Prophylactic lidocaine for postoperative coronary artery bypass patients, a double-blind, randomized trial

Lidocaine as an anti-arrhythmic drug: Are there any indications left?

Lidocaine is classified as a class Ib anti-arrhythmic that blocks voltage- and pH-dependent sodium channels. It exhibits well investigated anti-arrhythmic effects and has been the anti-arrhythmic of choice for the treatment of ventricular arrhythmias for several decades. Lidocaine binds primarily to inactivated sodium channels, decreases the action potential duration, and increases the refractory period. It increases the ventricular fibrillatory threshold and can interrupt life-threatening tachycardias caused by re-entrant mechanisms, especially in ischemic tissue. Its use was pushed into the background in the era of amiodarone and modern electric device therapy. Recently, lidocaine has come back into focus for the treatment of acute sustained ventricular tachyarrhythmias. In this brief overview, we review the clinical pharmacology including possible side effects, the historical course, possible indications, and current Guideline recommendations for the use of lidocaine.

Cardioprotective Effect of Anesthetics: Translating Science to Practice

Cardiovascular diseases are the number one cause of mortality in the world, particularly among the aging population. Major adverse cardiac events are also a major contributor to perioperative complications, affecting 2.6% of noncardiac surgeries and up to 18% of cardiac surgeries. Cardioprotective effects of volatile anesthetics and certain intravenous anesthetics have been well-documented in preclinical studies; however, their clinical application has yielded conflicting results in terms of their efficacy. Therefore, better understanding of the underlying mechanisms and developing effective ways to translate these insights into clinical practice remain significant challenges and unmet needs in the area. Several recent reviews have focused on mechanistic dissection of anesthetic-mediated cardioprotection. The present review focuses on recent clinical trials investigating the cardioprotective effects of anesthetics in the past five years. In addition to highlighting the main outcomes of these trials, the authors provide their perspectives about the current gap in the field and potential directions for future investigations.

Is intravenous lidocaine protective against myocardial ischaemia and reperfusion injury after cardiac surgery?

A best evidence topic was constructed using a described protocol. The three-part question addressed was: In patients undergoing cardiac surgery, does intravenous lidocaine exert a cardioprotective effect against postoperative myocardial ischaemia and reperfusion injury? Using the reported search, 461 papers were found, of which 5 studies represented the best evidence to answer the question. In 3 studies, lidocaine was associated with a postoperative fall in biomarkers of myocardial injury. An additional study lacked power, but the difference in biomarkers was marginally non-significant with a trend in favour of lidocaine. A final study evaluating ischaemic changes on continuous and 12 lead ECG found no benefit with lidocaine. The limited evidence suggests that lidocaine may be cardioprotective, although no study has demonstrated improvement in clinical outcomes. Furthermore, all trials were small studies with a multitude of dosing regimens in heterogenous patient populations. There is insufficient data to correlate dose with effect and not all studies measured plasma lidocaine concentration. The narrow therapeutic index and our current evidence base does not support lidocaine prophylaxis.

Postoperative arrhythmias after cardiac surgery: incidence, risk factors, and therapeutic management

Arrhythmias are a known complication after cardiac surgery and represent a major cause of morbidity, increased length of hospital stay, and economic costs. However, little is known about incidence, risk factors, and treatment of early postoperative arrhythmias. Both tachyarrhythmias and bradyarrhythmias can present in the postoperative period. In this setting, atrial fibrillation is the most common heart rhythm disorder. Postoperative atrial fibrillation is often self-limiting, but it may require anticoagulation therapy and either a rate or rhythm control strategy. However, ventricular arrhythmias and conduction disturbances can also occur. Sustained ventricular arrhythmias in the recovery period after cardiac surgery may warrant acute treatment and long-term preventive strategy in the absence of reversible causes. Transient bradyarrhythmias may be managed with temporary pacing wires placed at surgery, but significant and persistent atrioventricular block or sinus node dysfunction can occur with the need for permanent pacing. We provide a complete and updated review about mechanisms, risk factors, and treatment strategies for the main postoperative arrhythmias.

New treatments for perioperative cardiac arrhythmias

Cardiac arrhythmias remain a major source of morbidity, mortality, and prolonged postoperative hospital stay in surgical patients. Recent studies in patients experiencing out-of-hospital cardiac arrest have expanded our knowledge in the management of cardiac arrhythmias. Future advances require additional studies focused on the unique proarrhythmic substrates in surgical patients, to provide a clear rationale for antiarrhythmic drug therapy in the perioperative period.

