**Core Concept**
Rescue PCI (percutaneous coronary intervention) is indicated in patients with acute myocardial infarction who fail to respond to thrombolysis, particularly when there is persistent ST-segment elevation despite treatment. This decision is based on the risk of ongoing myocardial ischemia and the potential for significant infarct size and complications.

**Why the Correct Answer is Right**
According to current guidelines (e.g., ACC/AHA and ESC), rescue PCI is recommended for patients with persistent ST elevation >90 minutes after thrombolysis. This threshold reflects the time at which reperfusion failure is likely, and the risk of irreversible myocardial damage increases significantly. After 90 minutes, the likelihood of effective reperfusion via thrombolysis diminishes, making PCI the preferred intervention to restore blood flow and limit infarct size.

**Why Each Wrong Option is Incorrect**
Option A: ST elevation >60 minutes is too early to consider rescue PCI; 60 minutes is still within the window where thrombolysis may be effective, and earlier intervention is preferred.
Option B: >30 minutes is insufficient—this is too short a time to justify rescue PCI; early reperfusion is still possible with thrombolysis.
Option D: >120 minutes is beyond the typical window for rescue PCI; by this time, the infarct is likely extensive, and outcomes are poor, making PCI less effective and more risky.

**Clinical Pearl / High-Yield Fact**
A key high-yield point: **Persistent ST elevation >90 minutes after thrombolysis is the threshold for rescue PCI**—this is a critical time-based decision to prevent further myocardial injury. Always remember that time is muscle in acute MI.

✓ Correct Answer: C. Persistent Chest pain with ST elevation >90 min after thrombolysis