Background: Fragment QRS (fQRS) complex is a myocardial conduction abnormality that indicates myocardial scar. The significance of fQRS lies in the fact that it just requires a surface ECG for its recording and the value of information about the condition of the heart it dispenses based on the clinical setting. Objective: Our study aimed to investigate the relationship between FQRS exercise tolerant patients with heart failure with preserved ejection fraction. Patients and methods: The study was an observational cross-sectional study. It was conducted at the Cardiology Department, Zagazig University Hospitals. The studied sample consisted of 95 patients with diastolic dysfunction. All patients were stratified into two groups according to the presence or absence of fragmented QRS complex in resting surface ECG. Electrocardiogram, conventional echocardiographic examination, tissue doppler imaging, and 6 minutes walk test were done. Results: There was a statistically significant difference between 6 minutes walk test of heart failure with preserved ejection fraction patients with and without FQRS. In addition, we found that 6 minutes walk test is considered a good parameter to discriminate congestive heart failure patients with and without FQRS with a sensitivity of 81.5%, specificity of 69.6%, and accuracy of 72.9%. Conclusion: The value of FQRS in cardiology is much higher than what is being understood currently. FQRS is considered to be an indicator of myocardial fibrosis or scar tissue and has already been observed to be closely associated with a greater probability of adverse cardiac consequences and reduced tolerance of exercise in patients with HFpEF.