Background: Acute coronary syndrome (ACS) includes acute myocardial infarction and unstable angina. ACS is common and may prove fatal. Hyperbaric oxygen therapy (HBOT) will improve oxygen supply to the threatened heart and may reduce the volume of heart muscle that will perish. The addition of HBOT to the standard treatment may reduce death rate and other major adverse outcomes.
Objectives: To assess the benefits and harms of adjunctive HBOT for treating ACS.
Search strategy: We searched the following from inception to November 2004: CENTRAL, MEDLINE, EMBASE, CINAHL, DORCTHIM, and references from selected articles. Relevant journals were handsearched and researchers in the field contacted.
Selection criteria: Randomised studies comparing the effect on ACS of regimens that include HBOT with those that exclude HBOT.
Data collection and analysis: Three reviewers independently evaluated the quality of trials using the guidelines of the Cochrane Handbook and extracted data from included trials.
Main results: Four trials with 462 participants contributed to this review. There was a trend towards, but no significant decrease in, the risk of death with HBOT (relative risk (RR) 0.64, 95% CI 0.38 to 1.06, P=0.08). There was evidence from individual trials of reductions in the risk of major adverse coronary events [MACE] (RR 0.12, 95% CI 0.02 to 0.85, P=0.03; NNT 4, 95% CI 3 to 10) and some dysrhythmias following HBOT (RR 0.59, 95% CI 0.39 to 0.89, P=0.01; NNT 6, 95% CI 3 to 24), particularly complete heart block (RR 0.32, 95%CI 0.12 to 0.84, P=0.02), and that the time to relief of pain was reduced with HBOT (Weighted Mean Difference [WMD] 353 minutes shorter, 95% CI 219 to 488, P<0.0001). One trial suggested a significant incidence of claustrophobia in single occupancy chambers of 15% (RR of claustrophobia with HBOT 31.6, 95%CI 1.92 to 521, P=0.02).
Authors' conclusions: For people with ACS, individual small trials suggest the addition of HBOT reduced the risk of Major Adverse Cardiac Events, some dysrrhythmias, and reduced the time to relief from ischaemic pain, but did not reduce mortality. In view of the modest number of patients, methodological shortcomings and poor reporting, this result should be interpreted cautiously, and an appropriately powered trial of high methodological rigour is justified to define those patients (if any) who can be expected to derive most benefit from HBOT. The routine application of HBOT to these patients cannot be justified from this review.