Intravenous diltiazem for the treatment of patients with atrial fibrillation or flutter and moderate to severe congestive heart failure

Prehospital Treatment of Atrial Fibrillation: Infusion Pump for Bolus and Infusion?

OBJECTIVE

The prehospital treatment for stable patients with atrial fibrillation with rapid ventricular response is rate-controlling agents such as calcium channel blockers, often diltiazem given as a bolus. At our agency we encourage the use of a bolus given via the infusion pump over two to four minutes immediately followed by a maintenance infusion, given concerns of recurrent tachycardia or hypotension secondary to rapid bolus administration. We examined if administering a bolus and infusion via an infusion pump shows better heart rate (HR) control at arrival to the emergency department (ED) compared with administration of a bolus only, while maintaining hemodynamic stability during transport. We also analyzed if a patient received a second bolus within 60 min of arrival to the ED.

METHODS

We used a retrospective propensity-matched cohort of prehospital patients with atrial fibrillation for whom diltiazem was administered, from 1/1/2018 to 12/31/2021, in our system of 10 New Jersey paramedic units. We analyzed the age, gender, and initial HR and used it to match groups. We analyzed the mode and time of administration, dosage of the bolus, and presence of hypotension prehospitally.

RESULTS

The matched groups contained 145 patients who received a prehospital diltiazem bolus only (BO) and 146 patients who received a diltiazem bolus and infusion (BI). There was no significant difference between the mean change in HR from initial paramedic arrival to ED arrival between the two groups (BO 38 vs. BI 34, p = 0.16). There was no significant difference in the need for a second bolus within the first 60 min of arrival to the ED (BO 9.7% vs. BI 11.6%, p = 0.30). Patients in the BO group were more likely to experience prehospital hypotension then in the BI group (BO 17.2% vs BI 8.2%, p = 0.01), despite receiving smaller initial bolus doses (BO 14.2 mg vs. BI 17.4 mg, p < 0.001).

CONCLUSION

Our results show no significant differences in HR control or need for repeat bolus at the ED with the use of a diltiazem infusion following a diltiazem bolus. However, even when administering larger boluses, the use of an infusion pump resulted in less hypotension.

An Updated Review on the Role of Non-dihydropyridine Calcium Channel Blockers and Beta-blockers in Atrial Fibrillation and Acute Decompensated Heart Failure: Evidence and Gaps

PURPOSE

The 2021 European Society of Cardiology guidelines on acute and chronic heart failure (HF) recommend that non-dihydropyridine calcium channel blockers (NDCC) should be avoided in patients with HF with reduced ejection fraction. It also emphasizes that beta-blockers only be initiated in clinically stable, euvolemic patients. Despite these recommendations, NDCC and beta-blockers are often still employed in patients with AF with rapid ventricular response and acute decompensated HF. The relative safety and efficacy of these therapies in this setting is unclear.

METHODS

To address the question of the safety and efficacy of NDCC and beta-blockers for acute rate control in decompensated HF, we provide a perspective on the literature of NDCC and beta-blockers in chronic HF with reduced and preserved ejection fraction and AF, including trials on the management of AF with rapid ventricular response with and without HF.

RESULTS

Robust data demonstrates mortality benefits when beta-blockers are used in patients with chronic HF with reduced ejection fraction. The data that inform the contraindication of NDCC in HF with reduced ejection fraction are outdated and were not primarily designed to address the efficacy and safety of rate control of AF in patients with HF. Several studies indicate that for acute rate control, NDCC and beta-blockers are both efficacious therapies, especially in the setting of tachycardia-induced cardiomyopathy.

CONCLUSION

Future studies are needed to assess the safety and efficacy of beta-blockers and NDCC in both acute and chronic AF with HF with reduced and preserved ejection fraction.

Safety and Efficacy of Nondihydropyridine Calcium Channel Blockers for Acute Rate Control in Atrial Fibrillation with Rapid Ventricular Response and Comorbid Heart Failure with Reduced Ejection Fraction

The use of nondihydropyridine calcium channel blockers (NDCCBs) to achieve rate control in atrial fibrillation with the rapid ventricular rate (AF RVR) is not recommended in patients with comorbid heart failure with reduced ejection fraction (HFrEF) due to the concern for further blunting of contractility. However, these recommendations are extrapolated from data examining chronic NDCCB use in HFrEF patients, and comorbid AF was not analyzed. These recommendations also do not cite the hemodynamic effects or clinical outcomes of NDCCBs for acute rate control in HFrEF patients with AF RVR. It is our goal to open the discussion concerning the hemodynamic effects and safety profile of NDCCBs for acute rate control in this specific patient population. In the acute setting of AF RVR and HFrEF, there is a paucity of low-quality data on the safety and hemodynamic effects of NDCCBs, with mixed results. There has not been a clear signal toward adverse outcomes with NDCCBs, particularly for diltiazem. Data in this scenario is similarly limited for beta blockers, which provide the additional hemodynamic effect of the neurohormonal blockade, which provides a long-term mortality benefit to HFrEF patients. We support the cautious use of beta blockers as first-line therapy in clinical settings where an acute rate control strategy for AF RVR is warranted. We also support diltiazem as a reasonable second-line option, though the relative paucity of data calls for further research to validate this conclusion. Verapamil in this setting should be avoided until more data are available.

Management of atrial flutter and atrial fibrillation with rapid ventricular response in patients with acute decompensated heart failure: A systematic review

OBJECTIVE

The objective was to evaluate the comparative effectiveness and safety of pharmacological and nonpharmacological management options for atrial fibrillation/atrial flutter with rapid ventricular response (AFRVR) in patients with acute decompensated heart failure (ADHF) in the acute care setting.

