A Cochrane review included 26 studies with a total of 1 369 subjects. Listening to music was the main intervention used, and 23 of the studies did not include a trained music therapist. Twelve studies included one music session offered before or during a cardiac procedure or both (e.g. cardiac catheterization) or within 48 hours of hospitalization for MI, 2 studies included 2 sessions offered over 2 postoperative days, 12 studies offered 3 or more sessions on consecutive days. The duration of the music sessions varied across studies.
Music interventions had a small beneficial effect on psychological distress in people with CHD (MD = -1.26, 95% CI -2.30 to -0.22; 5 studies, n=228). Listening to music had a moderate effect on anxiety in people with CHD; however results were inconsistent across studies (SMD = -0.70, 95% CI -1.17 to -0.22, statistical heterogeneity I² = 77%; 10 studies, n=353). Studies that used music interventions in people with myocardial infarction found more consistent anxiety-reducing effects of music, with an average anxiety reduction of 5.87 units on a 20 to 80 point score range (95% CI -7.99 to -3.75, I² = 53%; 6 studies, n=243). Furthermore, studies that used patient-selected music resulted in greater anxiety-reducing effects (SMD = -0.89, 95% CI -1.42 to -0.36).
Listening to music reduced heart rate (MD = -3.40, 95% CI -6.12 to -0.69; 13 studies, n=828), respiratory rate (MD = -2.50, 95% CI -3.61 to -1.39; 7 studies, n=442) and systolic blood pressure (MD = -5.52 mmHg, 95% CI - 7.43 to -3.60 mmHg; 11 studies, n=775). Studies that included 2 or more music sessions led to a small and consistent pain-reducing effect (SMD = -0.27, 95% CI -0.55 to -0.00). The results also suggest that listening to music may improve patients' quality of sleep following a cardiac procedure or surgery (SMD = 0.91, 95% CI 0.03 to 1.79; 2 studies, n=122). No strong evidence for heart rate variability and depression were found. Only one study considered hormone levels and quality of life as an outcome variable. A small number of studies pointed to a possible beneficial effect of music on opioid intake after cardiac procedures or surgery, but more research is needed to strengthen this evidence.
Comment: The quality of evidence is downgraded by study quality (inadequate or unclear allocation concealment and lack of blinding) and by inconsistency (unexplained variability in results).