Prognosis and natural history of drug-related bradycardia

Atrioventricular block secondary to transient causes and long-term recurrence after an index event

BACKGROUND

Atrioventricular block (AVB) secondary to transient causes can recover with its correction. However, studies assessing predictors of recovery and long-term recurrence are lacking.

METHODS

Patients with advanced or complete AVB who had a reversible cause admitted in a single expert center were retrospectively studied. Patients with AVB secondary to acute coronary syndromes were excluded from analysis.

RESULTS

In a population of 162 patients, the main factors associated with recovery of rhythm without a permanent pacemaker (PPM) implantation were the presence of chronic kidney disease (CKD) on dialysis (OR 7.6; CI 95% 1.2-47.5 (p = .03)); greater serum potassium levels (OR 2.3; CI 95% 1.28-4.0 (p < .01)), higher dosage of bradycardic drugs (OR 2.2; CI 95% 1.13-4.4 (p = .02)), the association between different bradycardic drugs (OR 9.0; CI 95% 2.02-40.3 (p < .01)) and between drug therapy and hyperkaliemia (OR 5.2; CI 95% 1.8-15.1 (p < .01)). There was an overall high burden of conductions abnormalities which did not correlate with recovery of rhythm (OR 0.5; CI 95% 0.19-1.5 (p = .23)). In 29 patients (17.9%) there was a correction of the AVB. During a maximum follow-up of 130 months, 24 patients (82.8%) had a recurrence which warranted a PPM. In the overall cohort only five patients (3%) had sustained recovery of rhythm.

CONCLUSIONS

Recovery of AVB was mainly observed with higher doses of drug therapy, higher serum potassium levels or a combination of factors and regardless of baseline conduction abnormalities. The high rate of recurrence during follow-up warrants a close follow-up or PPM implantation at index admission.

Chronic Administration of Ion Channel Blockers Impact Microglia Morphology and Function in a Murine Model of Alzheimer's Disease

As the population ages, a high prevalence of multimorbidity will affect the way physicians need to think about drug interactions. With microglia's important involvement in the pathology and progression of Alzheimer's disease (AD), understanding whether systemically administered drugs intended for other affections could impact microglia function, already impacted by the presence of beta-amyloid, is important. The aim of this study was to evaluate morphological changes of microglia, using in vivo 2-photon laser scanning microscopy, in a murine model of AD under systemic administration of sodium or calcium ion channel blockers in order to establish potential effects that these drugs might have on microglia under neuro-inflammatory conditions. A total of 30 mice (age 14-16 weeks, weight 20-25 g) were used, with 25 APP randomly divided into three groups. The remaining animals were CX3CR1GFP/GFP male mice (n = 5) used as WT controls. After baseline behavior testing, all animals received daily intraperitoneal injections for 30 days according to the assigned group [WT (n = 5), Control (n = 5), Carbamazepine (n = 10), and Verapamil (n = 10)]. The results showed that the Verapamil treatment improved short-term memory and enhanced exploratory behavior in APP mice. The Carbamazepine treatment also improved short-term memory but did not elicit significant changes in anxiety-related behavior. Both Verapamil and Carbamazepine reduced the surveillance speed of microglia processes and changed microglia morphology in the cortex compared to the Control group. Due to their complex molecular machinery, microglia are potentially affected by drugs that do not target them specifically, and, as such, investigating these interactions could prove beneficial in our management of neurodegenerative pathologies.

Incidence and predictors of pacemaker implantation at follow-up after reversible high-degree sinus node dysfunction or atrioventricular block

BACKGROUND

A pacemaker implantation is not indicated in cases of reversible high-degree symptomatic sinus node dysfunction (SND) and atrioventricular block (AVB). However, it remains uncertain whether these reversible automaticity/conduction disorders may recur in some patients at follow-up, in the absence of reversible cause. This retrospective study aimed to determine the incidence and predictive factors of permanent pacemaker (PPM) implantation at follow-up and after reversible high-degree SND/AVB.

METHODS

Based on medical electronic files codes, we identified patients who were hospitalized in our cardiac intensive care unit between January 2003 and December 2020 due to reversible high-degree SND/AVB and who were discharged from the hospital alive and without PPM implantation. Acute myocardial infarction and post-cardiac surgery patients were excluded. We categorized the patients according to the need for PPM at follow-up due to non-reversible high-degree SND/AVB.

