## Clinical Context This patient has **first-degree AV block** (PR interval >200 ms) in the setting of acute inferior MI. He is haemodynamically stable with no symptoms. ## Management Approach for First-Degree AV Block in Acute MI **Key Point:** First-degree AV block in acute MI is usually benign and does not require immediate intervention if the patient is stable. ### Rationale for Conservative Management | Feature | Finding | Significance | |---------|---------|---------------| | AV block type | First-degree | Conduction delay only; no dropped beats | | Haemodynamic status | Stable | HR 52, BP 118/76; no hypotension | | Symptoms | Absent | No chest pain, dyspnoea, syncope, or presyncope | | QRS duration | Normal | Narrow complex; block is at AV node level | | MI location | Inferior | AV nodal ischaemia is common but usually transient | **High-Yield:** In acute inferior MI, first-degree AV block is often caused by increased vagal tone and AV nodal ischaemia. Most resolve spontaneously within hours to days without intervention. ### When Intervention Is Needed Pacemaker insertion (temporary or permanent) is indicated only if: 1. **Symptomatic bradycardia** (hypotension, altered mental status, cardiogenic shock) 2. **Progression to higher-degree block** (second-degree Mobitz II or third-degree) 3. **Haemodynamic compromise** develops **Clinical Pearl:** Atropine is reserved for symptomatic bradycardia or progression to second- or third-degree block. It is not indicated in asymptomatic first-degree block. ### Recommended Next Step **Continuous cardiac monitoring and observation** allows detection of: - Progression to higher-degree block - Development of haemodynamic compromise - Spontaneous resolution (expected in most inferior MI cases) This approach is consistent with ACC/AHA guidelines for acute MI management.
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