Search
premature atrial complex (PAC, atrial premature contraction, APC)
Premature Atrial Complex (PAC) are atrial depolarizations* that occur prior to arrival of the impulse originating in the sinus node. Most commonly they result from abnormal automaticity, but may occur as a result of intra-atrial re-entry.
* with resultant premature atrial contraction
Etiology:
1) infection
2) inflammation
3) myocardial ischemia
4) drug toxicity
5) catecholamine excess
6) electrolyte imbalance
7) tobacco
8) alcohol
9) caffeine
Clinical manifestations:
1) patients may be asymptomatic
2) feeling of skipped beats
Special laboratory:
- electrocardiogram:
1) p-wave appears earlier than expected & with different morphology (contour & axis) than the sinus-initiated p-wave
2) PR interval following the PAC may be slightly prolonged
3) generally a compensatory pause between PAC & next sinus- initiated p-wave
Management:
1) asymptomatic patients require no therapy
2) symptomatic individuals
a) therapy directed towards the underlying preciptiating factor(s)
1] offending drugs
2] electrolyte abnormalities
b) beta-adrenergic receptor antagonists
c) Ca+2-channel blockers
General
premature electrocardiography complex
References
- Manual of Medical Therapeutics, 28th ed, Ewald &
McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 140
- Conen D, Adam M, Roche F et al
Premature atrial contractions in the general population:
frequency and risk factors.
Circulation. 2012 Nov 6;126(19):2302-8.
PMID: 23048073