RESULTS

Of the 93 patients included, 26 patients (28%) were readmitted for PPM implantation at follow-up after hospital discharge. Among baseline characteristics, compared with patients who did not have high-degree SND/AVB recurrence, those who had subsequent PPM implantation had less frequent previous hypertension (70% vs. 46%, p = .031). Regarding the initial causes of reversible SND/AVB, isolated hyperkalemia was found more often in the patients readmitted for PPM (19% vs. 3% vs. p = .017). Moreover, recurrence of high-degree SND/AVB was significantly associated with the presence of intraventricular conduction disorders (either bundle branch block or left bundle branch hemiblock) on ECG at discharge (36% in patients without PPM vs. 68% in PPM patients, p = .012).

CONCLUSION

Almost one third of the patients discharged alive from the hospital after a reversible high-degree SND/AVB needed a pacemaker implantation at follow-up. Complete bundle branch block or left bundle branch hemiblock on discharge ECG after recovery of atrioventricular conduction and/or sinus automaticity was associated with a greater risk of recurrence leading to pacemaker implantation.

Myringosclerosis as a predictor of the requirement for a permanent pacemaker in patients with drug-related atrioventricular block

AIMS

Drug-related atrioventricular block (DR-AVB) may develop in patients with underlying latent degenerative conduction disorders, especially with antiarrhythmics and antihypertensives. Although, according to the current guidelines, reversal is achieved with cessation of the inducing agent, this is not the case for nearly half of the patients. The pathophysiological processes of DR-AVB and myringosclerosis include systemic inflammation and degeneration. This study investigated the role of myringosclerosis in predicting irreversible high-grade DR-AVB despite drug cessation.

METHODS

This observational, non-randomized, prospective study involved 152 patients with high-grade DR-AVB, 72 of whom had reversible DR-AVB and 80 had irreversible DR-AVB and required permanent pacemakers. The patients' demographic, clinical, echocardiographic, and laboratory characteristics were recorded. Otoscopic tympanic membrane examinations for myringosclerosis were performed.

RESULTS

There were no major differences in demographic, echocardiographic or laboratory characteristics between the two groups or previous medications. The median monitoring time with a temporary pacemaker was significantly longer in the irreversible than in the reversible group (5 [4-7] days vs. 2 [1-5] days; P<0.001). The incidence of myringosclerosis was significantly higher in the irreversible than in the reversible group (61.3% vs. 22.2%; P=0.001). Multivariate logistic regression analysis showed that myringosclerosis was an independent predictor of irreversible DR-AVB (odds ratio: 1.703, 95% confidence interval: 1.194-3.058; P=0.01).

CONCLUSION

Myringosclerosis is a readily available, inexpensive, and non-invasive assessment and is a marker of inflammation and degeneration that can predict irreversible DR-AVB.

Clinical characteristics of BRASH syndrome: Systematic scoping review

BACKGROUND

Bradycardia, renal failure, atrioventricular (AV) nodal blockade, shock, and hyperkalemia (BRASH) syndrome is a recently-established entity precipitated by medication-induced AV nodal blockade. Despite its serious consequences, including death, clinical presentations, risk factors, and outcomes of the syndrome have not been well defined. We aim to summarize the existing evidence of BRASH syndrome.

METHODS

According to the PRISMA Extension for Scoping Reviews, we performed a search on MEDLINE and EMBASE for articles with keywords including"BRASH syndrome" and "bradycardia, renal failure, atrioventricular nodal blockade, shock, and hyperkalemia," from the inception of these databases to March 4, 2022.

RESULTS

34 articles, including one observational study, 15 conference abstracts, and 18 case reports and case series, were included. While most patients were on beta blockers (83.3%) or calcium channel blockers (45.2%), other medications such as amiodarone were identified as precipitating agents. Atropine or glucagon were ineffective in reversing patients' symptoms, and 59.5% required inotropes or chronotropes. 7.1% expired due to BRASH syndrome.

CONCLUSIONS

This systematic review summarizes the clinical characteristics of BRASH syndrome. Further studies to identify risks associated with the onset of BRASH syndrome and awareness of the critical syndrome are warranted.

