Premature Atrial Contractions

ECG Features

Figure 1: ECG Strip[1]

A premature atrial contraction (PAC) or atrial premature contraction is "a premature beat arising from an ectopic focus within the atria."[2] Premature contractions are classified by their origin: atrial (PACs), junctional (PJCs), or ventricular (PVCs).

Table 1: ECG Characteristics[3]

Clinical Significance[4]

  • PACs are a normal electrophysiological phenomenon and do not usually require any treatment. Patients with PACs complain of palpitations and "a sense of the heart 'skipping a beat.' "
  • PACs mostly occur in healthy individuals without heart disease. Stress or stimulants such as caffeine, tobacco, and alcohol can increase the frequency of PACs. Although seldom, PACs can also be a sign of underlying heart condition in the atrium.
  • Although most PACs are benign, they may change into atrial flutter, atrial fibrillation, or supraventricular tachycardia.

ECM Features

Figure 2: ECM Analysis, Record 112[5][6]

ECM Examples

Figure 3: Record 113[5][6]

Figure 4: Record 202[5][6]

Figure 5: Record 213[5][6]

Additional Information


  1. Premature Atrial Complex [Online image]. (2013). Retrieved July 19, 2016, from
  2. Premature Atrial Complex (PAC). (n.d.). Retrieved July 27, 2016, from
  3. Premature Atrial Complex. (n.d.). Retrieved July 27, 2016, from
  4. Premature Atrial Contractions (PACs). (n.d.). Retrieved July 29, 2016, from
  5. MIT-BIH Arrhythmia Database. (1980). Retrieved June, 2016, from
  6. Goldberger AL, Amaral LAN, Glass L, Hausdorff JM, Ivanov PCh, Mark RG, Mietus JE, Moody GB, Peng C-K, Stanley HE. PhysioBank, PhysioToolkit, and PhysioNet: Components of a New Research Resource for Complex Physiologic Signals. Circulation101(23):e215-e220 [Circulation Electronic Pages;]; 2000 (June 13).