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Kusumoto et al 2018 Bradycardia Clinical Practice Guidelines

Circulation. 2019;140:e382–e482. DOI: 10.1161/CIR.0000000000000628 August 20, 2019 e415 CLINICAL STATEMENTS AND GUIDELINES

resulting in a decrease in the rate of sinus node discharge. Beta blockers have a wide range of guideline-directed indications for patients after MI and for patients with chronic systolic heart failure.S5.4.4-5–S5.4.4-7 For patients who also have symptomatic sinus bradycardia some should be managed with permanent cardiac pacing so that essential pharmacologic therapy can be continued while, in others, stopping or decreasing the dose of the offending drug may be appropriate. In all cases, the relative benefits and risks of all therapies must be considered collectively for each individual patient.S5.4.4-5–S5.4.4-7 3.	 Tachy-brady syndrome describes a subset of symptomatic SND who have periods of fast heart rates (usually AF) and slow sinus rates or pauses. One of the most disabling symptoms of tachy-brady syndrome is recurrent syncope or presyncope secondary to transient asystolic pause that follows termination of paroxysmal episodes of atrial tachyarrhythmia (typically AF).S5.4.4-8 The severity of symptoms is often related to the length of pause. The pathophysiologic link between SND and AF, however, remains incompletely understood, and is an active area of investigation.S5.4.4-8 No randomized trial has specifically examined the use of permanent cardiac pacing in patients with tachybrady syndrome. Permanent pacing can alleviate the symptoms attributable to bradycardia or allow use of medications directed toward treatment of atrial tachyarrhythmias that might exacerbate bradycardia such as beta blockers.S5.4.4-9,S5.4.4-10 In those patients where bradycardia is associated with the atrial arrhythmia (AF with slow ventricular rates or post conversion pauses), treatment of atrial tachyarrhythmias with ablation may obviate the requirement for permanent pacing.S5.4.4-11,S5.4.4-12 4.	 Chronotropic incompetence describes an inappropriately blunted heart rate response to physiologic need associated with physical activity but is difficult to define by simple age dependent formulas. The diagnosis is typically suggested by ambulatory heart rate monitoring (provided that symptom diaries are accurately kept), or exercise electrocardiographic testing. Cardiac pacing with sensor-based rate-responsive feature has been used to increase the heart rate in times of sensed physical activity. There are different types of sensors that can track various physiologic parameters such as body motion and minute ventilation. One RCT, however, did not demonstrate any benefit in patients with SND.S5.4.4-13 At 6 months follow-up, there was no difference in total exercise time between the dualchamber paced group and the dual-chamber paced group with additional rate adaption algorithms programmed “on.” group. At one-year follow-up, there were no significant differences between 2 groups with respect to Specific Activity Scale or the secondary QOL endpoints. However, given that the overall right ventricular pacing percentage was >90% in this trial, any potential symptomatic benefit of rate-responsive feature could have been offset by the deleterious effect of high-percentage RV pacing with consequent dyssynchrony. Other nonrandomized studies have also shown variable clinical benefits from sensor-based rate responsive features.S5.4.4-14,S5.4.4-15 When used, careful programming of rate-responsive features is necessary. 5.	 Direct attribution of symptoms to SND should always be sought but can be difficult in some situations. A trial of oral theophylline may be considered to help correlate symptoms with bradycardia. In a randomized study of patients with symptomatic SND randomized to no treatment, oral theophylline, or permanent pacing, theophylline was associated with increased resting heart rate compared with control, although permanent pacing was superior for symptom control.S5.4.4-3 Similarly, in a nonrandomized case series of patients with SND, theophylline (200- 400 mg daily) decreased the frequency of sinus pauses and improved subjective symptoms in 16 of 17 patients.S5.4.4-4 In patients who are unwilling to undergo PPM implantation or who are not candidates for permanent pacing, oral theophylline could be considered for treatment of symptomatic SND.

5.4.4.1. Permanent Pacing Techniques and Methods for Chronic Therapy/Management of Bradycardia Attributable to SND

Recommendations for Permanent Pacing Techniques and Methods for Chronic Therapy/Management of Bradycardia Attributable to SND Referenced studies that support recommendations are summarized in Online Data Supplement 25.

COR LOE Recommendations

I B-R 1.  In symptomatic patients with SND, atrialbased pacing is recommended over single chamber ventricular pacing.S5.4.4.1-1–S5.4.4.1-4

I B-R 2.  In symptomatic patients with SND and intact atrioventricular conduction without evidence of conduction abnormalities, dual chamber or single chamber atrial pacing is recommended.S5.4.4.1-5

IIa B-R 3.  In symptomatic patients with SND who have dual chamber pacemakers and intact atrioventricular conduction, it is reasonable to program the dual chamber pacemaker to minimize ventricular pacing.S5.4.4.1-6

IIa C-EO 4.  In symptomatic patients with SND in which frequent ventricular pacing is not expected or the patient has significant comorbidities that are otherwise likely to determine the survival and clinical outcomes, single chamber ventricular pacing is reasonable.

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