Can a patient have MI without ECG changes but troponin positive after 20 hours CK was also elevated initially?

Yes, a patient can have a myocardial infarction (MI) without electrocardiogram (ECG) changes but with elevated troponin levels after 20 hours and initially elevated creatine kinase (CK) levels. This is known as a "silent" or "electrocardiogram-negative" myocardial infarction.

Silent myocardial infarction is characterized by the presence of symptoms consistent with myocardial ischemia (chest pain, shortness of breath, etc.) but without the characteristic ST-segment elevation or depression on the ECG. Typically, ECG changes are seen within the first few hours of an MI, but some patients may not develop these changes, especially if the infarction is small or involves a different part of the heart.

In these cases, troponin levels can still be elevated as a result of myocardial injury. Troponin is a protein that is released into the bloodstream when heart muscle cells are damaged. It can be detected in the blood several hours after an MI and can remain elevated for up to 10 days.

CK is another enzyme that is released into the bloodstream after myocardial injury. CK levels typically peak within 24-48 hours after an MI and return to normal within 3-5 days.

The combination of elevated troponin levels and initially elevated CK levels, even in the absence of ECG changes, is strongly suggestive of myocardial infarction. Further testing, such as echocardiogram or cardiac MRI, may be necessary to confirm the diagnosis and assess the extent of the myocardial injury.