Cardiac surgery: postoperative arrhythmias

Arrhythmias are common after surgery, particularly after cardiac surgery. Atrial fibrillation is the most common arrhythmia encountered postoperatively, although ventricular arrhythmias and conduction disturbances can also occur. Older age is the most consistent predictor of postoperative atrial arrhythmias. beta-adrenergic blockers, amiodarone, and sotalol are the most effective at preventing postoperative atrial fibrillation. Sustained ventricular arrhythmias in the recovery period after cardiac surgery warrant aggressive therapy, usually with an implantable cardioverter-defibrillator in the absence of reversible causes. Postoperative, nonsustained ventricular tachycardia in the setting of left ventricular dysfunction and ischemic coronary disease also usually warrants risk stratification and possible treatment, often with electrophysiologic testing and implantation of an implantable cardioverter-defibrillator, if sustained ventricular arrhythmias are induced. Transient bradyarrhythmias may be managed with temporary pacing wires placed at surgery, but significant and persistent atrioventricular block or sinus node dysfunction can occur and indicate a need for permanent pacing.

The effects of the new antiarrhythmic E 047/1 on postoperative ischemia-induced arrhythmias in dogs

Perioperative malignant ventricular tachyarrhythmias pose an imminent clinical danger by potentially precipitating myocardial ischemia and severely compromising hemodynamics. Thus, immediate and effective therapy is required, which is not always provided by currently recommended IV drug regimens, indicating a need for more effective drugs. We examined antiarrhythmic effects of the new benzofurane compound E 047/1 on spontaneous ventricular tachyarrhythmia in a conscious dog model. One day after experimental myocardial infarction, 40 dogs exhibiting tachyarrhythmia randomly received (bolus plus 1-h infusion) E 047/1 6 mg/kg plus 6 mg x kg(-1) x h(-1), lidocaine 1 mg/kg plus 4.8 mg x kg(-1) x h(-1), flecainide 1 mg/kg plus 0.05 mg x kg(-1) x h(-1), amiodarone 10 mg/kg plus 1.8 mg x kg(-1) x h(-1), or bretylium 10 mg/kg plus 20 mg x kg(-1) x h(-1). Electrocardiogram was evaluated for number of premature ventricular contractions (PVC), normally conducted beats originating from the sinoatrial node, and episodes of ventricular tachycardia. Immediately after the bolus, E 047/1 reduced PVCs by 46% and increased sinoatrial beats from 4 to 61 bpm. The ratio of PVCs to total beats decreased from 98% to 58%. Amiodarone and flecainide exhibited antiarrhythmic effects with delayed onset. Lidocaine did not suppress PVCs significantly, and bretylium was proarrhythmic. The antiarrhythmic E 047/1 has desirable features, suppressing ischemia-induced ventricular tachyarrhythmia quickly and efficiently, and may be a useful addition to current therapeutic regimens.

IMPLICATIONS

Life-threatening arrhythmias of the heart after myocardial infarction or ischemia may be treated quickly and efficiently by the new drug E 047/1.

Does lidocaine protect the heart during coronary revascularisation?

BACKGROUND

Lidocaine has been used as the primary antiarrhythmic agent for ventricular arrhythmias during acute myocardial infarction (MI) and open heart surgery. Its cardioprotective effects have been studied in experimental settings and also during angioplastic reperfusion and coronary revascularisation. The basic mechanism of action, probably also involved with cardioprotection, has been demonstrated to be blockade of cardiac sodium channels. In this open study we investigated the contribution of continuous lidocaine infusion to cardioprotection during coronary revascularisation with blood cardioplegia.

METHODS

During coronary revascularisation with cold blood cardioplegia, a study group of 50 patients received a prophylactic lidocaine infusion for 20 h started with a bolus dose before aortic clamping; another group of 50 patients without the infusion served as a control group. Serum troponin T concentration, serum creatine kinase MB activity and electrocardiography were the main parameters recorded.

RESULTS

Serial measurement of Troponin T (P = 0.06) and CK-MB values: (P = 0.09) were slightly lower in the lidocaine group, but the differences were not statistically significant.

CONCLUSION

Lacking statistically significant evidence of improved cardioprotection, lidocaine infusion cannot be recommended as a routine treatment during coronary revascularisation.

