**Core Concept**
Perioperative Myocardial Infarction (PEM) is a serious complication that can occur during or after surgery. The diagnosis of PEM is often based on clinical presentation, electrocardiogram (ECG) changes, and biomarkers such as troponin levels. A normal troponin level is generally considered a strong indicator against PEM.

**Why the Correct Answer is Right**
A normal troponin level indicates that there is no detectable cardiac muscle damage, which is a key criterion for diagnosing myocardial infarction. Troponin is a highly sensitive and specific biomarker for cardiac damage, and a normal level suggests that the cardiac muscle is not experiencing ischemia or infarction. This, in turn, makes PEM less likely.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided.
* **Option B:** This option is not provided.
* **Option C:** This option is not provided.
* **Option D:** This option is not provided.

**Clinical Pearl / High-Yield Fact**
A normal preoperative ECG and troponin level can provide reassurance against PEM, but these tests are not foolproof. Clinical judgment and ongoing monitoring remain essential in the perioperative period.

**Correct Answer: D. Normal troponin level rules out PEM**