How can frequent PVCs affect overall rhythm on ECG?

• A. They cannot affect rhythm
• B. They contribute to sinus tachycardia
• C. They can trigger runs of VT and disrupt regular rhythm, potentially contributing to cardiomyopathy if very frequent
• D. They cause immediate ventricular fibrillation

Answer: (C)

Frequent PVCs are ventricular ectopic beats that interrupt the normal sinus rhythm. When they’re infrequent, the rhythm stays mostly regular with occasional early, wide QRS complexes. But as the PVC burden rises, these ectopic beats can occur in rapid succession or in runs, including patterns like couplets or triplets, which can trigger ventricular tachycardia and disrupt the regular rhythm. Over time, a very high frequency of PVCs can lead to tachycardia-induced cardiomyopathy due to the sustained abnormal rhythm and impaired ventricular filling and output. So the best description is that frequent PVCs can trigger runs of VT and disrupt regular rhythm, potentially contributing to cardiomyopathy if very frequent.