**Core Concept**
Routine second-look endoscopy is a procedure used to evaluate the success of initial endoscopic treatment in patients with non-variceal upper gastrointestinal bleeding (NVUGIB). It aims to identify any remaining bleeding sites or complications that may require further intervention.

**Why the Correct Answer is Right**
Patients treated with epinephrine injection alone are at higher risk of bleeding recurrence due to the temporary nature of epinephrine's hemostatic effect. Epinephrine causes vasoconstriction, which temporarily controls bleeding, but it does not address the underlying cause of the bleeding. A second-look endoscopy is recommended in these patients to assess the efficacy of the initial treatment and to identify any remaining bleeding sites that may require additional therapy, such as clips or thermal coagulation.

**Why Each Wrong Option is Incorrect**
**Option A:** The Rockall score is a predictive model used to estimate the risk of rebleeding and mortality in patients with NVUGIB. While a Rockall score of 2 indicates a moderate risk, it does not specifically indicate the need for a second-look endoscopy.
**Option C:** Cardiac disease is a comorbidity that may increase the risk of mortality in patients with NVUGIB, but it is not a direct indication for a second-look endoscopy.
**Option D:** Renal disease is also a comorbidity that may affect the patient's overall health, but it is not a specific indication for a second-look endoscopy in the setting of NVUGIB.

**Clinical Pearl / High-Yield Fact**
When managing NVUGIB, it's essential to consider the type of treatment used initially, as well as the patient's underlying comorbidities and risk factors for rebleeding. A second-look endoscopy should be performed in patients treated with epinephrine injection alone to ensure the best possible outcomes and to minimize the risk of bleeding recurrence.

**✓ Correct Answer: B. Treated with epinephrine injection alone**