Premature atrial complex

A premature atrial complex (PAC) is an extra beat that arrives early, originating from the atria. The P wave often has a different shape to normal. The QRS may be conducted normally (narrow), conducted with aberrancy (wide, often RBBB shaped), or non-conducted (absent). Nonconducted beats may be so early that the AV node is still refractory. There is usually a pause afterwards.

PACs are common and generally benign.

See also: Extra Beats

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ECG Library (27)

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In the ECGquest archives, this ECG has been tagged with: - Chest pain Dyspnoea 12-Lead Inverted T waves Normal Sinus Rhythm Premature atrial complex Acute right heart strain Pulmonary embolism Dr Smith's ECG Blog CC BY-NC
An elderly woman transferred to you for chest pain, shortness of breath, and positive troponin – does she need the cath lab now?

This ECG is from an elderly woman who presented with sudden onset shortness of breath after months of inactivity due to a back injury.

This ECG shows sinus tachycardia with large inverted T waves, consistent with right heart strain. The cause was a very large PE.

In the ECGquest archives, this ECG has been tagged with: - Chest pain Dyspnoea 12-Lead ST elevation in aVR Widespread ST depression Premature atrial complex Sinus tachycardia Aortic stenosis Dr Smith's ECG Blog CC BY-NC
An elderly man with sudden cardiogenic shock, diffuse ST depressions, and STE in aVR

This ECG is from a man in his 80s who presented with sudden onset chest pain and dyspnoea.

In the ECGquest archives, this ECG has been tagged with: - 12-Lead Nonspecific baseline artefact Premature atrial complex Aortic stenosis Dr Smith's ECG Blog CC BY-NC
An elderly man with sudden cardiogenic shock, diffuse ST depressions, and STE in aVR

This ECG is from a man in his 80s who presented with sudden onset chest pain and dyspnoea. This was the repeat ECG after he had an aortic valve replacement and CABG.

In the ECGquest archives, this ECG has been tagged with: - 12-Lead Grouped Normal P waves Bigeminy Premature atrial complex ECG Interpretation CC-BY-NC-SA
ECG Blog #140 – (PVC – Atrial Bigeminy – PAC – LAHB – RBBB – LPHB – Aberration).
In the ECGquest archives, this ECG has been tagged with: - Rhythm Strip Premature atrial complex LITFL
Aberrantly conducted PAC
In the ECGquest archives, this ECG has been tagged with: - 12-Lead Grouped Narrow QRS Premature atrial complex LITFL CC-BY-NC-SA
Frequent PACs and post-extrasystolic pauses