Lidocaine to prevent ventricular fibrillation in the prehospital phase of suspected acute myocardial infarction: the North-Norwegian Lidocaine Intervention Trial

Prophylactic lidocaine for myocardial infarction

BACKGROUND

Coronary artery disease is a major public health problem affecting both developed and developing countries. Acute coronary syndromes include unstable angina and myocardial infarction with or without ST-segment elevation (electrocardiogram sector is higher than baseline). Ventricular arrhythmia after myocardial infarction is associated with high risk of mortality. The evidence is out of date, and considerable uncertainty remains about the effects of prophylactic use of lidocaine on all-cause mortality, in particular, in patients with suspected myocardial infarction.

OBJECTIVES

To determine the clinical effectiveness and safety of prophylactic lidocaine in preventing death among people with myocardial infarction.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2015, Issue 3), MEDLINE Ovid (1946 to 13 April 2015), EMBASE (1947 to 13 April 2015) and Latin American Caribbean Health Sciences Literature (LILACS) (1986 to 13 April 2015). We also searched Web of Science (1970 to 13 April 2013) and handsearched the reference lists of included papers. We applied no language restriction in the search.

SELECTION CRITERIA

We included randomised controlled trials assessing the effects of prophylactic lidocaine for myocardial infarction. We considered all-cause mortality, cardiac mortality and overall survival at 30 days after myocardial infarction as primary outcomes.

DATA COLLECTION AND ANALYSIS

We performed study selection, risk of bias assessment and data extraction in duplicate. We estimated risk ratios (RRs) for dichotomous outcomes and measured statistical heterogeneity using I(2). We used a random-effects model and conducted trial sequential analysis.

MAIN RESULTS

We identified 37 randomised controlled trials involving 11,948 participants. These trials compared lidocaine versus placebo or no intervention, disopyramide, mexiletine, tocainide, propafenone, amiodarone, dimethylammonium chloride, aprindine and pirmenol. Overall, trials were underpowered and had high risk of bias. Ninety-seven per cent of trials (36/37) were conducted without an a priori sample size estimation. Ten trials were sponsored by the pharmaceutical industry. Trials were conducted in 17 countries, and intravenous intervention was the most frequent route of administration.In trials involving participants with proven or non-proven acute myocardial infarction, lidocaine versus placebo or no intervention showed no significant differences regarding all-cause mortality (213/5879 (3.62%) vs 199/5848 (3.40%); RR 1.02, 95% CI 0.82 to 1.27; participants = 11727; studies = 18; I(2) = 15%); low-quality evidence), cardiac mortality (69/4184 (1.65%) vs 62/4093 (1.51%); RR 1.03, 95% CI 0.70 to 1.50; participants = 8277; studies = 12; I(2) = 12%; low-quality evidence) and prophylaxis of ventricular fibrillation (76/5128 (1.48%) vs 103/4987 (2.01%); RR 0.78, 95% CI 0.55 to 1.12; participants = 10115; studies = 16; I(2) = 18%; low-quality evidence). In terms of sinus bradycardia, lidocaine effect is imprecise compared with effects of placebo or no intervention (55/1346 (4.08%) vs 49/1203 (4.07%); RR 1.09, 95% CI 0.66 to 1.80; participants = 2549; studies = 8; I(2) = 21%; very low-quality evidence). In trials involving only participants with proven acute myocardial infarction, lidocaine versus placebo or no intervention showed no significant differences in all-cause mortality (148/2747 (5.39%) vs 135/2506 (5.39%); RR 1.01, 95% CI 0.79 to 1.30; participants = 5253; studies = 16; I(2) = 9%; low-quality evidence). No significant differences were noted between lidocaine and any other antiarrhythmic drug in terms of all-cause mortality and ventricular fibrillation. Data on overall survival 30 days after myocardial infarction were not reported. Lidocaine compared with placebo or no intervention increased risk of asystole (35/3393 (1.03%) vs 14/3443 (0.41%); RR 2.32, 95% CI 1.26 to 4.26; participants = 6826; studies = 4; I(2) = 0%; very low-quality evidence) and dizziness/drowsiness (74/1259 (5.88%) vs 16/1274 (1.26%); RR 3.85, 95% CI 2.29 to 6.47; participants = 2533; studies = 6; I(2) = 0%; low-quality evidence). Overall, safety data were poorly reported and adverse events may have been underestimated. Trial sequential analyses suggest that additional trials may not be needed for reliable conclusions to be drawn regarding these outcomes.