Bradycardia in Older Patients in a Single-Center Emergency Department: Incidence, Characteristics and Outcomes

Objective

This study aimed to explore data associated with the characteristics, incidence, and outcomes of older patients with symptomatic bradycardia presenting to the emergency department (ED).

Methods

We prospectively reviewed data of all patients aged 60 years and older who visited our ED with symptomatic bradycardia during 8AM-12PM between June 4, 2018, and June 10, 2019. The outcomes were the incidence of symptomatic bradycardia and adverse events (recurrent bradycardia, rate of ED revisits, subsequent hospitalization, mortality rate, and composite outcomes) at 30 days and 180 days.

Results

A total of 3297 patients visited the ED. Of these, 205 patients had symptomatic bradycardia. The incidence of symptomatic bradycardia was 6.2% (205/3297). One hundred fourteen patients (55.7%) were female, and the mean age was 74.9 (SD, 9) years. One-third of bradycardia patients (80 patients [39.0%]) were admitted to the hospital, 32 of whom because of unstable bradycardia. Ten of these 32 (30%) patients died during hospitalization from causes unrelated to bradycardia. One-third of unstable bradycardia patients had dyspnea (10/32 patients [31.3%]) followed by chest pain and altered mental status, respectively. ED revisit was the most common adverse event after 30 days (10.8%) and 180 days (20.3%). End-stage renal disease with hemodialysis was associated with adverse outcomes at 30 days (odds ratio, 2.34; 95% confidence interval, 1.30–20.87).

Conclusion

The incidence of symptomatic bradycardia among older adults was 6.2% in one urban ED. End-stage renal disease with hemodialysis was associated with adverse outcomes at 30 days. Larger studies should confirm this association and investigate methods of minimizing adverse outcomes.

Systemic immune-inflammation index as a tool for predicting the need for a permanent pacemaker in patients with drug-induced atrioventricular block

BACKGROUND

Drug-induced atrioventricular block (AVB) is generally considered reversible and does not require a permanent pacemaker implantation (PPM). However, some studies have demonstrated a failure of AVB cessation even when the inducing agent has been discontinued. This study has investigated the use of systemic immune-inflammation index (SII) to predict irreversible drug-induced AVB after drug discontinuation.

METHOD

Files of patients with high-degree AVB that required a temporary pacemaker (TPM) were retrospectively analyzed. Sixty-three patients in which AVB was drug-induced were included in the study. The patients were divided into the following two groups: (1) those whose AVB reversed after discontinuation of the related drug, and (2) those in which AVB did not reverse.

RESULTS

AVB reversed in 24 patients (38%) after the inducing agent was discontinued while in the remaining 39 patients (62%) PPM was required. The most common drugs to induce AVB were beta-blockers (n = 46, 73%). Follow-up time with TPM was significantly longer in the irreversible group (2.91 ± 1.05 days vs. 4.94 ± 2.15 days, p < .001). Multivariate logistic regression analysis showed that SII (odds ratio [OR] = 1.002; 95% confidence interval [CI] = 1.000-1.003; p = .01) was an independent predictor of the requirement for a PPM. An SII > 752.05 was found to be a predictor of irreversible AVB requiring PPM with a sensitivity of 64% and specificity of 75% (receiving-operating characteristics [ROC] area under the ROC curve [AUC]: 0.704, 95% CI = 0.570-0.838, p = .007).

CONCLUSION

Approximately 2/3 of drug-induced high-degree AVBs are irreversible. SII is an easily available and cheap inflammatory biomarker that can be used to predict irreversible AVB.

Atrioventricular block in patients undergoing treatment with bradycardic drugs. Predictors of pacemaker requirement

INTRODUCTION AND OBJECTIVES

Atrioventricular block (AVB) in the presence of bradycardic drugs (BD) can be reversible, and pacemaker implantation is controversial. Our objective was to analyze the pacemaker implantation rate in the mid-term, after BD suspension, and to identify predictive factors.

METHODS

We performed a cohort study that included patients attending the emergency department with high-grade AVB in the context of BD. We studied the persistence of AVB after BD discontinuation, recurrence in patients with AVB resolution, and the predictive variables associated with pacemaker requirement at 3 years.

