From the Guidelines
Premature Ventricular Contractions (PVCs) and Premature Atrial Contractions (PACs) can be differentiated based on their origin and characteristics on an electrocardiogram (ECG).
Key Differentiating Features
- Origin: PVCs originate from the ventricles, whereas PACs originate from the atria 1.
- ECG Characteristics: PVCs are characterized by a wide QRS complex (>120 ms) and a premature beat that is not preceded by a P wave, whereas PACs are characterized by a narrow QRS complex and a premature beat that is preceded by a P wave with an abnormal axis 1.
Evaluation and Diagnosis
- ECG and Holter Monitoring: A 12-lead ECG and 24-hour Holter monitoring can help diagnose and differentiate between PVCs and PACs 1.
- Exercise Stress Test: An exercise stress test can help evaluate the response of PVCs to exercise and determine if they are benign or associated with underlying heart disease 1.
- Echocardiogram: An echocardiogram can help rule out underlying structural heart disease, such as cardiomyopathy or coronary artery disease 1.
Clinical Significance
- PVCs: Frequent PVCs (>2000 per 24 hours) are associated with an increased risk of underlying cardiac disease and cardiovascular mortality 1.
- PACs: PACs are generally benign, but can be associated with underlying cardiac disease, such as atrial fibrillation or heart failure 1. In clinical practice, it is essential to evaluate patients with PVCs or PACs to determine their underlying cause and risk of cardiovascular disease, and to provide appropriate management and treatment 1.
From the Research
Differentiating between Premature Ventricular Contractions (PVCs) and Premature Atrial Contractions (PACs)
To differentiate between PVCs and PACs, it is essential to understand the characteristics of each condition.
- PVCs refer to electrical activity arising from the ventricles, resulting in ventricular contraction independent of the native rhythm 2.
- PACs, on the other hand, are characterized by electrical activity arising from the atria, leading to atrial contraction independent of the native rhythm.
Key Differences
- The origin of the electrical activity: PVCs originate from the ventricles, while PACs originate from the atria.
- The presentation of symptoms: PVCs may present with symptoms such as palpitations, lightheadedness, chest discomfort, or the sensation of skipped beats, while PACs may present with similar symptoms, but the underlying cause and mechanism are different 3.
Diagnostic Techniques
- Electrocardiogram (ECG) beat classification is essential for timely diagnosis of serious heart disorders, including PVCs and PACs 4.
- Mode entropy-based techniques can be used to classify normal sinus rhythm, APC, and PVC, providing a rational and accurate method for detection 4.
- Four-Dimensional Automated Left Atrial Quantification (4D Auto LAQ) tool can be used to quantify left atrial function and determine alterations in patients with PVCs 5.