AUTHORS' CONCLUSIONS

This Cochrane review found evidence of low quality to suggest that prophylactic lidocaine has very little or no effect on mortality or ventricular fibrillation in people with acute myocardial infarction. The safety profile is unclear. This conclusion is based on randomised controlled trials with high risk of bias. However (disregarding the risk of bias), trial sequential analysis suggests that additional trials may not be needed to disprove an intervention effect of 20% relative risk reduction. Smaller risk reductions might require additional higher trials.

Neuropsychiatric Side-Effects of Lidocaine: Examples from the Treatment of Headache and a Review

Lidocaine has been used in treatment of patients with refractory headache. Personal observations of neuropsychiatric toxicity in these patients led us to review our cases and the literature systematically for lidocaine side-effects, especially neuropsychiatric symptoms. In our series of 20 patients, side-effects were observed in all, the most frequent being neuropsychiatric (75%) and cardiological (50%). When reviewing published series on intravenous lidocaine use, reports of side-effects range from 0 to 100%, with neuropsychiatric symptoms being reported in 1.8–100%. Thirty-six case reports of lidocaine-induced psychiatric symptoms were also analysed. Psychiatric symptoms of toxicity were similar in most patients, despite their differing ages, pathologies, co-therapies and lidocaine dosages. In conclusion, lidocaine neuropsychiatric toxicity has a well-recognized stereotypical clinical presentation that is probably unrecognized in headache series. As lidocaine represents an emerging alternative therapy in headache, particularly in short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing, clinicians and patients should be aware of the extent of this problem.

Prophylactic lidocaine use in acute myocardial infarction: incidence and outcomes from two international trials. The GUSTO-I and GUSTO-IIb Investigators

BACKGROUND

Early meta-analyses suggested that prophylactic lidocaine use reduces ventricular fibrillation but increases mortality rates after acute myocardial infarction. We determined the frequency and effect on clinical outcomes with its use in the thrombolytic era.

METHODS AND RESULTS

We studied 43,704 patients enrolled in GUSTO-I or GUSTO-IIb who had ST-segment elevation, underwent thrombolysis, and survived at least 1 hour after enrollment. Odds ratios (OR) and confidence intervals (CI) were calculated for the risk of asystole, atrioventricular block, ventricular fibrillation, and ventricular tachycardia during hospitalization; for 24-hour, in-hospital, and 30-day mortality rates; and for 24-hour and 30-day mortality rates after adjustment for baseline predictors of death. In GUSTO-I and GUSTO-IIb, 16% and 3.5% of patients, respectively, received prophylactic lidocaine. They had a lower risk of death at 24 hours (OR 0.81, 95% CI 0.67 to 0.97) and trends toward lower odds of in-hospital death (OR 0.90, 95% CI 0.81 to 1.01) and death at 30 days (OR 0.92, 95% CI 0.82 to 1. 02). After adjustment for baseline characteristics, however, the odds of death were similar with or without lidocaine (OR 0.90 and 0. 97, respectively). Outside the United States, lidocaine was associated with higher incidences of all serious arrhythmias, but in US patients it conferred a lower likelihood of ventricular fibrillation and no increase in asystole, atrioventricular block, or mortality rates.

CONCLUSIONS

Prophylactic lidocaine use has decreased with the advent of thrombolysis, although its use may not be associated with increased mortality rates.

Searching for the evidence in pre-hospital care: a review of randomised controlled trials. On behalf of the Ambulance Response Time Sub-Group of the National Ambulance Advisory Committee

OBJECTIVES

To identify randomised controlled trials (RCTs) which evaluate aspects of pre-hospital care; to perform categorisation by theme; to compare the sensitivity and precision of the search databases.

DATA SOURCES

August 1997 updates of MEDLINE and EMBASE databases, using the Datastar online system. Papers published in 1987 or later were included, with no language restrictions.

STUDY SELECTION

A trial was eligible for inclusion if it was judged, by two independent and blinded assessors, that participants followed up in the trial were definitely or possibly assigned prospectively to one of two or more alternative forms of healthcare with random allocation or a quasi-random method of allocation.

RESULTS

The literature search retrieved 849 papers, of which 569 (67%) were in MEDLINE and 486 (57%) in EMBASE. Forty one (5%) were confirmed as reports of RCTs or quasi-RCTs, and the total number of individual trials was 38. Ten of these trials dealt with thrombolytic drugs; 14 were concerned with other drugs, 12 with equipment, and two with other interventions. Four trials were based on a sample size of more than 1000, and seven reported a statistically significant effect on mortality. All 41 papers were in EMBASE, and all but one were also in MEDLINE.

CONCLUSIONS

Evidence based policy making with respect to the organisation of pre-hospital services cannot depend on RCTs. In the current relative absence of such evidence, practitioners and decision makers must use alternative information sources. A future review could examine a broader range of literature and be based on a wider search of published and unpublished material.