New high-grade atrioventricular block has reversible causes that a permanent device will not fix. The commonest are drugs that slow conduction — beta-blockers including eye drops, verapamil, diltiazem, digoxin and some antiarrhythmics — and hyperkalaemia. Inferior myocardial infarction can cause AV block that often resolves, and Lyme carditis, sarcoidosis and hypothyroidism are worth considering in the right patient.
Check these first, support with temporary pacing if needed, and reassess once the cause has been corrected.
- Review every medicine, including eye drops and recent dose changes.
- Check potassium and renal function urgently.
- Record a 12-lead ECG for inferior ischaemia.
- Consider Lyme serology and sarcoidosis in younger patients with unexplained block.
Why it matters
A permanent device is a lifelong commitment for a problem that is sometimes a medication list away from resolving.
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