The Right ventricle has a higher coronary blood flow during "SYSTOLE"
Source 1 :
Coronary blood flow is unique in that there is interruption of flow during systole (mechnical compression of vessels by myocardial contraction. Coronary blood flow occurs predominatly during diastole when cardiac muscle relaxes and no longer obstructs blood flow through ventricular vessels. Conversely, right coronary arterial flow rate is highest during systole, because th aortic pressure driving flow increases more during systole (from 80 to 120mmHg) that the right ventricular pressure which opposes flow (from 0 to 25mmHg)
During systole, especially on the left side of the heart, the pressure within the coronary artery secondary to extravascular compression from the squeezing effect of the contracting myocardium virtually eliminates antegrade coronary blood flow. This situation is diagrammed in Figure 16–23, in which the coronary blood flow goes to zero just prior to ventricular ejection, corresponding to isovolumic contraction and increased extravascular compression. 104 Conversely, coronary blood flow through the left side is maximal during early diastole, corresponding to the period of isovolumic relaxation (see Fig. 16–8, E to A) and minimal extravascular compression. Coronary blood flow through the right side, however, is maximal during peak systole, because developed pressure and consequently extravascular compression within the RV are considerably less than in the LV, thus allowing for antegrade flow during both systole and diastole
Here is the Graph