Introduction: Heart failure with preserved ejection fraction (HFpEF) is still unresolved problem. Interatrial dyssynchrony was associated with worse clinical status in such patients. Tricuspid Annular Plane Systolic Excursion to Pulmonary Artery Systolic Pressure (TAPSE/PASP) Ratio could be correlated with intra- and interatrial conduction time in patients with HFpEF. Methods: In 73 consecutive patients with HFpEF, we measured of right ventricular TAPSE, PASP, and parameters of atrial dyssynchrony. We assessed atrial dyssynchrony by measuring the difference between the times from the electrocardiogram P wave onset to the tissue doppler A′ wave onset (PA′ interval) at the levels of lateral mitral, septal mitral, and tricuspid annuli. We studied the association of such dyssynchrony with TAPSE/PASP ratio in patients with HFpEF. Results: Based on the median of TAPSE/PASP ratio, 73 patients were categorized into two groups as having TAPSE/PASP ≤0.48 (group I) or having TAPSE/PASP >0.48 (group II). Group I patients had higher NYHA class (p<0.05), higher brain natriuretic peptide (<0.01), higher left ventricular mass index (p<0.01), greater left atrial volume index (p<0.003), reduced left atrial ejection fraction (p<0.01), and higher E/e′ ratio (p<0.01). Furthermore, group I patients had prolonged mitral and tricuspid PA′ intervals (p<0.001) and significantly increased left and right atrial dyssynchrony (p<0.001) compared with group II patient. TAPSE/PASP ratio correlated with left atrial dyssynchrony (r=−0.53, p<0.001), right atrial dyssynchrony (r=−0.55, p<0.001) and with interatrial dyssynchrony (r=−0.48, p<0.005). Conclusion: In patients with HFpEF with TAPSE/PASP < 0.48, had prolonged right atrial, left atrial, and interatrial dyssynchrony which is a risk marker for arrhythmia. Therefore, TAPSE/PASP ratio might help to improve risk stratification to predict outcome in HFpEF patients