RESULTS

Of 127 patients included (age, 79 [71-83] years), BAV resolved in 60 (47.2%); among these patients, recurrence occurred during the 24-month median follow-up in 40 (66.6%). Pacemaker implantation was required in 107 patients (84.3%), despite BD discontinuation. On multivariable analysis, the variables associated with pacemaker need at 3 years were heart rate <35 bpm (OR, 8.12; 95%CI, 1.82-36.17), symptoms other than syncope (OR, 4.09; 95%CI, 1.18-14.13), and wide QRS (OR, 5.65; 95%CI, 1.77-18.04). Concomitant antiarrhythmic treatment was associated with AVB resolution (OR, 0.12; 95%CI, 0.02-0.66).

CONCLUSIONS

More than 80% of patients with AVB secondary to BD require pacemaker implantation despite drug discontinuation. Predictive variables were wide QRS, heart rate <35 bpm, and clinical presentation other than syncope.

Rate or Rhythm Control in Older Atrial Fibrillation Patients: Risk of Fall-Related Injuries and Syncope

OBJECTIVES

Management of atrial fibrillation (AF) with rate and/or rhythm control could lead to fall-related injuries and syncope, especially in the older AF population. We aimed to determine the association of rate and/or rhythm control with fall-related injuries and syncope in a real-world older AF cohort.

DESIGN

A retrospective cohort study.

SETTING

Danish nationwide administrative registries from 2000 to 2015.

PARTICIPANTS

A total of 100 935 patients with AF aged 65 years or older claiming prescription of rate-lowering drugs (RLDs) and/or anti-arrhythmic drugs (AADs) were included. We compared the use of rate-lowering monotherapy with rate-lowering dual therapy, AAD monotherapy, and AAD combined with rate-lowering therapy.

MEASUREMENTS

Outcomes were fall-related injuries and syncope as a composite end point (primary) or separate end point (secondary).

RESULTS

In this population, the median age was 78 years (interquartile range [IQR] = 72-84 y), and 53 481 (53.0%) were women. During a median follow-up of 2.1 years (IQR = 1.0-5.1), 17 132 (17.0%) experienced a fall-related injury, 5745 (5.7%) had a syncope, and 21 093 (20.9%) experienced either. Compared with rate-lowering monotherapy, AADs were associated with a higher risk of fall-related injuries and syncope. The incidence rate ratio (IRR) for the composite end point was 1.29 (95% confidence interval [CI]: 1.17-1.43) for AAD monotherapy and 1.46 [95% CI = 1.34-1.58] for AAD combined with rate-lowering therapy. When stratifying by individual drugs, amiodarone significantly increased the risk of fall-related injuries and syncope (IRR = 1.40 [1.26-1.55]). Compared with more than 180 days of rate-lowering monotherapy, a higher risk of all outcomes was seen in the first 90 days of any treatment; however, the greatest risk was in the first 14 days for those treated with AADs.

CONCLUSION

In AF patients aged 65 years and older, AAD use was associated with a higher risk of fall-related injuries and syncope, and the risk was highest within the first 14 days for those treated with AADs. Only amiodarone use was associated with a higher risk. J Am Geriatr Soc 67:2023-2030, 2019.

Rate and rhythm therapy in patients with atrial fibrillation and the risk of pacing and bradyarrhythmia

BACKGROUND

Management of atrial fibrillation (AF) with rate and rhythm therapy can cause bradyarrhythmia.

OBJECTIVES

To assess overall risk, temporal risk, and subgroup at risk of bradyarrhythmia-related events by rate and/or rhythm therapy drugs.

METHODS

Using Danish nationwide registries, patients with AF between 2000 and 2014 were included if prescribed with rate-lowering drugs (RLDs) or antiarrhythmic drugs (AADs). An adjusted time-dependent Poisson regression model estimated the association between RLDs and AADs with a composite endpoint of pacemaker, temporary pacing, and bradyarrhythmia hospitalization. Secondary outcomes were each individual event.