METHODS

This study was a systematic review of observational studies or randomized clinical trials (RCT) of adult patients with AFRVR and concomitant ADHF in the emergency department (ED), intensive care unit, or step-down unit. The primary effectiveness outcome was successful rate or rhythm control. Safety outcomes were adverse events, such as symptomatic hypotension and venous thromboembolism.

RESULTS

A total of 6577 unique articles were identified. Five studies met inclusion criteria: one RCT in the inpatient setting and four retrospective studies, two in the ED and the other three in the inpatient setting. In the RCT of diltiazem versus placebo, 22 patients (100%) in the treatment group had a therapeutic response compared to 0/15 (0%) in the placebo group, with no significant safety differences between the two groups. For three of the observational studies, data were limited. One observation study showed no difference between metoprolol and diltiazem for successful rate control, but worsening heart failure symptoms occurred more frequently in those receiving diltiazem compared to metoprolol (19 patients [33%] vs. 10 patients [15%], p = 0.019). A single study included electrical cardioversion (one patient exposed with failure to convert to sinus rhythm) as nonpharmacological management. The overall risk of bias for included studies ranged from serious to critical. Missing data and heterogeneity of definitions for effectiveness and safety outcomes precluded the combination of results for quantitative meta-analysis.

CONCLUSIONS

High-level evidence to inform clinical decision making regarding effective and safe management of AFRVR in patients with ADHF in the acute care setting is lacking.

Use of Diltiazem in Chronic Rate Control for Atrial Fibrillation: A Prospective Case-Control Study

Atrial fibrillation (AF) is a multifaceted disease requiring personalised treatment. The aim of our study was to explore the prognostic impact of a patient-specific therapy (PT) for rate control, including the use of non-dihydropyridine calcium channel blockers (NDDC) in patients with heart failure (HF) or in combination with beta-blockers (BB), compared to standard rate control therapy (ST), as defined by previous ESC guidelines. This is a single-centre prospective observational registry on AF patients who were followed by our University Hospital. We included 1112 patients on an exclusive rate control treatment. The PT group consisted of 125 (11.2%) patients, 93/125 (74.4%) of whom were prescribed BB + NDCC (±digoxin), while 85/125 (68.0%) were HF patients who were prescribed NDCC, which was diltiazem in all cases. The patients treated with a PT showed no difference in one-year overall survival compared to those with an ST. Notably, the patients with HF in ST had a worse prognosis (p < 0.001). To better define this finding, we performed three sensitivity analyses by matching each patient in the PT subgroups with three subjects from the ST cohort, showing an improved one-year survival of the HF patients treated with PT (p = 0.039). Our results suggest a potential outcome benefit of NDCC for rate control in AF patients, either alone or in combination with BB and in selected patients with HF.

The Safety and Efficacy of Verapamil Versus Diltiazem Continuous Infusion for Acute Rate Control of Atrial Fibrillation at an Academic Medical Center

Purpose

Due to critical shortages of intravenous diltiazem in 2018, the Ohio State University Wexner Medical Center (OSUWMC) adopted intravenous verapamil as an alternative. However, there is a paucity of data supporting the use of intravenous verapamil infusions for rate control in the acute treatment of atrial arrhythmias. The purpose of this study was to determine the safety and efficacy of intravenous verapamil as compared with diltiazem for the acute treatment of atrial arrhythmias.

Methods

This retrospective, case-control study compared patients who received verapamil infusions between June 1 and September 30, 2018, with patients who received diltiazem infusions between June 1 and September 30, 2017, at OSUWMC. Patients were matched 1:1 based on age, sex, and the presence of comorbid heart failure with reduced ejection fraction (≤40%).

Results

A total of 73 patients who received at least 1 verapamil infusion and 73 patients who received at least 1 diltiazem infusion met inclusion criteria. The composite need for inotrope or vasopressor was similar for both groups (5% with verapamil versus 4% with diltiazem, P = .999). The rate of hypotension was similar between groups (37% versus 33% experiencing a systolic blood pressure <90 mm Hg, P = .603, and 27% versus 23% experiencing a mean arterial pressure <65 mm Hg, P = .704), as was the rate of bradycardia (19% versus 18%, P = .831). The efficacy outcomes of this study were similar for both groups, with 89% of patients in the verapamil group and 90% of patients in the diltiazem group achieving a heart rate less than 110 beats per minute (P = .785).

Conclusion

Intravenous verapamil and diltiazem infusions had similar safety and efficacy outcomes when used for acute treatment of atrial arrhythmias in the institutional setting.

The 2020 Canadian Cardiovascular Society/Canadian Heart Rhythm Society Comprehensive Guidelines for the Management of Atrial Fibrillation

The Canadian Cardiovascular Society (CCS) atrial fibrillation (AF) guidelines program was developed to aid clinicians in the management of these complex patients, as well as to provide direction to policy makers and health care systems regarding related issues. The most recent comprehensive CCS AF guidelines update was published in 2010. Since then, periodic updates were published dealing with rapidly changing areas. However, since 2010 a large number of developments had accumulated in a wide range of areas, motivating the committee to complete a thorough guideline review. The 2020 iteration of the CCS AF guidelines represents a comprehensive renewal that integrates, updates, and replaces the past decade of guidelines, recommendations, and practical tips. It is intended to be used by practicing clinicians across all disciplines who care for patients with AF. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system was used to evaluate recommendation strength and the quality of evidence. Areas of focus include: AF classification and definitions, epidemiology, pathophysiology, clinical evaluation, screening and opportunistic AF detection, detection and management of modifiable risk factors, integrated approach to AF management, stroke prevention, arrhythmia management, sex differences, and AF in special populations. Extensive use is made of tables and figures to synthesize important material and present key concepts. This document should be an important aid for knowledge translation and a tool to help improve clinical management of this important and challenging arrhythmia.

