Management of atrial fibrillation in the post-cardiac surgery setting

Dose-dependent effect of landiolol, a new ultra-short-acting β(1)-blocker, on supraventricular tachyarrhythmias in postoperative patients

BACKGROUND

β-Adrenoceptor antagonists (β-blockers) have been reported to be effective for regulation of heart rate (HR) and restoring sinus rhythm in postoperative atrial fibrillation and atrial flutter, as well as in the prevention of those arrhythmias after open-heart surgery.

OBJECTIVES

The objectives of this study were to evaluate the dose-dependent effects of landiolol, an ultra-short-acting β1-blocker, as well as the effectiveness and safety of the drug in suppressing supraventricular tachyarrhythmias (SVT) in postoperative patients.

METHODS

Landiolol was administered as a four-dose titration regimen (LL, L, M, and H doses) to postoperative patients who developed SVT. The titration sequence began with a 1-min loading infusion at a rate of 0.015 mg/kg/min, followed by a 10-min continuous infusion at 0.005 mg/kg/min (the LL dose). Infusions at progressively higher doses followed in sequence until 20 % reduction in HR was achieved. The L dose was a 1-min loading infusion at 0.03 mg/kg/min, followed by a 10-min continuous infusion at 0.01 mg/kg/min. The M dose was a 1-min loading infusion at 0.06 mg/kg/min, followed by a 10-min continuous infusion at 0.02 mg/kg/min. The H dose was a 1-min loading infusion at 0.125 mg/kg/min, followed by a 10-min continuous infusion at 0.04 mg/kg/min. The patient was then observed for 30 min to determine the cardiovascular responses to withdrawal of the medication. After completion of this follow-up period, additional maintenance infusion for up to 6 h was permitted if considered necessary by the investigator.

RESULTS

A total of 108 patients were enrolled in this study. The cumulative improvement rates (percentage of patients obtaining ≥20 % reduction in HR) were 11.4, 32.4, 63.1, and 87.3 % at the LL, L, M, and H doses, respectively, demonstrating the dose-dependent effectiveness of landiolol. Additional infusion for up to 6 h was conducted in 16 patients. HR was maintained between 95.5 and 116.8 beats/min during the maintenance period (mean 259.8 min). Landiolol was generally well tolerated, although one patient with sick sinus syndrome developed an approximately 5-s cardiac arrest.

CONCLUSIONS

The overall results, including those pertaining to patient safety, demonstrate that landiolol is effective and useful for the treatment of postoperative SVT.

Management of atrial fibrillation in critically ill patients

Atrial fibrillation (AF) is common in ICU patients and is associated with a two- to fivefold increase in mortality. This paper provides a reappraisal of the management of AF with a special focus on critically ill patients with haemodynamic instability. AF can cause hypotension and heart failure with subsequent organ dysfunction. The underlying mechanisms are the loss of atrial contraction and the high ventricular rate. In unstable patients, sinus rhythm must be rapidly restored by synchronised electrical cardioversion (ECV). If pharmacological treatment is indicated, clinicians can choose between the rate control and the rhythm control strategy. The optimal substance should be selected depending on its potential adverse effects. A beta-1 antagonist with a very short half-life (e.g., esmolol) is an advantage for ICU patients because the effect of beta-blockade on cardiovascular stability is unpredictable in those patients. Amiodarone is commonly used in the ICU setting but has potentially severe cardiac and noncardiac side effects. Digoxin controls the ventricular response at rest, but its benefit decreases in the presence of adrenergic stress. Vernakalant converts new-onset AF to sinus rhythm in approximately 50% of patients, but data on its efficacy and safety in critically ill patients are lacking.

The effectiveness and safety of landiolol hydrochloride, an ultra-short-acting β1-blocker, in postoperative patients with supraventricular tachyarrhythmias: a multicenter, randomized, double-blind, placebo-controlled study

Background

Persistent postoperative supraventricular tachyarrhythmias (SVTs) increase cardiac burden and aggravate cardiac hemodynamics. Therefore, for patients in unstable conditions after surgery, prompt and sustained control of heart rate is essential. The importance of β-adrenoceptor antagonists (β-blockers) in controlling such postoperative atrial fibrillation or atrial flutter has been established, and the usefulness of ultra-short-acting β₁-blockers with high β₁ selectivity has been suggested based on their safety and efficacy under such circumstances.