RESULTS

Among 135,017 AF patients, 9196 (6.8%) patients experienced the composite endpoint with a median follow-up of 3.7 (interquartile range [IQR]: 1.6-7.0) years. Median age was 74 (IQR: 65-82) years and 47.6% were women. With rate-lowering monotherapy as the reference, the incidence rate ratios (IRR) (95% confidence interval) for the composite endpoint were 1.36 (1.29-1.43) for rate-lowering dual therapy, 1.62 (1.43-1.84) for antiarrhythmic monotherapy, and 2.49 (2.29-2.71) for AAD combined with RLDs. Similar trend was found for each secondary outcome. Particularly amiodarone increased the risk. This association was strongest within the first 2 weeks of treatment. In those treated with AAD combined with RLDs, high-risk populations were patients ≥70 years (IRR: 3.35 [2.51-4.45] compared to patients <60 years), and women (IRR: 1.35 [1.15-1.57], compared to men).

CONCLUSIONS

In real-world AF patients, rate-lowering dual therapy, antiarrhythmic monotherapy, and AADs combined with RLDs were positively associated with bradyarrhythmia-related events. The risk was highest in those treated with amiodarone, in the initial 2 weeks of treatment, in women, and in the elderly.

Admission Heart Rate Is a Determinant of Effectiveness of Beta-Blockers in Acute Myocardial Infarction Patients

BACKGROUND

Beta-blockers are standard therapy for acute myocardial infarction (AMI). However, despite current advances in the management of AMI, it remains unclear whether all AMI patients benefit from β-blockers. We investigated whether admission heart rate (HR) is a determinant of the effectiveness of β-blockers for AMI patients. Methods and Results: We enrolled 3,283 consecutive AMI patients who were admitted to 28 participating institutions in the Japanese Registry of Acute Myocardial Infarction Diagnosed by Universal Definition (J-MINUET) study. According to admission HR, we divided patients into 3 groups: bradycardia (HR <60 beats/min, n=444), normocardia (HR 60 to ≤100 beats/min, n=2,013), and tachycardia (HR >100 beats/min, n=342). The primary endpoint was major adverse cardiac events (MACE), including all-cause death, non-fatal MI, non-fatal stroke, heart failure (HF), and urgent revascularization for unstable angina, at 3-year follow-up. Beta-blocker at discharge was significantly associated with a lower risk of MACE in the tachycardia group (23.6% vs. 33.0%; P=0.033), but it did not affect rates of MACE in the normocardia group (17.8% vs. 18.4%; P=0.681). In the bradycardia group, β-blocker use at discharge was significantly associated with a higher risk of MACE (21.6% vs. 12.7%; P=0.026). Results were consistent for multivariable regression and stepwise multivariable regression.

CONCLUSIONS

Admission HR might determine the efficacy of β-blockers for current AMI patients.

Patients with atrial fibrillation and permanent pacemaker: Temporal changes in patient characteristics and pharmacotherapy

Background

The management of patients with non-valvular atrial fibrillation (NVAF) with rate-lowering or anti-arrhythmic drugs has markedly changed over the last decade, but it is unknown how these changes have affected patients with NVAF with a permanent pacemaker (PPM).

Methods

Through Danish nationwide registries, patients with NVAF and a PPM were identified from 2001 to 2012. Changes in concomitant pharmacotherapy and comorbidities were tested using the Cochran–Armitage trend test and linear regression. Patients with NVAF were identified to calculate the proportional amount of PPM implants.

Results

A total of 12,231 NVAF patients with a PPM were included in the study, 55.6% of which were men. Median age was 78 years (interquartile range 70–84). From 2001 to 2012, the number of NVAF patients with a PPM increased from 850 to 1344, while the number of NVAF patients increased from 67,478 to 127,261. Thus, the proportional amount of NVAF patients with a PPM decreased from 1.3% to 1.1% (p = 0.015). Overall 45.9% had atrial fibrillation (AF) duration less than one year and the proportion declined from 55.5% to 42.4% (p <0.001). Diabetes mellitus increased from 7.2% to 16.8% (p <0.001). Heart failure (HF) decreased from 36.7% to 29.3% (p = 0.010) and ischemic heart disease (IHD) decreased from 32.4% to 26.1% (p <0.001). Beta-blocker use increased from 38.1% to 58.0% (p <0.001), while digoxin and anti-arrhythmic drug use decreased over time.

