What causes premature ventricular contractions (PVCs)?

Causes of Premature Ventricular Contractions (PVCs)

Premature ventricular contractions are commonly caused by structural heart disease, but can also occur in healthy individuals due to various physiological and pathological factors.

Common Causes of PVCs

• Structural Heart Disease

  • Coronary artery disease and ischemic heart disease 1
  • Heart failure (both HFrEF and HFpEF) 1, 2
  • Hypertrophic cardiomyopathy (HCM) 1
  • Valvular heart disease 2
  • Previous myocardial infarction 1

• Electrolyte Abnormalities

  • Hypokalemia 2
  • Hypomagnesemia 2
  • Hypocalcemia 2

• Medications and Substances

  • Sympathomimetic agents 2, 3
  • Excessive caffeine consumption 2, 3
  • Alcohol 2, 3
  • Class I antiarrhythmic drugs (paradoxically) 4, 5

• Other Medical Conditions

  • Hyperthyroidism 2
  • Acute infections 2
  • Inflammatory conditions affecting the heart 2
  • Reperfusion after coronary intervention (reperfusion arrhythmias) 1

PVCs in Healthy Individuals

• PVCs are common and increase in frequency with age 1, 6
• Found in approximately 50% of all people on long-term monitoring 1, 6
• Prevalence of 0.6% in those <20 years of age and 2.7% in those >50 years of age on standard 12-lead ECGs 1, 6
• In young adults with high functional capacity, isolated PVCs are generally benign 6

Risk Factors for PVC-Induced Cardiomyopathy

• High PVC burden (>10-15% of total heartbeats, highest risk at >20-24%) 2, 7
• Short coupling interval of PVCs (<300 ms) 2, 8
• Wider QRS complexes (>160 ms) 2, 8
• PVCs originating from the epicardium or papillary muscles 8
• Interpolated PVCs (PVCs that don't reset the normal sinus rhythm) 8

Pathophysiological Mechanisms

• Triggered activity due to early or delayed afterdepolarizations 9
• Enhanced automaticity in ventricular tissue 9
• Reentry circuits in damaged myocardium 9
• Purkinje fiber injury leading to abnormal impulse formation 1
• Myocardial stretch in dilated ventricles 7

Clinical Significance

• Most PVCs in healthy individuals are benign 6, 10
• Frequent PVCs (>10,000-20,000/day or >10-15% of total beats) can lead to PVC-induced cardiomyopathy 1, 7, 10
• PVCs may be a marker of underlying structural heart disease, especially in older patients 1, 11
• In acute coronary syndromes, PVCs may indicate incomplete revascularization or recurrence of acute ischemia 1
• PVCs can trigger more serious ventricular arrhythmias in susceptible individuals 1

Special Considerations

• PVCs in athletes are uncommon (<1% on 12-lead ECGs) but require evaluation when present 6
• In patients with idiopathic ventricular fibrillation, PVCs from injured Purkinje fibers can act as triggers 1
• Multifocal PVCs may indicate higher cardiovascular risk even in young adults 6
• PVCs that worsen with exercise may indicate underlying pathology, while those that suppress with exercise are generally benign 6

Understanding the specific cause of PVCs is essential for appropriate risk stratification and management decisions, particularly in distinguishing benign from potentially harmful PVCs.