Which statement best describes the appearance and risk of a premature ventricular contraction (PVC) on ECG?

• A. An early, wide QRS complex not preceded by a P wave
• B. A late, narrow QRS complex preceded by a P wave
• C. A normal QRS with a P wave not matching
• D. A QRS that is preceded by a U wave

Answer: (A)

Premature ventricular contractions come from a ventricular focus, so the beat fires earlier than expected and activates the ventricles through the muscle instead of the usual His-Purkinje pathway. That ventricle-origin impulse produces a wide, bizarrely shaped QRS complex and, because the impulse doesn’t start in the atria, there is no preceding P wave for that beat. You’ll often see a compensatory pause after the PVC as the heart resets its rhythm.

In terms of risk, a single PVC in a healthy person is typically harmless. The concern rises with higher frequency or certain patterns—frequent PVCs, pairs, runs, or multifocal PVCs, especially in someone with heart disease—because the overall PVC burden can predispose to more serious ventricular arrhythmias or even contribute to cardiomyopathy. The other descriptions don’t fit a PVC: a late, narrow QRS with a preceding P wave is more like a normal atrial/ventricular conduction pattern; a normal QRS with a P wave not matching suggests atrial ectopy or conduction issues rather than ventricular origin; a QRS preceded by a U wave is not characteristic of a PVC.