Conclusion

From 2001 to 2012, the absolute number of NVAF patients with a PPM increased while the proportional amount decreased. The number of NVAF patients receiving a PPM within one year of AF diagnosis decreased. The prevalence of DM increased, while the prevalence of HF and IHD was high but decreasing. The use of beta-blockers increased markedly, while use of digoxin and anti-arrhythmic drugs decreased over time.

Beta-blocker use and risk of symptomatic bradyarrhythmias: a hospital-based case-control study

OBJECTIVE

To investigate the risk factors of symptomatic bradyarrhythmias in relation to β-blockers use.

METHODS

A hospital-based case-control study [228 patients: 108 with symptomatic bradyarrhythmias (cases) and 120 controls] was conducted in Sultanah Aminah Hospital, Malaysia between January 2011 and January 2014.

RESULTS

The mean age was 61.1 ± 13.3 years with a majority of men (68.9%). Cases were likely than control to be older, hypertensive, lower body mass index and concomitant use of rate-controlling drugs (such as digoxin, verapamil, diltiazem, ivabradine or amiodarone). Significantly higher level of serum potassium, urea, creatinine and lower level of estimated glomerular filtration rate (eGFR) were observed among cases as compared to controls. On univariate analysis among patients on β-blockers, older age (crude OR: 1.07; 95% CI: 1.03-1.11, P = 0.000), hypertension (crude OR: 5.6; 95% CI: 1.51-20.72, P = 0.010), lower sodium (crude OR: 0.04; 95% CI: 0.81-0.99, P = 0.036), higher potassium (crude OR: 2.36; 95% CI: 1.31-4.26, P = 0.004) and higher urea (crude OR: 1.23; 95% CI: 1.11-1.38, P = 0.000) were associated with increased risk of symptomatic bradyarrhythmias; eGFR was inversely and significantly associated with symptomatic bradyarrhythmias in both 'β-blockers' (crude OR: 0.97; 95% CI: 0.96-0.98, P = 0.000) and 'non-β-blockers' (crude OR: 0.99; 95% CI: 0.97-0.99, P = 0.023) arms. However, eGFR was not significantly associated with symptomatic bradyarrhythmias in the final model of both 'β-blockers' (adjusted OR: 0.98; 95% CI: 0.96-0.98, P = 0.103) and 'non-β-blockers' (adjusted OR: 0.99; 95% CI: 0.97-1.01, P = 0.328) arms. Importantly, older age was a significant predictor of symptomatic bradyarrhythmias in the 'β-blockers' as compared to the 'non-β-blockers' arms (adjusted OR: 1.09; 95% CI: 1.03-1.15, P = 0.003 vs. adjusted OR: 1.03; 95% CI: 0.98-1.09, P = 0.232, respectively).

CONCLUSION

Older age was a significant predictor of symptomatic bradyarrhythmias in patients on β-blockers than those without β-blockers.

Evaluation of azithromycin induced cardiotoxicity in rats

Although there are possible cardiovascular adverse effects associated with the azithromycin treatment according to some case reports and cohort studies, there is no experimental study evaluating cardiotoxicity in repeated pharmacological doses of this drug. In our study, 15 mg/kg and 30 mg/kg azithromycin were orally administered to rats for 14 days to evaluate the cardiotoxicity of this drug. ECGs of the azithromycin-treated and control animals were recorded. Blood samples were assayed to determine LDH and CK-MB levels. Additionally, CAT, SOD, GSH and MDA levels of heart tissues were measured. According to our ECG recordings, decreased heart rate, prolonged PR and QT intervals, QRS complex and T wave abnormalities were observed in 30 mg/kg azithromycin-administered group significantly when compared with control group. Plasma CK-MB and LDH levels were increased in 30 mg/kg azithromycin-administered group significantly when compared to the control group. In heart tissues, CAT, SOD and GSH levels were decreased while MDA levels were increased in both azithromycin-administered groups significantly when compared with the control group. In conclusion, our findings supported the possible cardiotoxicity risk with azithromycin treatment and also, oxidative stress, which was induced by azithromycin in our study, was thought to be occurred secondary to cardiac toxicity of the drug.

Severe iatrogenic bradycardia related to the combined use of beta-blocking agents and sodium channel blockers

Purpose

Drug-induced bradycardia is common during antiarrhythmic therapy; the major culprits are beta-blockers. However, whether other antiarrhythmic drugs are also a significant cause of this, alone or in combination with beta-blockers, is not well known.

