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Three Part Question

[In patients with symptoms compatible with myocardial ischaemia] is [the use of iv 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- September Week 1 2005 using OVID interface
Cochrane Database of Systematic Reviews and the Cochrane Central Register of Controlled Trials:
[{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:cyclizine

Search Outcome

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

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Tan LB et al, 1988 UK	11 patients (9 male; 2 female) with severe heart failure (New York Heart Association grade 4). Patients had invasive haemodynamic monitoring. All patients were given 50 mg intravenous cyclizine, monitored for 30 min, then given 10 mg intravenous diamorphine. Parameters were measured at baseline, and 10 min and 30 min after administration of cyclizine	Observational study	Heart rate (beats/min)	99.9 at baseline; 107 at 10 min (p<0.05); 107 at 30 min	Small study in a very specific group of patients
			Right atrial pressure(mm Hg)	10.1 at baseline; 12.7 at 10 min (p<0.01); 13.1 at 30 min (p<0.01)
			Mean pulmonary artery pressure(mm Hg)	37.9 at baseline; 43.8 at 10 min (p<0.01); 43.1at 30 min (p<0.01)
			Pulmonary artery wedge pressure(mm Hg)	21.9 at baseline; 27.7 at 10 min (p<0.01); 27.0 at 30 min (p<0.01)
			Mean blood pressure (mm Hg)	82.5 at baseline; 91.5 at 10 min (p<0.01); 90.9 at 30 min (p<0.01)
			Cardiac output (l/min)	4.5 at baseline; 4.3 at 10 min; 4.1 at 30 min (p<0.01)
			Systemic vascular resistance (dyne/cm2)	1352 at baseline; 1576 at 10 min (p<0.05); 1608 at 30 min
			Change in parameters after diamorphine	All returned to within 1 SEM 10 min after diamorphine administration (except for persistent elevation of right atrial and mean pulmonary pressures)

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.

References

1. Tan LB, Bryant S, Murray RG. Detrimental Haemodynamic Effects of Cyclizine in Heart Failure Lancet 1(8585):560-1, 1988 Mar 12.