Objectives

Our objectives were to evaluate the effectiveness and safety of landiolol hydrochloride, an ultra-short-acting β₁-selective blocker, in the treatment of postoperative SVT in patients with a high risk of myocardial ischemia, or in patients after highly invasive surgery, in a multicenter, randomized, double-blind, placebo-controlled, group-comparative study.

Methods

A total of 165 patients were randomly allocated to three groups and received LM or MH doses of landiolol hydrochloride or placebo. LM group: dose L (1-min loading dose at a rate of 0.03 mg/kg/min, followed by a 10-min infusion at 0.01 mg/kg/min) followed by dose M (1-min loading at a rate of 0.06 mg/kg/min, followed by a 10-min infusion at 0.02 mg/kg/min); MH group: dose M followed by dose H (1-min loading dose at a rate of 0.125 mg/kg/min, followed by a 10-min infusion at 0.04 mg/kg/min); placebo (PP) group: dose P (1-min loading dose at a rate of 0 mg/kg/min, followed by a 10-min infusion at 0 mg/kg/min) followed by another round of dose P. If the targeted heart-rate reduction was not obtained at the end of the first 10-min infusion, the higher dose was started. The primary endpoint was the percentage of patients who met the heart-rate reduction criteria (≥20 % reduction and <100 beats/min). The safety endpoint was the incidence of adverse events in each of the three groups.

Results

The percentages of patients who met the heart-rate reduction criteria (≥20 % reduction and <100 beats/min) were 0.0, 60.4, and 42.0 % in the PP, LM, and MH groups, respectively. There were significant differences in the LM and MH groups relative to the PP group, but there was no significant difference between the LM and MH groups. No significant difference was observed in the incidence of adverse events among the three groups: 29.6 % in the PP group, 45.5 % in the LM group, and 43.1 % in the MH group.

Conclusion

Landiolol hydrochloride is effective and safe for patients with postoperative SVT.

Post-operative Atrial Fibrillation - Pathophysiology, Treatment and Prevention

Atrial fibrillation occurring after cardiac surgery has been the subject of intensive research over the past decades. However, the incidence remains high, despite numerous preventive and treatment strategies. In addition, several reports show that the impact of post-operative atrial fibrillation (POAF) is high. It is an independent risk factor for mortality after several years. These findings make clear that the pathophysiology of POAF is not fully understood and POAF-associated risks to some extent might be underestimated. On the one hand, excessive triggers during the acute post operative phase after cardiac surgery might initiate AF even in atria with low vulnerability. On the other hand, many patients undergoing surgery have an atrial substrate at the time of operation promoting AF not only in the post-operative phase but also in the days and weeks thereafter. Progress in our understanding of the AF mechanisms in general has provided valuable insights into processes involved in atrial structural remodeling due to advanced age, hypertension, obesity, and congestive heart failure. These patient characteristics strongly contribute to cardiac disease, predict POAF and likely have an impact on the risk of thrombus formation in the weeks and months after cardiac surgery. For a better understanding of the mechanisms involved, it is important to not only recognize the occurrence of POAF by continuous monitoring after surgery, but also to identity the extent of atrial vulnerability to AF in these patients.

Atrial Fibrillation in the Intensive Care Setting

Atrial fibrillation (AF) is the commonest cardiac arrhythmia both in the general population and in the intensive care unit (ICU) setting. Its incidence continues to rise, affecting up to 10% of patients admitted to a general ICU and up to 50% of those admitted to a cardiac ICU. Uncontrolled AF has detrimental effects on the cardiovascular system, including heart failure, thromboembolic events, reduced quality of life and prolonged hospital stay. This article reviews the risk factors for developing AF, possible underlying mechanisms, clinical features and diagnosis, and focuses particularly on its management according to the latest guidelines with a specific focus on the ICU patient. We also discuss novel anticoagulants that will revolutionise the management of antithrombotic therapy in AF patients by replacing warfarin.