A novel HeartPatch direct cardiac compression (DCC) device has been shown to effectively restore circulatory parameters in sheep with acute heart failure (HF). Its effect on the coronary circulation and myocardial perfusion, however, remains uncertain. The effect of DCC assist on coronary artery blood flow (CABF) and its patterns in acute HF sheep were examined in this study. Ten sheep (51 +/- 6 kg) were implanted with a heart patch on each of the left ventricular and right ventricular free walls 1 week before study. Stable HF [cardiac output (CO) at 51 +/- 8% of baseline] induced by intravenous esmolol resulted in CABF decreasing to 53 +/- 16% of baseline (p < 0.001). DCC device activation did not alter CABF (54 +/- 15% of baseline, N.S.) but was accompanied by increases in both peak antegrade and retrograde flow velocity (161 +/- 75%, p < 0.001 and 413 +/- 377%, p < 0.001). A shift in the proportion of flow occurring in diastole (%DF) also was observed: baseline, 81 +/- 9%; HF, 82 +/- 6%; DCC assist, 121 +/- 16% (p < 0.001). Despite significant changes in coronary artery flow pattern resulting from DCC of the failing heart, total antegrade coronary flow was maintained. These findings suggest that myocardial perfusion is not compromised by DCC.