstrated as an independent predictor for all-cause mortality, and f-QRS was found to be associated with significantly higher arrhythmic events (25). We can say that the f-QRS seen on the ECG represents the conduction delay caused by the inhomogeneous activation of the ventricles due to myocardial scar.