Arrhythmias are common during acute coronary syndrome. Their significance and treatment depend on timing, rhythm and haemodynamic effects.
General measures and ventricular arrhythmias
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Many arrhythmias are transient and have no haemodynamic or prognostic importance. Adequate pain relief, rest and correction of hypokalaemia reduce arrhythmia risk.
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Ventricular fibrillation occurs in 5%–10% of patients who reach hospital and is thought to be the major cause of death before medical attention.
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Prompt defibrillation restores sinus rhythm and is life-saving. Patients promptly and successfully resuscitated from ventricular fibrillation within the first 48 hours have the same prognosis as patients without ventricular fibrillation.
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Ventricular arrhythmias during convalescence may indicate poor ventricular function and herald sudden death. Selected patients may benefit from electrophysiological testing and specific anti-arrhythmic therapy, including ICDs.
Atrial fibrillation
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Atrial fibrillation is common, frequently transient and usually does not require emergency treatment.
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A rapid ventricular rate causing hypotension or circulatory collapse requires prompt cardioversion.
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In other circumstances, digoxin or a beta-blocker is usually the treatment of choice.
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Atrial fibrillation may indicate impending or established left ventricular failure. Treatment may be ineffective unless accompanying heart failure is recognised and treated.