SAN FRANCISCO, CA — Knowing the number of hourly premature atrial contractions (PACs) a patient has is as good as the Framingham atrial fibrillation (AF) risk algorithm in predicting five- to 15-year ... What are premature atrial contractions? Premature atrial contractions (PACs) are extra heartbeats that start in the upper chambers (or atria) of your heart.

Understanding the Context

Premature atrial contractions (PACs) are usually harmless and not a cause for concern. People with PACs may feel skipped or extra heartbeats, but often there are no symptoms. PACs are common and can be caused by heart disease, stress, or certain medications. A premature atrial complex (PAC) is a premature beat arising from ectopic pacemaking tissue within the atria.

Key Insights

There is an abnormal P wave, usually followed by a normal QRS complex. Premature beats that start in your heart’s upper chambers are premature atrial contractions, or PACs. Those that start in the lower chambers are premature ventricular contractions, or PVCs. A PAC, or premature atrial contraction, is an extra heartbeat that starts in the upper chambers of your heart slightly earlier than it should. It feels like a skipped beat, a flutter, or a brief thump in your chest.

Final Thoughts

PACs are extremely common and, in most cases, completely harmless. A premature atrial contraction (PAC), also known as atrial premature complex (APC) or atrial premature beat (APB), is a common arrhythmia characterized by premature heartbeats originating in the atria. Premature atrial contractions (PACs) can be seen in a broad spectrum of patients with and without heart disease and are often considered benign clinical phenomena. Recent studies have, however, shown an association between PACs and new-onset atrial fibrillation (AF), stroke, and all-cause mortality. 1 ,2