Methods

We retrospectively investigated the records of all patients hospitalized at our institution for drug-related bradycardia from the years 2004 to 2012. Patients with cardiac disease and electrolytic or hormonal abnormalities that could cause bradyarrhythmias were excluded.

Results

Eight patients were identified (mean age, 79±5 years; range, 71–85 years; 6 women). Three patients were taking only beta-blockers (hereafter referred to as the BB group), while five patients were on both beta-blockers and Na channel blockers (hereafter referred to as the BB + Na group). Heart rates ranged from 20∼49 beats/minute on arrival. The initial electrocardiogram showed sinus bradycardia (n=6) or sinus arrest with escape beats (n=2). QRS duration was 80–100 ms. The clinical presentation of the BB + Na group was considerably worse than that of the BB group, and included cardiogenic shock and heart failure. Four of the BB + Na patients had been on their medications for over 300 days. The BB group recovered solely with drug discontinuation, while 4 of the 5 patients in the BB + Na group needed additional treatments, such as intravenous administration of atropine or adrenergic agonist and temporary pacing. Bradycardia did not recur during follow-up (median, 687 days).

Conclusion

Although wide QRS ventricular tachyarrhythmia is a better known proarrhythmic effect of Na channel blockers, life-threatening bradycardia may also occur in combination with beta-blockers in the elderly, even months after the start of medication, and at plasma concentrations that do not prolong QRS width.

Transient bradycardia induced by thiopentone sodium: a unique challenge in the management of refractory status epilepticus

Thiopentone sodium is one of the important drugs in the armamentarium for terminating refractory status epilepticus, a neurological emergency. We report a case of thiopentone-related bradycardia during the management of the new onset refractory status epilepticus in a young man, which was circumvented by prophylactic insertion of temporary pacemaker while thiopentone infusion was continued. A systematic approach was employed to manage the status epilepticus, including infusion of thiamine and glucose followed by antiepileptic drugs. The patient was ventilated and infused with lorazepam, phenytoin, sodium valproate, levetiracetam and midazolam followed by thiopentone sodium. With the introduction of thiopentone the seizures could be controlled but the patient developed severe bradycardia and junctional rhythm. The bradycardia disappeared when thiopentone was withdrawn and reappeared when the drug was reintroduced. Propofol infusion was tried with no respite in seizures. Later thiopentone sodium was reintroduced after inserting temporary cardiac pacemaker. Seizure was controlled and patient was weaned off the ventilator.

Management of patients with drug-induced atrioventricular block

OBJECTIVE

To identify the frequency of atrioventricular (AV) conduction improvement after discontinuation of the culprit drug in patients with AV block.

BACKGROUND

AV blockers are considered as reversible causes of AV block that do not require pacemaker (PM) implantation. However, controversial reports declared that a major part of these drug-induced AV blocks are persistent or recurrent.

METHODS

Of 668 consecutive patients with symptomatic type II second- or third-degree AV block, 2:1 AV block, atrial fibrillation, and bradyarrhythmia, 108 patients (62 patients enrolled prospectively) using AV blockers without myocardial infarction, electrolyte abnormalities, digitalis toxicity, and vasovagal syncope were enrolled into the present study. The level of AV block (AV-nodal or infranodal) was defined according to electrocardiographic characteristics.

RESULTS

The most frequent culprit medications were β-blockers followed by digoxin. Drug discontinuation was followed by resolution of AV block in 72% of cases, whereas spontaneous resolution of AV block occurred in only 6.6% of patients who had AV block in the absence of medications. However, 27% of patients with improved AV conduction experienced a recurrence of AV block despite discontinuation of the culprit drug. Twenty-one of 24 carvedilol-induced AV blocks resolved after discontinuation of the drug and never recurred, whereas 24 of 36 metoprolol-induced AV blocks persisted or recurred. A digoxin-induced AV block usually improved (28 of 39) after withdrawal of the drug. Roughly half of the patients with drug-induced AV block underwent permanent PM implantation.

CONCLUSION

Drug-induced AV block is a serious disease that requires a permanent PM for almost half of the patients.