Arrhythmias and conduction disturbances after coronary artery bypass graft surgery: epidemiology, management, and prognosis

CABG is associated with many perioperative complications, including supraventricular and ventricular arrhythmias and conduction disturbances. Atrial fibrillation occurs in < or = 40% of patients after CABG and is especially common in older patients. Although it is often benign and self-limited, it can lead to complications such as stroke. Treatment consists primarily of control of the ventricular response rate; in some cases, antiarrhythmic drugs or electrical cardioversion are needed. Anticoagulation should be considered in appropriate cases of persistent (48 to 72 hours) atrial fibrillation after initial treatment. Prophylaxis, especially with beta-blocking agents, seems to be effective and should be considered in appropriate cases. Simple ventricular arrhythmias are common after CABG and do not affect the patient's prognosis; however, sustained VT/VF occur infrequently (< 2% of patients) and carry a high mortality rate. Treatment is aimed at correcting precipitating factors (e.g., myocardial ischemia). Electrophysiologically guided drug therapy and implantation of an ICD should be considered in appropriate cases for patients who survive the initial events. Transient minor conduction disturbances are common after CABG; in some patients persistent AV block and sinus node dysfunction develop and may require treatment with permanent pacemaker.

Lidocaine prophylaxis in coronary revascularization patients: a randomized, prospective trial

Life-threatening ventricular ectopy can occur after cardiac operations. The actual incidence of ventricular ectopy and the ability to prevent it by the routine prophylactic use of lidocaine hydrochloride have not been established. We performed a double-blind, randomized, prospective trial involving 109 patients undergoing elective coronary artery revascularization. Patients received either lidocaine (n = 54) or a placebo (n = 55) after separation from bypass. A Holter monitor was affixed to each patient for subsequent review, and bedside intensive-care monitors with alarms were used for "real-time" surveillance. The code was broken when potentially malignant ventricular ectopy or side effects attributable to the study drug were noted. Three lidocaine patients and 2 placebo patients were dropped from the study because of hemodynamic instability or bleeding. Of the remaining 104 patients, the code was broken in 12 (24%) of the 51 in the lidocaine group (9 for ectopy and 3 for mental status changes) and 10 (19%) of the 53 in the placebo group (all for ectopy) (p = not significant). Twenty-four-hour Holter monitor evaluation demonstrated occasional ventricular ectopy in all patients and nonsustained ventricular tachycardia in 28% in the lidocaine group and 48% in the placebo group (p = not significant). The mean number of runs of ventricular tachycardia per patient was 0.53 in the lidocaine group and 1.6 in the placebo group (p = 0.035). There were no significant differences in terms of other ventricular ectopy, morbidity, or mortality. No ventricular fibrillation occurred in either group.(ABSTRACT TRUNCATED AT 250 WORDS)

Ventricular dysrhythmias in patients undergoing coronary artery bypass graft surgery: Incidence, characteristics, and prognostic importance

To determine the incidence and characteristics of ventricular dysrhythmias (premature ventricular contractions greater than 30/min, ventricular tachycardia greater than or equal to 3 beats, and ventricular fibrillation) and whether a relationship exists between ventricular tachycardia and myocardial ischemia in patients undergoing coronary artery bypass graft surgery, we continuously monitored 50 patients for 10 perioperative days using two-lead electrocardiography. Electrocardiographic changes consistent with ischemia were defined as a reversible ST depression greater than or equal to 1.0 mm, or ST elevation greater than or equal to 2.0 mm from baseline, lasting at least 1 minute. Ventricular dysrhythmias developed in 10% of patients preoperatively and in 16% intraoperatively before bypass surgery. The highest incidence occurred postoperatively, with ventricular dysrhythmias developing in 66% of patients (22% to 44% of patients on any postoperative day 0 to 7). Premature ventricular contractions were greater than 30/hr in 6% of patients preoperatively, in 8% intraoperatively before bypass, and in 34% postoperatively (6% to 23% of patients on any postoperative day). Twenty-nine patients (58%) developed 76 verified episodes of greater than or equal to 3 beats of ventricular tachycardia. Ventricular tachycardia occurred in 6% of patients preoperatively (four episodes), in 8% of patients intraoperatively prior to bypass (four episodes), and 54% of patients postoperatively (5% to 21% on any postoperative day). No patient developed ventricular fibrillation. All postoperative ventricular tachycardia episodes (after tracheal extubation) were asymptomatic. Postoperatively, 48% of patients developed ischemia, compared with 12% preoperatively and 10% intraoperatively before bypass surgery. Only 5 of 68 (7%) postoperative ventricular tachycardia episodes occurred within 3 hours of an ischemia episode.(ABSTRACT TRUNCATED AT 250 WORDS)