Sepsis With Preexisting Heart Failure: Management of Confounding Clinical Features

Preexisting heart failure (HF) in patients with sepsis is associated with worse clinical outcomes. Core sepsis management includes aggressive volume resuscitation followed by vasopressors (and potentially inotropes) if fluid is inadequate to restore perfusion; however, large fluid boluses and vasoactive agents are concerning amid the cardiac dysfunction of HF. This review summarizes evidence regarding the influence of HF on sepsis clinical outcomes, pathophysiologic concerns, resuscitation targets, hemodynamic interventions, and adjunct management (ie, antiarrhythmics, positive pressure ventilatory support, and renal replacement therapy) in patients with sepsis and preexisting HF. Patients with sepsis and preexisting HF receive less fluid during resuscitation; however, evidence suggests traditional fluid resuscitation targets do not increase the risk of adverse events in HF patients with sepsis and likely improve outcomes. Norepinephrine remains the most well-supported vasopressor for patients with sepsis with preexisting HF, while dopamine may induce more cardiac adverse events. Dobutamine should be used cautiously given its generally detrimental effects but may have an application when combined with norepinephrine in patients with low cardiac output. Management of chronic HF medications warrants careful consideration for continuation or discontinuation upon development of sepsis, and β-blockers may be appropriate to continue in the absence of acute hemodynamic decompensation. Optimal management of atrial fibrillation may include β-blockers after acute hemodynamic stabilization as they have also shown independent benefits in sepsis. Positive pressure ventilatory support and renal replacement must be carefully monitored for effects on cardiac function when HF is present.

Pharmacological management of atrial fibrillation in patients with heart failure with reduced ejection fraction: review of current knowledge and future directions

Introduction: Both heart failure with reduced ejection fraction (HFrEF) and atrial fibrillation (AF) independently cause significant morbidity and mortality. The two conditions commonly coexist and AF in the setting of HFrEF is associated with worse mortality, hospitalizations, and quality of life compared to HFrEF without AF. Despite the large burden of these conditions, there is no clear optimal management strategy for when they occur together.Areas covered: This review focuses on the pharmacological management of AF in HFrEF. Studies were identified through PubMed search of relevant keywords. The authors review key clinical trials that have influenced management strategies and guidelines. The authors focus on the classes of drugs used to treat AF for both rate and rhythm control strategies including beta-blockers, digoxin, amiodarone, and dofetilide. Additionally, the authors discuss select non-antiarrhythmic medications that affect AF in HFrEF. The authors highlight the strengths and weakness of the data supporting the use of these medications and suggest future directions.Expert opinion: The pharmacological treatment of AF in HFrEF will need further refinement alongside the emerging role of catheter ablation. Novel HF medications and antiarrhythmics offer new tools to prevent the development of AF, as well as for rate and rhythm control strategies.

Frequency of "on-label" use of intravenous diltiazem for rate control in patients with acute-onset atrial fibrillation or atrial flutter

Purpose

The study was designed to characterize "on-label" use of i.v. diltiazem in patients with acute atrial fibrillation or flutter (AFF).

Methods

An IRB-approved, single-center, retrospective, observational design was used. Eligible patients had acute AFF with heart rate >120 bpm and received i.v. diltiazem from June 1, 2012, to June 30, 2014. The primary outcome was frequency of on-label use of i.v. diltiazem, defined as use of at least one FDA-approved weight-based bolus dose followed by an infusion, if appropriate, in the absence of contraindications.

Results

A total of 300 patients were screened; 97 patients were included for analysis. I.V. diltiazem was used on-label in only 14 patients (14%). Of the 96 patients who received an initial diltiazem bolus injection, the median dose was significantly higher in patients for whom the diltiazem dose was on-label, as follows: 17.5 mg (interquartile range [IQR]), 10-20 mg vs. 10.0 mg (IQR, 10-20 mg), p < 0.02). Twenty-nine patients (35%) in the off-label group had a therapeutic response to diltiazem alone compared with 8 patients (57%) in the on-label group (p = 0.11). More patients treated with off-label diltiazem bolus injection required additional rate control medications (41% vs. 7%, p < 0.04).

Conclusion

In most patients, i.v. diltiazem was not used in accordance with FDA labeling. For most, i.v. diltiazem doses were lower than recommended and many of these patients required additional rate control medications to achieve a therapeutic response.

Treatment of Acute Atrial Fibrillation: Ventricular Rate Control and Restoration of Sinus Rhythm

Atrial fibrillation (AF) is a familiar arrhythmia seen in the emergency department and the general population. In the past it was treated in the majority of cases by controlling the ventricular rate, whether the AF is acute or chronic. However, ventricular rate control alone does not address the underlying problem and the patients still remain in AF, cardiac output and symptoms have not been optimally corrected. There is definite risk of thromboembolism. Restoration of sinus rhythm is the only way of resuming the normal conduction physiology of the heart and correcting these problems This article provides a review of the two major principles of rhythm treatment of acute AF: rate control and restoration of sinus rhythm. Transthoracic electrical cardioversion is the mainstay of treatment in haemodynamically unstable AF, whereas in stable AF, there is a choice between rate control and restoration of sinus rhythm, or they can be carried out in conjunction with each other.

Comparison of Weight-Based Dose vs. Standard Dose Diltiazem in Patients with Atrial Fibrillation Presenting to the Emergency Department

BACKGROUND

Despite evidence-based recommended weight-based (WB) dosing of diltiazem for the initial treatment of atrial fibrillation (AF) with rapid ventricular response (RVR), many providers utilize lower initial doses of diltiazem.

