Which assessment finding would be of most concern for a nurse monitoring a client after a myocardial infarction?

Decreased urinary output is a significant finding to monitor in a patient post-myocardial infarction because it can indicate kidney perfusion issues and potential heart failure. After a myocardial infarction, the heart's ability to pump blood effectively can be compromised. This reduced cardiac output may lead to diminished blood flow to the kidneys, resulting in decreased urine production. Urinary output is a vital sign of renal function and can serve as an indicator of the patient’s hemodynamic status.

In addition, decreased urine output may also signify fluid overload or worsening heart failure, where the body is retaining fluid due to the heart's inability to effectively circulate it. Close monitoring of renal function is critical in this context, as it could prompt timely interventions to prevent further complications, such as acute kidney injury or worsening heart failure.

While elevated blood pressure, increased heart rate, and a normal respiratory rate may also be relevant findings, they are not as immediately alarming as decreased urinary output, which points to potential systemic complications.