A Cochrane review [Abstract] 1 included 14 studies with a total of 1 110 subjects. In most of the studies, hawthorn was used as an adjunct to conventional treatment. 10 trials including 855 patients with chronic heart failure (New York Heart Association classes I to III) provided suitable data for meta-analysis. For the physiologic outcome of maximal workload, treatment with hawthorn extract was more beneficial than placebo (WMD (Watt) 5.35, 95% CI 0.71 to 10.00, P < 0.02, n = 380). Exercise tolerance was significantly increased by hawthorn extract (WMD (Watt x min) 122.76, 95% CI 32.74 to 212.78, n = 98). The pressure-heart rate product, an index of cardiac oxygen consumption, also showed a beneficial decrease with hawthorn treatment (WMD (mmHg/min) -19.22, 95% CI -30.46 to -7.98, n = 264). Symptom score (shortness of breath and fatigue) improved significantly with hawthorn treatment as compared with placebo (WMD -5.47, 95% CI -8.68 to -2.26, n = 239). No data on relevant mortality and morbidity such as cardiac events were reported, apart from one trial, which reported deaths (three in active, one in control) without providing further details. Reported adverse events were infrequent, mild, and transient; they included nausea, dizziness, and cardiac and gastrointestinal complaints.
Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment and inadequate intention-to-treat adherence) and by indirectness (important long-term clinical outcomes such as cardiac death not reported)
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