OBJECTIVE

We sought to determine whether a low, standard dose of diltiazem is noninferior to WB diltiazem as an initial bolus dose in the treatment of AF with RVR.

METHODS

This retrospective review included patients who presented to the emergency department (ED) of an urban, academic tertiary medical center experiencing AF with RVR from November 2010 to August 2014. Adult patients were categorized by the dose of diltiazem received; 10 mg standard dose or 0.2-0.3 mg/kg WB dose. The primary outcome of successful treatment was defined as a composite of the following parameters 15 min after the initial bolus dose: heart rate (HR) < 100 beats/min, reduction of HR ≥ 20%, or a conversion to normal sinus rhythm.

RESULTS

Four hundred and fifty-six patients who received diltiazem were included for study evaluation (standard dose: n = 255 patients, WB: n = 201 patients). Baseline characteristics, medical history, and medication use before ED presentation were similar between the groups. Significant differences at baseline between the groups included weight and HR at presentation. The primary outcome of successful treatment was attained in 60.8% of the standard dose patients and 68.7% of the WB patients (p = 0.082).

CONCLUSIONS

In patients presenting to the ED, we found that standard dose diltiazem was noninferior to WB dosing in the initial treatment of AF with RVR.

Management strategies in atrial fibrillation in patients with heart failure

Atrial fibrillation (AF) and heart failure (HF) frequently occur together, and their coexistence is associated with a poor prognosis. AF and HF share risk factors, but their relationship involves complex hemodynamic, neurohormonal, inflammatory, ultrastructural, and electrophysiologic processes that extend beyond epidemiological associations. The shared mechanisms underlying AF and HF have important implications for the treatment of AF in patients with HF. This article focuses on reviewing contemporary data as it pertains to AF management in patients with HF and provides insight into investigational therapies currently under development.

Rhythm disturbances

Patients with cardiac rhythm disturbances may present in a variety of conditions. Patients may be unstable, requiring immediate interventions, or stable, allowing for a more deliberate approach. Rapid assessment of patient stability, underlying rhythm, and determination of appropriate interventions guides timely therapy. This article discusses the differential diagnosis and treatment of adult patients presenting with primary bradyarrhythmias and tachyarrhythmias, with the exception of atrial fibrillation and atrial flutter, covered elsewhere in this issue. A concise approach to diagnosis and determination of appropriate therapy is presented.

Special cases in acute heart failure syndromes: atrial fibrillation and wide complex tachycardia

Hospitalization for acute heart failure syndromes (AHFS) results in substantial in-hospital and postdischarge morbidity and mortality. Management of AHFS presents significant challenges, given the heterogeneity of the patient population and the differing etiologies underlying why patients present with acute decompensation. Arrhythmias in the setting of AHFS, such as atrial fibrillation and wide complex tachycardia, present additional challenges. Compounding this challenge is the paucity of evidence on which to base early management. General principles for the management of atrial fibrillation and wide complex tachycardia in the setting of emergency department AHFS are discussed.

Comparison of the effectiveness of intravenous diltiazem and metoprolol in the management of rapid ventricular rate in atrial fibrillation

OBJECTIVE

To compare the effectiveness of intravenous (IV) diltiazem and metoprolol in the management of rapid ventricular rate in atrial fibrillation (AF).

METHODS

This prospective, randomised study was conducted in the Emergency Department of the Uludag University Medical Faculty Hospital, Bursa, Turkey. Forty AF patients with a ventricular rate > or = 120/minute and systolic blood pressure > or = 95 mm Hg were included and randomised to receive IV diltiazem 0.25 mg/kg (maximum 25 mg) or metoprolol 0.15 mg/kg (maximum 10 mg) over 2 minutes. Blood pressures and heart rate were measured at 2, 5, 10, 15, and 20 minutes. Successful treatment was defined as fall in ventricular rate to below 100/minute or decrease in ventricular rate by 20% or return to sinus rhythm.

RESULTS

Between January 2000 and July 2002, 40 patients (18 men, 22 women) met the inclusion criteria. Of these 20 (8 men, 12 women; mean age 60.2 years, range 31-82) received diltiazem and 20 (10 men, 10 women; mean age 64.0 years, range 31-82) received metoprolol. The success rate at 20 minutes for diltiazem and metoprolol was 90% (n = 18) and 80% (n = 16), respectively. The success rate at 2 minutes was higher in the diltiazem group. The percentage decrease in ventricular rate was higher in the diltiazem group at each time interval. None of the patients had hypotension.

CONCLUSION

Both diltiazem and metoprolol were safe and effective for the management of rapid ventricular rate in AF. However, the rate control effect began earlier and the percentage decrease in ventricular rate was higher with diltiazem than with metoprolol.

Comparison of the effectiveness of intravenous diltiazem and metoprolol in the management of rapid ventricular rate in atrial fibrillation

OBJECTIVE

To compare the effectiveness of intravenous (IV) diltiazem and metoprolol in the management of rapid ventricular rate in atrial fibrillation (AF).

METHODS

This prospective, randomised study was conducted in the Emergency Department of the Uludag University Medical Faculty Hospital, Bursa, Turkey. Forty AF patients with a ventricular rate > or = 120/minute and systolic blood pressure > or = 95 mm Hg were included and randomised to receive IV diltiazem 0.25 mg/kg (maximum 25 mg) or metoprolol 0.15 mg/kg (maximum 10 mg) over 2 minutes. Blood pressures and heart rate were measured at 2, 5, 10, 15, and 20 minutes. Successful treatment was defined as fall in ventricular rate to below 100/minute or decrease in ventricular rate by 20% or return to sinus rhythm.

