An 84-yeаr-оld wоmаn оn metoprolol succinаte 50 mg daily for hypertension is brought to the emergency department by her daughter, who reports 2 days of progressive confusion and decreased oral intake. Her baseline BP at her last office visit was 145/85 mmHg with a HR of 68 bpm. Current vital signs: BP 100/60 mmHg, HR 74 bpm, RR 22, SpO2 95% on room air, temperature 38.4°C. She is oriented only to person and has dry mucous membranes. The APRN notes that the heart rate of 74 bpm appears reassuring. Why is this finding potentially misleading in this clinical context?