Summary
Supraventricular premature beats (SPBs) are atrial contractions triggered by ectopic foci rather than the sinoatrial node. They arise within the atria (atrial premature beats) or, through retrograde conduction, in the atrioventricular node (junctional premature beats). Premature beats may be found in healthy individuals as well as in individuals with underlying heart disease. Certain triggers (e.g., alcohol, smoking, or electrolyte imbalances) may contribute to the occurrence of SPBs. SPBs can be identified on ECG by QRS complexes preceded by absent or abnormal P waves and an altered PR interval. Although SPBs do not significantly impair cardiac output on their own, they may predispose to more severe forms of arrhythmia such as atrial fibrillation. Treatment is not required unless patients exhibit severe symptoms (e.g., tachycardia).
Etiology
Atrial contractions are triggered by ectopic foci (not the sinoatrial node), which arise from within the atria (atrial premature beats) or, through retrograde conduction, in the atrioventricular node (junctional premature beats).
- Idiopathic
- Potential triggers: smoking, alcohol, coffee [1]
- Cardiovascular disease or electrolyte imbalances (e.g., hypokalemia)
SPBs are very common in the general population. In one study, 99% of participants had at least 1 premature atrial contraction during 24-hour Holter monitoring. [2]
Classification
- Atrial premature beat: : extrasystole that originates in the atrial myocardium and occurs prior to the expected QRS complex
- Junctional premature beat: premature beat that originates between the atria and ventricles and occurs prior to the expected QRS complex
Clinical features
- Usually asymptomatic
- Irregular pulse
- Palpitations
Diagnosis
General principles [3]
- 12-lead ECG may incidentally identify SPBs.
- Ambulatory ECG monitoring (e.g., Holter monitoring) is most reliable for assessing SPB burden.
- Echocardiography may be considered to rule out underlying heart disease, especially in symptomatic patients.
Frequent SPBs are associated with the future development of atrial fibrillation and stroke. [4]
ECG [5]
Atrial premature beats
- P-wave abnormalities or absent P waves
- Altered PR interval in the premature beats (compared to the normal beats)
- QRS complex may be normal, aberrant (widened), or absent.
- No full compensatory pause [6]
- Atrial bigeminy: atrial premature beat that couples to a normal beat coming from the sinus node [5]
- Atrial trigeminy: atrial premature beat that couples to two normal beats coming from the sinus node
Junctional premature beats
- Retrograde P wave
- Narrow QRS complex or widened QRS complex if aberrant ventricular conduction is present [5]
- Junctional bigeminy: junctional premature beat that couples to a normal beat coming from the sinus node [5]
- Junctional trigeminy: junctional premature beat that couples to two normal beats coming from the sinus node [5]
Specialized testing [3]
Indications [3]
- Symptomatic SPBs
- Frequent SPBs [3][7]
SPBs are a common incidental finding on routine ECGs. No workup is required in asymptomatic patients without frequent SPBs.
Modalities [3]
-
Ambulatory ECG monitoring: e.g., 24- or 48-hour Holter monitoring
- Determines the frequency and overall burden of SPBs
- Can help match symptoms to the occurrence of SPBs
- May allow for identification of concomitant arrhythmias (e.g., atrial fibrillation)
- Cardiac imaging: to rule out structural heart disease and evaluate cardiac structure and function
Treatment
- Treatment is not required in asymptomatic individuals without underlying structural heart defects. [7][8]
- Underlying conditions, e.g., electrolyte imbalances, should be treated.
- Anticoagulation may be considered in patients with high SPB burden to reduce the risk of stroke. [3][7]
- ASCVD risk assessment in patients with risk factors, and management of ASCVD [9]
- Symptomatic patients
- Advise patients to reduce potential triggers like caffeine, alcohol, stress, and smoking. [8]
- Consider beta blockers or catheter ablation in patients with persistent symptoms. [9]
Prognosis
- The impact of the presence of asymptomatic SPBs is not fully elucidated. [7]
- Increased risk of stroke and all-cause mortality
- Increased risk of atrial fibrillation and/or atrial flutter [7][10]