RESULTS

Between January 2000 and July 2002, 40 patients (18 men, 22 women) met the inclusion criteria. Of these 20 (8 men, 12 women; mean age 60.2 years, range 31-82) received diltiazem and 20 (10 men, 10 women; mean age 64.0 years, range 31-82) received metoprolol. The success rate at 20 minutes for diltiazem and metoprolol was 90% (n = 18) and 80% (n = 16), respectively. The success rate at 2 minutes was higher in the diltiazem group. The percentage decrease in ventricular rate was higher in the diltiazem group at each time interval. None of the patients had hypotension.

CONCLUSION

Both diltiazem and metoprolol were safe and effective for the management of rapid ventricular rate in AF. However, the rate control effect began earlier and the percentage decrease in ventricular rate was higher with diltiazem than with metoprolol.

Management of atrial fibrillation

Atrial fibrillation (AF) is the most common clinically important arrhythmia in veterinary medicine. Electrical cardioversion of AF to sinus rhythm is feasible, but pharmacologic rate control is an effective and achievable treatment strategy for most veterinary patients. Recent human trials suggest that rate control and rhythm control are almost equally beneficial. Nevertheless, AF can be a challenging arrhythmia to manage, because most affected animal shave numerous other concurring problems associated with the underlying heart disease that dictate or influence the clinician's choice of treatment and monitoring strategy for each patient.

Calcium chloride before i.v. diltiazem in the management of atrial fibrillation

Diltiazem is commonly used to treat atrial fibrillation or flutter (AFF) with rapid ventricular response (RVR). Although it is very effective for rate control, up to an 18% prevalence of reported diltiazem-induced hypotension [defined by systolic blood pressure (SBP) < 90 mm Hg], and a mean of 9.7% hypotension have been reported from several studies totaling over 450 patients. This hypotension may complicate therapy. Our objective was to determine if calcium chloride (CaCl(2)) pre-treatment would blunt a SBP drop after i.v. diltiazem, while allowing diltiazem to maintain its efficacy. A prospective, randomized, double-blind, placebo-controlled study was conducted. Seventy-eight patients with AFF and a ventricular rate of >/= 120 beats per minute were enrolled. Half received i.v. CaCl(2) pre-treatment; the other half received placebo. All patients then received i.v. diltiazem in a standard, weight-based dose. A second dose of CaCl(2) pre-treatment or placebo and diltiazem was given if clinically indicated for additional rate control. Both CaCl(2) and placebo pre-treatment groups had equal lowering of heart rate (p < 0.001). There were no adverse events in the calcium pre-treatment study arm. One patient in the placebo group became paradoxically more tachycardic and apneic after the diltiazem infusion. Although i.v. CaCl(2) seems to be equally safe compared to placebo as a pre-treatment in the management of AFF with RVR, we were unable to find a statistically significant blunting of SBP drop with CaCl(2) i.v. pre-treatment. Until further research determines a benefit exists, we cannot recommend i.v. CaCl(2) pre-treatment before diltiazem in the treatment of AFF with RVR.

Pharmacological rate control of atrial fibrillation

To control ventricular rate in patients with AF, physicians should seek to control heart rate at rest and with exertion. The goal has to be achieved while minimizing costs and adverse effects. For emergency use, i.v. diltiazem or esmolol are drugs useful because of their rapid onset of action. They have to be used with caution in patients with concomitant left ventricular failure symptoms, however. For most patients with AF, chronic control of the ventricular rate can be achieved with one drug. For the chronic control of ventricular rate in patients with AF and normal ventricular function, diltiazem, atenolol, are metoprolol are probably the drugs of choice. For patients with AF and structurally abnormal hearts, atenolol, metoprolol, or carvedilol are appropriate choices. Adequate ventricular rate control by pharmacological agents should be evaluated by either 24-hour Holter monitoring or a submaximal stress test to determine the resting and exercise ventricular rate. If the mean ventricular rate is not close to 80 beats per minute, or the heart rate on moderate exertion is not between 90 to 115 beats per minute, a second agent to control the rate should be added. Excessive reductions in ventricular rates that could limit exercise tolerance should be avoided.

Rate control in atrial fibrillation: choice of treatment and assessment of efficacy

The clinical relevance and high social costs of atrial fibrillation have boosted interest in rate control as a cost-effective alternative to long-term maintenance of sinus rhythm (i.e. rhythm control). Prospective studies show that rate control (coupled with thromboembolic prophylaxis) is a valuable treatment option for all forms of atrial fibrillation. The rationale for rate control is that high ventricular rates, frequently found in atrial fibrillation, lead to haemodynamic impairment, consisting of a variable combination of loss of atrial kick, irregularity in ventricular response and inappropriately rapid ventricular rate, depending on the type of underlying heart disease. Long-term persistence of tachycardia at a high ventricular rate can lead to various degrees of ventricular dysfunction and even to tachycardiomyopathy-related heart failure. Identification of this reversible and often concealed form of left ventricular dysfunction can permit effective management by rate (or rhythm) control. Although acute rate control (to reduce ventricular rate within hours) is still often based on digoxin administration, for patients without left ventricular dysfunction, calcium channel antagonists or beta-adrenoceptor antagonists (beta-blockers) are generally more appropriate and effective. In chronic atrial fibrillation, long-term rate control (to reduce morbidity/mortality and improve quality of life) must be adapted to patients' individual characteristics to grant control during daily activities, including exercise. According to current guidelines, the clinical target of rate control should be a ventricular rate below 80-90 bpm at rest. However, in many patients, assessment of the appropriateness of different drugs should include exercise testing and 24h-Holter monitoring, for which specific guidelines are needed. In practice, rate control is considered a valid alternative to rhythm control. Recent prospective trials (e.g. the Pharmacological Intervention in Atrial Fibrillation [PIAF] and the Atrial Fibrillation Follow-up Investigation of Rhythm Management [AFFIRM] trials) have shown that in selected patients, rate control provides similar benefits, more economically, in terms of quality of life and long-term mortality. The choice of a rate control medication (digoxin, beta-blockers, calcium channel antagonists or possibly amiodarone) or a non-pharmacological approach (mainly atrioventricular node ablation coupled with pacing) must currently be based on clinical assessment, which includes assessing the presence of underlying heart disease and haemodynamic impairment. Definite guidelines are required for each different subset of patients. Rate control is particularly tricky in patients with heart failure, for whom non-pharmacological options can also be considered. The preferred pharmacological options are beta-blockers for stabilised heart failure and digoxin for unstabilised forms.

