Arrhythmias, APBs

Basics

Description

Atrial premature beats or complexes (APCs) are early atrial systoles identified on the EKG by early P waves.
The contour of the P wave may resemble sinus P waves, but it is usually different.
APCs mimic sinus P waves when they arise near the sinus node
When P waves occur very early, atrioventricular (AV) conduction may remain refractory, such that the impulse is not propagated to the ventricles (blocked APC).
Sometimes the P wave of an APC is difficult to identify because it falls in the T wave of the preceding QRS complex.
Synonym(s): Atrial premature complexes; Atrial premature contractions

Pregnancy may exacerbate frequency of APCs.
Changes in intravascular volume and subsequent atrial wall stress may trigger stretch-induced atrial arrhythmias.

Epidemiology

APCs increase with aging; in the elderly, APCs are ubiquitous.

Risk Factors

Structural heart disease with abnormalities of atrial structure or physiology, such as infiltrative diseases (amyloid), RV or LV failure, mitral or tricuspid insufficiency, following cardiac surgery, pericarditis

Etiology

Often, APCs have no particular cause and are a function of aging myocardium.
During times of stress and sympathetic stimulation
Hyperthyroidism
With MI in >50% of patients
In association with elevated atrial pressure and wall stress, for example LV failure or cor pulmonale
Alcohol, tobacco, and caffeine consumption
Drug toxicity, for example, digitalis toxicity

Diagnosis

Signs and symptoms:

Usually none, but occasionally can be felt as palpitations
They may presage sustained supraventricular tachycardia, atrial fibrillation, and atrial flutter.

Tests

EKG
Event recorder; especially useful to correlate symptoms with PACs
Holter monitor, useful to correlate symptoms and assess frequency of PACs
Telemetry in hospital

Lab

None per se, except to test for hyperthyroidism
ESR if myocarditis or pericarditis suspected

Differential Diagnosis

Junctional premature beats
Wandering atrial pacemaker

Treatment

Medication

First Line

If palpitations are a major complaint, β-blockade may be helpful.
β-Blockers:
- May decrease catecholamine stimulus, vigor of post-APC ventricular contraction, or timing of ventricular contraction, thereby improving symptoms
- In otherwise healthy patients, adverse drug effects may be worse than symptoms resulting from the arrhythmia.
Calcium channel blockers

Second Line
In highly symptomatic patients not responding to previously described medical therapy, antiarrhythmic drugs (class 1C if no structural heart disease, or class 3) can be tried, either alone or in combination with β-blockers.

Additional Treatment

General Measures
Usually no treatment is indicated or required.

Surgery

In selected patients, electrophysiologic mapping and catheter ablation of the PAC focus is possible.

In-Patient Considerations

Admission Criteria
Not applicable; patients are typically not admitted for APCs.

Ongoing Care

Follow-Up Recommendations

Patient Monitoring

Mostly never needed, follow clinical symptoms
If monitoring chosen, Holter EKG monitor to quantify daily APC frequency and Event Monitor/Holter EKG to correlate symptoms with rhythm.

Patient Education

APCs are common and benign.
Aggressive treatment with primary antiarrhythmic drugs may lead to morbidity and mortality in excess of that expected from APCs by themselves and can be avoided in most patients.
Rarely, antiarrhythmic drugs or catheter ablation is required.
Avoiding caffeine and other precipitating stimuli (alcohol, tobacco) may decrease APC frequency.
Activity is usually not restricted, but rather encouraged.

Prognosis

Normal; occasionally APCs may be a harbinger to atrial fibrillation, and may trigger reentrant supraventricular tachycardias.

Additional Reading

1
Braunwald E Heart Disease: A Textbook of Cardiovascular Medicine. Philadelphia: WB Saunders, 1997.

Codes

ICD9

427.61 Supraventricular premature beats

SNOMED

287057009 atrial premature complex (disorder)

Home

Erectile Dysfunction

Doctor123.org