Approach Considerations
In general, no treatment is indicated for asymptomatic isolated first-degree atrioventricular (AV) heart block.
For patients with marked first-degree AV block (PR interval > 300 msec), however, several uncontrolled trials have demonstrated symptomatic improvement with placement of a dual-chamber pacemaker, though there is little evidence suggesting improved survival. [3] in patients with severe bradycardia or those with the possibility of progression to higher-degree AV block, medications (eg, atropine, isoproterenol) can be used in anticipation of insertion of a cardiac pacemaker.
Any associated condition (eg, myocardial infarction [MI], digitalis intoxication) should be treated appropriately. Significant electrolyte abnormalities should be corrected.
In patients with symptomatic first-degree AV block, discontinue medications with potential for AV block, if possible. Electrophysiology consultation may be indicated for patients with first-degree AV block and symptoms of syncope or heart failure.
In general, hospitalization specifically for first-degree AV block is not indicated. However, admission may be indicated for associated conditions (eg, MI). Patients with a marked first-degree AV block can present with symptoms similar to the pacemaker syndrome. [3] In these individuals, admission may be indicated.
Pacemaker Implantation
According to guidelines from the American College of Cardiology (ACC), the American Heart Association (AHA), and the Heart Rhythm Society (HRS), permanent pacemaker implantation is reasonable for first-degree AV block with symptoms similar to those of pacemaker syndrome or hemodynamic compromise (class IIa recommendation; level of evidence, B). [29] Additional ACC/AHA/HRS recommendations have been formulated for other patients with first-degree AV block, as follows.
Patients with first-degree AV block, with or without symptoms, may be considered for permanent pacemaker implantation if the block occurs in the setting of neuromuscular diseases such as myotonic muscular dystrophy, Erb dystrophy (limb-girdle muscular dystrophy), or peroneal muscular atrophy, because these patients may experience unpredictable progression of AV conduction disease (class IIb recommendation, level of evidence, B).
Permanent pacemaker implantation is not indicated for asymptomatic first-degree AV block (class III recommendation; level of evidence, B).
Long-Term Monitoring
In the absence of a disease process that requires admission, patients with first-degree AV block may be safely discharged and receive follow-up on an outpatient basis. Patients should get serial follow-up electrocardiograms (ECGs) to evaluate for progression to a higher-grade AV block.
Patients with first-degree AV block started on atrioventricular node (AVN)-blocking drugs should be monitored to make sure that higher-grade AV block does not develop. Patients with first-degree AV block and coexistent bundle-branch block should be closely observed.
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First-Degree Atrioventricular Block. The PR interval is 0.24 seconds (240 ms) in a patient with asymptomatic first-degree atrioventricular block.
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First-Degree Atrioventricular Block. 12-Lead electrocardiogram from a patient with first-degree heart block.
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First-Degree Atrioventricular Block. 12-Lead electrocardiogram from a patient with first-degree heart block.
