What are the differences in characteristics, clinical implications, and management between premature ventricular contractions (PVCs) and a gallop rhythm?

From the Guidelines

Premature ventricular contractions (PVCs) and gallop rhythms are distinct cardiac findings with different origins, characteristics, and clinical implications, and the most recent evidence suggests that PVCs are associated with increased cardiovascular risk and mortality, while gallop rhythms are abnormal heart sounds reflecting hemodynamic or structural cardiac abnormalities. PVCs are electrical abnormalities characterized by early beats originating from the ventricles, producing a premature, wide QRS complex on ECG followed by a compensatory pause, as noted in the 2017 AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death 1. They often cause symptoms like palpitations, skipped beats, or dizziness. PVCs may be benign in healthy hearts but can indicate underlying structural heart disease when frequent (>10-15% of beats) or complex.

Characteristics of PVCs and Gallop Rhythms

• PVCs are electrical abnormalities with a premature, wide QRS complex on ECG, while gallop rhythms are auscultatory findings representing extra heart sounds (S3 or S4) that create a cadence resembling a galloping horse.
• An S3 gallop occurs in early diastole, often indicating volume overload and heart failure, while an S4 gallop in late diastole suggests decreased ventricular compliance from conditions like hypertension or aortic stenosis.
• Management of PVCs depends on symptom burden and underlying cardiac status, ranging from reassurance for asymptomatic patients with normal hearts to beta-blockers, calcium channel blockers, or antiarrhythmics like amiodarone for symptomatic cases, as recommended in the 2015 ESC guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death 1.

Clinical Implications and Management

• Catheter ablation may be considered for medication-resistant, highly symptomatic PVCs, particularly in patients with PVC-induced cardiomyopathy, as suggested by the 2017 AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death 1.
• Management of gallop rhythms targets the underlying cause, typically focusing on heart failure treatment with diuretics, ACE inhibitors, beta-blockers, and lifestyle modifications.
• Unlike PVCs, gallop rhythms are not arrhythmias but rather abnormal heart sounds reflecting hemodynamic or structural cardiac abnormalities.
• The detection of PVCs, particularly if multifocal and frequent, is generally considered a risk factor for adverse cardiovascular outcomes, and such patients are generally evaluated to ensure they do not have underlying conditions that warrant further treatment to reduce risk, as noted in the 2017 AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death 1.

From the Research

Characteristics of PVCs and Gallop Rhythm

• Premature ventricular contractions (PVCs) are characterized by an early electrical impulse originating in the ventricles, disrupting the normal heart rhythm 2.
• A gallop rhythm, on the other hand, is a type of arrhythmia characterized by a third heart sound (S3) or a fourth heart sound (S4), which can be distinguished from PVCs using the compensatory pause that follows a PVC 2.
• PVCs can provide clues to the physical or electrocardiographic diagnosis through the associated compensatory pause, the break in the regularity of the rhythm, or the morphology of the PVC itself 2.

Clinical Implications

• PVCs can be useful in distinguishing an S3 gallop from an S4 gallop, and the compensatory pause that follows a PVC may allow normal conduction of the next QRS complex in a patient with a rate-dependent intraventricular conduction defect 2.
• A gallop rhythm can be indicative of heart failure or other cardiac conditions, and its presence can guide further diagnosis and management 3.
• The presence of PVCs or a gallop rhythm can have significant implications for patient management, including the need for further diagnostic testing or treatment with medications such as beta-blockers or angiotensin-converting enzyme (ACE) inhibitors 3.

Management

• The management of PVCs and gallop rhythm depends on the underlying cause and the patient's clinical presentation 3.
• Beta-blockers and ACE inhibitors are commonly used in the management of heart failure, and can be effective in reducing mortality and hospital readmissions 3.
• Combining beta-blockers and ACE inhibitors, or integrating them with newer agents, can provide an additive benefit and improve long-term survival and reduce heart failure-related hospitalizations 3.