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The limited information provided is not sufficient enough to arrive at an appropriate conclusion...
Probably, she had sustained a Right ventricular infarction? / right heart failure
– in which case the fluid overload may actually help to maintain the heart function and she is likely to come around well...
Fluid in the lungs is from left heart failure – infarction / muscle damage from blocked coronary arteries / and could improve after the bypass surgery
The treating doctor alone can suggest based on his assessment of the situation.
Wishing speedy recovery