Left ventricular performance during acute rate control in atrial fibrillation: the importance of heart rate and agent used

BACKGROUND

The relation between heart rate and left ventricular function during rate control in atrial fibrillation is incompletely understood.

METHODS

Twenty-four patients (age 67 +/- 11 years) with symptomatic recent onset rapid atrial fibrillation and rapid ventricular rate (> 110 bpm) were randomly assigned to receive either intravenous digoxin (13 mcg/kg) or intravenous diltiazem (0.25 mg/kg bolus plus a maintenance infusion). A portable radionuclide detector was used to collect validated measures of relative left ventricular volumes, along with heart rate data, every 15 seconds for 6 hours.

RESULTS

Heart rate decreased significantly at 15 minutes and 180 minutes in the diltiazem group (from 133 +/- 18 bpm to 111 +/- 26 bpm [P <.01] to 94 +/- 24 bpm [P <.001]) but not in the digoxin group (from 129 +/- 18 bpm to 126 +/- 17 bpm [P = NS] to 118 +/- 15 bpm [P = NS]). Left ventricular ejection fraction improved in both groups to a similar extent (from 39 +/- 10% to 50 +/- 8%, [P <.05] after diltiazem, and from 38 +/- 8% to 52 +/- 11% [P <.05] after digoxin at baseline vs 180 minutes, respectively). The ejection fraction vs heart rate slope was steeper in the digoxin group than in the diltiazem group (-0.34 +/- 0.18 vs -0.16 +/- 0.17, P =.048) indicating a more pronounced improvement in ejection fraction per unit decrease in heart rate.

CONCLUSION

In patients with acute atrial fibrillation, digoxin led to similar improvements in ejection fraction compared to diltiazem despite a slower and less potent heart rate slowing.

Successful use of iv diltiazem to control perioperative refractory complex atrial tachyarrhythmias in a patient with pneumoconiosis

PURPOSE

To present a patient with pneumoconiosis who developed a complex, life-threatening atrial tachyarrhythmia during anesthesia. Intravenous diltiazem was effective in controlling the ventricular rate and hemodynamics after failure of other antiarrhythmic drugs and direct current cardioversion.

CLINICAL FEATURES

A 79-yr-old man with pneumoconiosis complicated by cor pulmonale suffered from gout-related cellulitis of the left lower limb. Debridement of the left gangrenous big toe was carried out under general anesthesia. During anesthesia, a wide-QRS tachycardia occurred suddenly and a complex atrial tachyarrhythmia was later diagnosed. Hemodynamics deteriorated despite aggressive treatment with lidocaine, verapamil, direct current cardioversion, magnesium, digoxin and amiodarone. Correction of the underlying respiratory acidosis was not sufficient to control the rapid ventricular response. Eventually, iv diltiazem adequately controlled the rapid ventricular rate and quickly improved the deteriorating hemodynamics.

CONCLUSION

Life-threatening complex atrial tachyarrhythmias may occur in patients with chronic lung diseases perioperatively. Intravenous diltiazem was effective in the management of complex atrial tachyarrhythmia in a patient with underlying cor pulmonale.

Atrial fibrillation: beyond irregularly irregular: the basis for acute and chronic treatment

Today atrial fibrillation is the most prevalent sustained arrhythmia encountered in clinical practice; it places a heavy burden on the healthcare system. The purpose of this article is to explore the principles underlying the treatment of both acute and chronic atrial fibrillation.

Prevention of and medical therapy for atrial arrhythmias in heart failure

A large proportion of heart failure patients suffer from atrial arrhythmias, prime amongst them being atrial fibrillation (AF). Ventricular dysfunction and the syndrome of heart failure can also be a concomitant pathology in up to 50% of patients with AF. However this association is more than just due to shared risk factors, research from animal and human studies suggest a causal relationship between AF and heart failure. There are numerous reports of tachycardia-induced heart failure where uncontrolled ventricular rate in AF results in heart failure, which is reversible with cardioversion to sinus rhythm or ventricular rate control. However the relationship extends beyond tachycardia-induced cardiomyopathy. Optimal treatment of AF may delay progressive ventricular dysfunction and the onset of heart failure whilst improved management of heart failure can prevent AF or improve ventricular rate control. Prevention and treatment of atrial arrhythmias, and in particular atrial fibrillation, is therefore an important aspect of the management of patients with heart failure. This review describes the incidence and possible predictors of AF and other atrial arrhythmias in patients with heart failure and discusses the feasibility of primary prevention. The evidence for the management of atrial fibrillation in heart failure is systematically reviewed and the strategies of rate versus rhythm control discussed in light of the prevailing evidence.

Effects of diltiazem and esmolol on cycle length and spontaneous conversion of atrial fibrillation

BACKGROUND

Calcium channel blocking agents have been shown to prolong the duration of atrial fibrillation. This study compared the effects of intravenous diltiazem and esmolol on the cycle length and conversion rate of pacing-induced atrial fibrillation.

