Atrial Premature Complexes and Atrial Tachycardia
Basic Information 
Definition
• Atrial premature complex (APC): A premature depolarization that originates from the atrial myocardium, resulting in a P′ wave on the surface electrocardiogram (ECG) (Figure 1).
• Atrial tachycardia (AT): Three or more consecutive atrial premature beats, usually with regular P′P′ intervals.
• Depending on their prematurity, the premature beats may or may not be conducted to the ventricles.
Clinical Presentation
History, Chief Complaint
• Usually no complaints; incidental finding during auscultation or ECG
• Occasionally, poor performance
• Complaints related to underlying disease (eg, respiratory or gastrointestinal disease, atrial dilation caused by mitral regurgitation)
• Previous episodes of atrial fibrillation (paroxysmal AF or successfully converted AF)
Physical Exam Findings
• Pulse deficits or weak pulses may be palpated.
• Signs of underlying disease that produces hypoxia, electrolyte imbalance, atrial dilation (eg, heart murmur, heart failure)
Etiology and Pathophysiology
• Electrolyte and metabolic disturbances
• Drug administration (halothane, dobutamine)
• Iatrogenic during cardiac catheterization
• An electrical impulse is generated in the atrial myocardium and depolarizes both atria.
• Hemodynamic effects of isolated APCs, especially nonconducted APCs, are minimal. Frequent occurrence of conducted APCs, bouts of AT, or sustained AT reduce cardiac output and affect performance.
• APCs may increase, decrease, or disappear altogether during exercise.
