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5.2 Pacing for atrioventricular block

5.2.1 Indications for pacing Treatment of AVB aims at ameliorating symptoms and preventing syncope and sudden cardiac death (SCD). First-degree AVB is usually asymptomatic. Syncope and dizziness are mainly observed in highdegree and complete AVB, especially in the paroxysmal forms. HF symptoms are more common in chronic AVB with permanent bradycardia, but can also be observed in first-degree AVB with a very prolonged PR interval. Given the commonly advanced age at onset of AVB, manifestations of fatigue, exertional intolerance, and HF are sometimes underestimated. Deterioration of cognitive functions is often only speculative so that the possibilities of improvement after implantation of a pacemaker are unpredictable and unlikely. Death in patients with untreated AVB is due not only to HF secondary to low cardiac output, but also to SCD caused by prolonged asystole or bradycardia-triggered ventricular tachyarrhythmia. Although RCTs of pacing in AVB have not been performed, it is clear from several observational studies that pacing prevents recurrence of syncope and improves survival.1012

5.2.1.1 First-degree atrioventricular block Usually the prognosis is good in the absence of structural heart disease, and progression to high-degree block is uncommon.175 The indication for pacing relies on an established correlation between symptoms and AVB. There is weak evidence to show that marked PR prolongation (i.e. >_300 ms), particularly when it persists or is prolonged during exercise, can lead to symptoms similar to pacemaker syndrome and/or that these can improve with pacing.176 Symptom correlation is crucial, although it may be difficult if these are nonspecific and subtle. In the absence of a clear correlation, a pacemaker is generally not indicated.

5.2.1.2 Second-degree type I atrioventricular block (Mobitz type I or Wenckebach) In addition to the presence or absence of symptoms, the risk of progression to higher degrees of AVB should be considered. Supranodal block has a benign course, and the risk of progression to type II or a higher degree of AV block is low. Small, retrospective studies have suggested that, over the long term, this type of AVB carries a higher risk of death in patients aged >_45 years in the absence of pacemaker implantation.177,178 Infranodal block (rare in this form of block) carries a high risk of progression to complete heart block, syncope, and sudden death, and warrants pacing even in the absence of symptoms.179,180

5.2.1.3 Second-degree Mobitz type II, 2:1, and advanced atrioventricular block (also named high-grade atrioventricular block, where the P:QRS ratio is 3:1 or higher), third-degree atrioventricular block In the absence of a reversible cause, due to the risk of occurrence of severe symptoms and/or possible progression towards a more severe or complete AVB, patients should receive a pacemaker even in the absence of symptoms. In asymptomatic patients in whom a 2:1 AVB is found incidentally, the decision for implantation should be made on a case by case basis including distinction between nodal and infranodal AVB. This distinction may be based on observations such as PR or PP interval prolongation before AVB, the effect of exercise on AV conduction, and an EPS.

5.2.1.4 Paroxysmal atrioventricular block Because of the risk of syncope and SCD and of the potential progression to permanent AVB, the indications for pacing are the same for paroxysmal as for permanent AVB. It is crucial to rule out a reversible cause and to recognize the reflex forms of AVB, which may not need pacing. Documentation of infranodal block by EPS or the documentation of initiation of the block by atrial or ventricular premature beats, or increased heart rate (tachy-dependent AVB) or decreased heart

Recommendations for pacing in sinus node dysfunction

Recommendations Classa Levelb

In patients with SND and a DDD pacemaker, minimization of unnecessary ventricular pacing through programming is recommended.144,151,159,164,166169 I A Pacing is indicated in SND when symptoms can clearly be attributed to bradyarrhythmias.14,128131 I B Pacing is indicated in symptomatic patients with the bradycardiatachycardia form of SND in order to correct bradyarrhythmias and enable pharmacological treatment, unless ablation of the tachyarrhythmia is preferred.17,20,21,136138,170,171 I B In patients who present chronotropic incompetence and have clear symptoms during exercise, DDD with rate-responsive pacing should be considered.172,173 IIa B AF ablation should be considered as a strategy to avoid pacemaker implantation in patients with AF-related bradycardia or symptomatic preautomaticity pauses, after AF conversion, taking into account the clinical situation.136139,174 IIa C In patients with the bradycardiatachycardia variant of SND, programming of atrial ATP may be considered.164,165 IIb B In patients with syncope, cardiac pacing may be considered to reduce recurrent syncope when asymptomatic pause(s) >6 s due to sinus arrest is documented.133,134 IIb C Pacing may be considered in SND when symptoms are likely to be due to bradyarrhythmias, when the evidence is not conclusive. IIb C Pacing is not recommended in patients with bradyarrhythmias related to SND that are asymptomatic or due to transient causes that can be corrected and prevented.33 III C

ATP = antitachycardia pacing; DDD = dual-chamber, atrioventricular pacing; SND = sinus node dysfunction. aClass of recommendation. bLevel of evidence. ESC 2021 Downloaded from academic.oup.com/eurheartj/article/42/35/3427/6358547 by guest on 07 October 2026