Fragmented QRS on electrocardiography as a predictor of myocardial scar in patients with hypertrophic cardiomyopathy.

BACKGROUND: Fragmented QRS (fQRS) and Q waves are ECG findings in patients with myocardial scar. fQRS is more sensitive than pathological Q waves in detecting myocardial fibrosis in patients with coronary artery disease (CAD). Cardiac magnetic resonance (CMR) imaging is used for the diagnosis and for quantifying scar tissue in patients with HCM. Our aim was to correlate ECG parameters like fQRS and Q waves with the presence of late gadolinium enhancement (LGE) assessed by contrast CMR imaging to elucidate ECG markers which might predict scar tissue in HCM.

METHODS: This study is a retrospective analysis which included 39 patients who were diagnosed/suspected to have HCM on echocardiography and referred for contrast CMR imaging at our centre between 2010 and 2016. Presence of fQRS was correlated with scar demonstrated by LGE on CMR.

RESULTS: Twenty four (66.67%) patients had asymmetrical septal hypertrophy, 7 (19.44%) patients had apical involvement while 5 (13.89%) had concentric pattern. Only 4 (11.11%) patients had pathological Q waves in contiguous leads on surface ECG while fQRS in two contiguous leads was present in 23 (63.89%) patients. Presence of fQRS was more in patients with LGE on CMR than those without (84.61 versus 10%, p<.001). When presence of LGE in specific segments (anterior, lateral and inferior) was correlated with corresponding ECG leads, all the three segments showed significant correlation. The overall sensitivity, specificity, PPV and NPV of fQRS for predicting scar tissue were 84.6, 90.0, 95.6 and 69.2%, respectively.

CONCLUSION: fQRS on surface ECG can be used as an indirect marker to predict the presence of fibrosis in HCM.