Give a step-by-step guide to review ECG or share any more details which can

Clinical answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 5 May 2026Updated: 5 May 2026 Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

Step-by-step guide for reviewing an electrocardiogram (ECG) in patients taking antipsychotic medication:

  • Obtain baseline ECG before starting antipsychotic treatment, especially if the drug's Summary of Product Characteristics (SPC) specifies it, or if the patient has cardiovascular risk factors such as hypertension, personal or family history of cardiovascular disease, or is inpatient ,.
  • Perform regular ECG monitoring for antipsychotics known to significantly prolong the QT interval, particularly haloperidol, pimozide, and sertindole, with annual ECGs being mandatory for these drugs ,.
  • Monitor ECG after dose changes or if new medications that may prolong QT interval are added .
  • Measure and interpret the QT interval: a QT corrected interval (QTc) greater than 450 milliseconds warrants concern, and a QTc over 500 milliseconds requires urgent specialist psychiatric advice ,.
  • Evaluate for ECG features that increase arrhythmia risk, such as prolonged QT interval and other conduction abnormalities; seek specialist advice if uncertain .
  • Record and send ECG findings to the patient's care coordinator or psychiatrist as part of the annual physical health review .

Additional clinical information to assist interpretation:

  • Note drug-specific risks: haloperidol, pimozide, and sertindole carry highest QT prolongation risk; other antipsychotics have variable effects on ECG ,.
  • Consider patient-specific factors including electrolyte imbalances, concomitant medications that prolong QT, and smoking status affecting drug metabolism and cardiac risk ,.
  • Recognize that clozapine may cause ECG changes such as ST segment depression and T wave inversion, which may normalize after stopping, but may indicate myocarditis; signs of myocarditis include persistent tachycardia, palpitations, arrhythmias, chest pain, and symptoms mimicking myocardial infarction—these warrant further cardiac evaluation ,,,.
  • Be aware of symptoms potentially related to cardiac effects of antipsychotics, including palpitations, unexplained fatigue, dyspnoea, or syncope that may suggest arrhythmia or myocarditis ,,,,,.
  • Gather history of substance use (alcohol, tobacco, other drugs) as these can affect cardiac risk and drug metabolism ,.
  • Obtain and consider other baseline and ongoing physical health measures such as electrolytes, renal function, and cardiovascular risk factors to contextualize ECG findings ,.

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Educational content only. Always verify information and use clinical judgement.