METHODS AND RESULTS

In 41 adults without structural heart disease, atrial fibrillation was induced by rapid atrial pacing. After 3 minutes, either diltiazem (n = 13), esmolol (n = 15), or saline (n = 13) was infused. In the diltiazem group, the atrial fibrillation cycle length shortened by a mean of 43 milliseconds and became significantly shorter than in the control group, while the atrial fibrillation cycle length in the esmolol group did not change. Spontaneous termination of atrial fibrillation occurred significantly less often in the diltiazem group (23%) than in the esmolol (67%, P < 0.05) or placebo groups (77%, P = 0.01).

CONCLUSIONS

Intravenous diltiazem shortens the atrial fibrillation cycle length and lowers the probability of spontaneous conversion of recent-onset atrial fibrillation to sinus rhythm. These results suggest that the use of diltiazem for acute rate control may unwittingly prolong the duration of recent-onset atrial fibrillation.

Diltiazem to treat sinus tachycardia in critically ill patients: a four-year experience

OBJECTIVES

To determine whether an intravenous infusion of the calcium channel blocker diltiazem was effective and safe in treating sinus tachycardia in critically ill adult patients with contraindications to beta-blockers or in whom beta-blockers were ineffective.

DESIGN

Retrospective chart review.

SETTING

University medical center.

PATIENTS

The records of 171 surgical intensive care unit patients with sinus tachycardia treated with intravenous diltiazem were evaluated.

INTERVENTIONS

In all patients with sinus tachycardia (heart rate >100 beats/min), heart rate control with intravenous diltiazem was attempted after adequate intravascular volume expansion, pain, and anxiety control. In all patients, beta-blockade either was contraindicated or (in 7%) had failed. Intravenous diltiazem was administered as a slow 10-mg bolus dose (0.1-0.2 mg/kg ideal body weight), and then an infusion was started at 5 or 10 mg/hr and increased up to 30 mg/hr, as needed, to decrease heart rate to <100 beats/min. Variables retrospectively collected included demographic data, preinfusion blood pressure, mean arterial pressure, heart rate, and preinfusion pressure-rate quotients (pressure-rate quotient = mean arterial pressure / heart rate). Intravenous bolus dose, when given, and diltiazem infusion rate and time necessary to achieve the target heart rate also were recorded. The lowest heart rate recorded within 24 hrs from the initiation of the infusion and the time necessary to achieve the lowest heart rate after beginning the infusion were recorded.

MEASUREMENTS AND RESULTS

Of 171 patients studied, 97 (56%) were classified as responders. Multiple linear regression suggested that response could be predicted by age, pressure-rate quotients, baseline mean arterial pressure, and central nervous system failure. In the responders, a heart rate <100 beats/min was achieved in an average of 2 hrs, at a mean diltiazem infusion of 13.3 mg/hr. The lowest rate reached by the responders in a 24-hr period averaged 86 beats/min and was achieved in 4.8 hrs with a mean infusion rate of 14.8 mg/hr. Both target and lowest rate values were statistically different from baseline heart rate.

CONCLUSION

Diltiazem was effective in achieving short-term control of heart rate in 56% of the patients, virtually without adverse effects, where beta-blockade was contraindicated or ineffective.

Electrophysiologic effects of a novel selective adenosine A1 agonist (CVT-510) on atrioventricular nodal conduction in humans

BACKGROUND

CVT-510, N-(3(R)-tetrahydrofuranyl)-6-aminopurine riboside, is a selective A(1)-adenosine receptor agonist with potential potent antiarrhythmic effects in tachycardias involving the atrioventricular (AV) node. This study, the first in humans, was designed to determine the effects of CVT-510 on AV nodal conduction and hemodynamics.

METHODS AND RESULTS

Patients in sinus rhythm with normal AV nodal function at electrophysiologic study (n = 32) received a single intravenous bolus of CVT-510. AH and HV intervals were measured during sinus rhythm and during atrial pacing at 1, 5, 10, 15, 20, 30, 45, and 60 minutes after the bolus. Increasing doses of CVT-510 (0.3 to 10 microg/kg) caused a dose-dependent increase in the AH interval. At 1 minute, a dose of 10 microg/kg increased the AH interval during sinus rhythm from 93 +/- 23 msec to 114 +/- 37 msec, p = 0.01 and from 114 +/- 31 msec to 146 +/- 44 msec during atrial pacing at 600 msec, p = 0.003). The AH interval returned to baseline by 20 minutes. CVT-510 at doses of 0.3 to 10 microg/kg had no effect on sinus rate, HV interval, or systemic blood pressure, and was not associated with serious adverse effects. At doses of 15 and 30 microg/kg, CVT-510 produced transient second/third degree AV heart block in all four patients treated. One of these patients also had a prolonged sedative effect that was reversed with aminophylline.

CONCLUSIONS

CVT-510 promptly prolongs AV nodal conduction and does not affect sinus rate or blood pressure. Selective stimulation of the A(1)-adenosine receptor by CVT-510 may be useful for immediate control of heart rate in atrial fibrillation/flutter and to convert paroxysmal supraventricular tachycardia to sinus rhythm, while avoiding vasodilatation mediated by the A(2)-adenosine receptor, as well as the vasodepressor and negative inotropic effects associated with beta-adrenergic receptor blockade and/or calcium channel blockers.

The use of diltiazem for treating rapid atrial fibrillation in the out-of-hospital setting

STUDY OBJECTIVE

We sought to evaluate the use of intravenous diltiazem for treatment of rapid atrial fibrillation or flutter (RAF) in the out-of-hospital setting.

