I do not practice in MO so this information is being provided for educational purposes only. You should probably consult a local attorney.
Generally, a MM action has three issues: (1) liability; (2) causation; and (3) damages. The question that needs to be answered to establish liability is, "did the doctor deviate from the applicable standard of care?" In plain language, did the doctor during the bypass do something or fail to to something that a reasonable physician would do under the same or similar circumstances. The same inquiry needs to be made for the subsequent hospitalizations. In most states, the law does not require a doctor to be right or provide a cure, it just requires a dr. to act in a reasonable manner.
If you are able to establish liability, the next inquiry is whether the negligence or malpractice caused the complained of injuries. The third inquiry is whether the injured person was damaged.
I am not licensed in MO, and can offer you only general legal advice. You have been given some general advice above regarding medical negligence cases. Let me apply those standards to the facts of your case to give you a factual evaluation now. (I also have a masters degree in physiology and worked for several years as a clinical manager in the hospital setting.) This is just my personal evaluation and you should remember that I am not telling you that you do not have a claim, because a MO lawyer may feel differently.
You have not indicated your father's age or whether he has other medical conditions that might be contributing factors. However, a delay in diagnosis of heart disease should be evaluated. You need to look back at your father's primary care records. Who was admitting him to the hospital for testing? Was he referred to a cardiologist and when? Did the delay worsen his disease such that he would be in much better cardiac health had the bypass ben performed earlier? (what is his ejection fraction now and what was it before the surgery? Ejection fraction is the amount of blood the heart puts out with each contraction. It should be above 50%.
Go with your father to his next visit to the doctor and speak with them about the medications that he is on. Many times, initially after a cardiac surgery, a patient will be prescribed beta blockers to protect the heart. It may be time now to talk to the doctor about whether that is still necessary.
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