Prolonged P-R interval in patients with chronic bifascicular block or LBBB did not increase severe perioperative bradyarrhythmias (P=1.00), and overall block progression was rare (1 of 103 cases).
Observational (n=103)
Does an additional first-degree A-V block increase the risk of perioperative block progression or severe bradyarrhythmias in patients with asymptomatic chronic bifascicular block or LBBB?
In patients with chronic bifascicular block or LBBB, perioperative progression to complete heart block is rare, and an additional first-degree A-V block does not increase the incidence of severe bradyarrhythmias, questioning the need for routine prophylactic temporary pacemakers.
Absolute Event Rate: 0% vs 1.8%
BACKGROUND: The incidence of perioperative bradyarrhythmias in patients with bifascicular or left bundle branch block (LBBB) and the influence of an additional first-degree atrioventricular (A-V) block has not been evaluated with 24-h Holter electrocardiographic monitoring. Therefore the authors assessed the rate of block progression and bradyarrhythmia in these patients. METHODS: Patients (n = 106) with asymptomatic bifascicular block or LBBB with or without an additional first-degree A-V block scheduled for surgery under general or regional anesthesia were enrolled prospectively. Three patients were excluded. Of the 103 remaining, 56 had a normal P-R interval and 47 had a prolonged one. Holter monitoring (CM2, CM5) was applied to each patient just before induction of anesthesia and was performed for 24 h. The primary endpoint of the study was the occurrence of block progression. As secondary endpoints, bradycardias 5 s were defined. RESULTS: Block progression to second-degree A-V block and consecutive cardiac arrest occurred in one case of LBBB without a prolonged P-R interval Severe bradyarrhythmias with hypotension developed in another eight patients: asystoles > 5 s occurred in two cases and six patients had bradycardias < 40/min. Pharmacotherapy was successful in these eight patients. There was no significant difference for severe bradyarrhythmias associated with hemodynamic compromise between patients with and without P-R prolongation (P = 1.00). CONCLUSIONS: In patients with chronic bifascicular block or LBBB, perioperative progression to complete heart block is rare. However, the rate of bradyarrhythmias with hemodynamic compromise proved to be relevant. Because an additional first-degree A-V block did not increase the incidence of severe bradyarrhythmias and pharmacotherapy by itself was successful in nearly all cases, routine prophylactic insertion of a temporary pacemaker in such patients should be questioned.
Gauss et al. (1998) conducted an observational in Asymptomatic chronic bifascicular block or left bundle branch block (n=103). Prolonged P-R interval vs. Normal P-R interval was evaluated on Occurrence of block progression. Prolonged P-R interval in patients with chronic bifascicular block or LBBB did not increase severe perioperative bradyarrhythmias (P=1.00), and overall block progression was rare (1 of 103 cases).
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