METHODS

This study is a retrospective review of data with historical control subjects. Data were drawn from out-of-hospital patients reported to a statewide paramedic system who presented with atrial fibrillation or flutter and a ventricular response rate (VRR) of 150 beats/min or greater. The intervention (diltiazem) group included patients who received diltiazem during a 9-month period in 1999. The control group included patients from 1998 who did not receive diltiazem. Patients who were intubated or underwent cardioversion were omitted. Therapeutic response was defined as the occurrence of change to sinus rhythm, reduction of VRR to 100 beats/min or less, or reduction of baseline VRR by 20% or greater. Data were analyzed by using the chi(2) test, the Student's t test, and odds ratios (ORs). A Bonferroni adjusted P value of.005 was used to define statistical significance.

RESULTS

Forty-three patients receiving diltiazem and 27 control subjects were included in the study. The mean total diltiazem dose was 19.8 mg (95% confidence interval 17.8 to 21.8). The diltiazem and control groups did not significantly differ with respect to age; sex; history of atrial fibrillation; prior use of digitalis, beta-blockers, or calcium channel blockers; concurrent out-of-hospital therapies; or baseline VRR or systolic blood pressure (P =.09 to 1.00). The difference in VRR reduction between the diltiazem and control groups was 38 beats/min (95% confidence interval 24 to 52); this difference was statistically significant (P <.001). The mean percentage reduction of VRR in the diltiazem group was -33.1%. The difference in systolic blood pressure change between the diltiazem and control groups was not statistically significant (P =.17). The diltiazem group had a higher prevalence of achieving VRR reduction to 100 beats/min or less than did the control group (OR 22.6; P <.001), of achieving a VRR reduction of 20% or greater (OR 19.3; P <.001), and of achieving overall therapeutic response (OR 19.3; P <.001). Few changed to sinus rhythm in either group (estimated OR 6.3; P =.15). No patients in the diltiazem group required treatment for hypotension, endotracheal intubation, resuscitation from cardiac arrest, or emergency treatment of unstable dysrhythmias.

CONCLUSION

The effects of diltiazem on RAF can be appreciated within the constraints of the out-of-hospital environment. Diltiazem should be considered as a viable field therapy for rate control of RAF.

Intravenous antiarrhythmic agents

Intravenous antiarrhythmic drugs can be used as diagnostic tools; for example, adenosine can be used to reveal the underlying rhythm in narrow QRS tachycardia. Newer class III antiarrhythmic agents, like ibutilide and dofetilide, are effective at the conversion of acute atrial fibrillation; however, electrical cardioversion is still the most effective method for restoration of sinus rhythm in persistent atrial fibrillation. Lidocaine and bretylium in the treatment and prevention of ventricular tachyarrhythmia are de-emphasized because of inefficacy, safety concerns (lidocaine), or shortage of drug (bretylium). Procainamide is effective for stable ventricular tachycardia, and amiodarone is effective in the treatment of shock-refractory ventricular fibrillation. Adrenergic blockade is likely important in the management of tachyarrhythmias, particularly in electrical storm, but more data will be necessary to establish its role.

Antidysrhythmics. Emergent

The emergent treatment of dysrhythmias in the ED continues to evolve. Classic medications such as bretylium and lidocaine are given with newer drugs like amiodarone, ibutilide, and sotalol. Studies in progress will examine their efficacy in the ED. The emergency physician must keep abreast of the growing body of literature.

Continuous intravenous diltiazem infusion for short-term ventricular rate control in children

Intravenous diltiazem was administered to 10 pediatric patients with primary atrial tachyarrhythmias with rapid ventricular response. Rapid, consistent, and safe temporary ventricular rate control was obtained in all patients given this medication.

Management of arrythmias

The management of arrhythmias in elderly patients with congestive heart failure, including atrial fibrillation, ventricular tachyarrhythmias, and bradyarrhythmias, is described. Patients with atrial fibrillation can be treated with rate control anticoagulation for stroke prevention or by attempt at cardioversion and maintenance of sinus rhythm. Elderly patients remaining in atrial fibrillation benefit from anticoagulation provided that no contraindication exists. In patients surviving malignant ventricular arrhythmias, defibrillator implantation is beneficial in elderly patients with heart failure. Prognosis and treatment of nonsustained arrhythmias depends on the presence of underlying cardiac abnormalities. In the healthy elderly population, treatment is not indicated. In patients with coronary artery disease, decreased ejection fraction, and nonsustained ventricular tachycardia, electrophysiology can further stratify risk, and defibrillator implantation can improve survival if arrhythmias are induced. This benefit is as great in elderly patients as in younger patients. Symptomatic bradycardias are increasingly common with advancing age. Symptoms are improved with pacing, with maximum benefit from physiologic rather than ventricular pacing. Although the elderly population poses a unique challenge when faced with arrhythmias, an active approach not only saves lives but also reduces morbidity.

The Management of Atrial Fibrillation in the ICU

Atrial tachyarrhythmias are the most frequent arrhythmias occurring in ICU patients, being particularly common in patients with cardiovascular and respiratory failure. Unlike ambulatory patients in whom atrial fibrillation/flutter (AF) is likely to be short lived, in the critically ill these arrhythmias are unlikely to resolve until the underlying disease process has improved. Urgent cardioversion is indicated for hemodynamic instability. Treatment in hemodynamically stable patients includes correction of treatable precipitating factors, control of the ventricular response rate, conversion to sinus rhythm, and prophylaxis against thromboembolic events in those patients who remain in AF. Diltiazem is the preferred agent for rate control, while procainamide and amiodarone are generally considered to be the antiarrhythmic agents of choice.