Introduction: Echocardiography is used as a useful and common method to assess Left Ventricular and Right Ventricular (LV and RV) systolic and diastolic functions. Valsalva Maneuver (VM) with the increase in the intra-thoracic and intra-abdominal pressure is often used as an uncomplicated, cost-effective and non-invasive technique for diagnosing clinical conditions such as heart murmurs. However, in terms of echocardiography, the use of VM has been limited to only a few parameters for many years. In contrast, blood level of N-Terminal Pro-BType Natriuretic Peptide (NT Pro-BNP) indirectly discriminates normal or high ventricular Filling Pressure (FP). This study aimed at providing a comprehensive review of the technique as well as comparing the VM effect in ACS patients; with and without elevated FP on either RV or LV diastolic and systolic echocardiographic parameters. Methods: Thirty-eight patients, who were diagnosed with possible ACS; unstable angina pectoris, NSTEMI and STEMI, underwent coronary angiography enrolled in this double-blinded clinical trial study. The mild Coronary Artery Disease (CAD) with normal NT Pro-BNP levels were included in study group one and cases with significant CAD and high level of NT Pro-BNP who underwent PCI were included in study group two. All the systolic and diastolic indicators of both ventricles, totaling twenty-four parameters which have been previously mentioned in the academic literature, have been evaluated; once before valsalva and once during second stage of the maneuver. Echocardiography is performed by an advanced echo machine and by an expert cardiologist-echocardiographer; the recorded images were reviewed by the second echocardiographer separately.Results: Between the two groups, LV parameter analysis showed significant difference in LV EF pre and post VM. However, there was a statistically insignificant difference regarding other systolic as well as diastolic parameters. Between the two groups, RV parameters analysis indicated no significant difference regarding systolic and diastolic parameters pre and post VM.Conclusion: This research for the first time assessed post VM changes in four chambers as well as mitral and tricuspid valves parameters in ACS patients with normal versus high level of FP. Previously, LV diastolic dysfunction and Doppler mitral inflow pattern correlation with VM were verified. In the present study, in addition to those known findings from before-except the LV Ejection Fraction (LVEF) that showed there was statistically significant difference in pre-and post-VM-other systolic parameters, as well as diastolic indicators in either RV and LV, were identical. Therefore, we do not recommend conducting valsalva maneuver on the rest of the other parameters to diagnose systolic and diastolic dysfunction in ACS patients with mild versus significant CAD who were assumed to have normal or elevated filling pressures.