Three part question

[In patients with symptoms compatible with myocardial ischaemia] is [the use of intravenous cyclizine] associated with [increased myocardial work, morbidity, or mortality]?

Clinical scenario

A 52 year old man presents to the emergency department with a history suggestive of myocardial ischaemia. He requires intravenous opioids for pain and is feeling nauseous so you decide to give him an intravenous antiemetic. However, your consultant tells you not to use cyclizine as it can increase the heart rate, and thus myocardial oxygen demand, in already ischaemic muscle. You wonder whether this is true, or just more evidence of his eccentricity?

Search strategy

Medline 1966–Week 1, September 2005, using the OVID interface: [{exp Myocardial Infarction/or MI.mp or myocardial infarction.mp. or exp Myocardial Infarction/or exp Coronary Disease/or heart attack.mp or chest pain.mp. or exp Chest Pain/or angina.mp. or exp Angina Pectoris/or acute coronary syndrome.mp. or exp Angina, Unstable/or exp Myocardial Ischemia/or myocardial ischaemia.mp. or myocardial ischemia.mp. or ACS.mp. or exp Coronary Thrombosis/or exp Coronary Disease/or acute coronary$.mp.} AND {cyclizine.mp. or exp CYCLIZINE/or valoid.mp. or antihistamine.mp. or exp Histamine H1 Antagonists/or antihistamine$.mp.}] Limit to humans and English language; Cochrane Database of Systematic Reviews and the Cochrane Central Register of Controlled Trials: [cyclizine]

Search outcome

Medline: 70 articles found of which one was relevant to the three part question (table 1). Cochrane: 66 citations. No new papers found.

Comment(s)

Although intravenous cyclizine is used regularly as an antiemetic in patients with cardiac chest pain concerns have been expressed about its potential effects on myocardial work/ischaemia. This well controlled but small study demonstrated significant changes in haemodynamic parameters with cyclizine, which appeared to be independent of the effects of diamorphine. In theory, raised vent filling pressures and an increase in afterload described in this study and confirmed by a reduction in cardiac output could lead to reduction of coronary artery flow and increase in myocardial oxygen consumption.

The major limitation of this study is the patient group studied and whether the results can be translated to the emergency department patient. In addition the effects of other antiemetics have not been studied so no comparative data are available, although cyclizine, as an antihistamine, is in a different group than most other commonly prescribed antiemetics. However, as it is often difficult to predict the clinical course of a patient when first assessed, it may be advisable to avoid cyclizine as a first line antiemetic.

CLINICAL BOTTOM LINE

Cyclizine should be avoided in patients with acute coronary events.