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From studies which first started in Sweden many years ago, the evidence for the beneficial role of β blockers in the management of heart failure is now very substantial. We have considerable data from the meta-analyses of many small trials and from the second cardiac insufficiency bisoprolol study (CIBIS II).1-3 The modern era of large randomised control trials involving β blockers really started with the US carvedilol heart failure study, in which a very substantial reduction in mortality (which was not the primary aim of the study programme) and morbidity was shown with carvedilol.4 Another study with carvedilol was the smaller Australia–New Zealand heart failure research group trial of around 300 patients following myocardial infarction.5 This showed a reduction in a composite end point of hospitalisations but focused on one aspect—the effect on left ventricular function—which suggested that it was improved by carvedilol. This effect has now become an important feature of β blocker treatment.
CIBIS II trial
The CIBIS II trial was based on the first CIBIS study, which showed a non-significant 20% reduction in mortality but a significant reduction in hospital admissions as a result of worsening heart failure.6 ,7 CIBIS II was a much larger trial, comprising a total of 2647 patients. It was the first of the very large trials with sufficient power to address all cause mortality as the primary end point. The trial was stopped prematurely because there was a highly significant difference in mortality in favour of bisoprolol.
The primary end point in this trial was all cause mortality, while the secondary end points were cardiovascular mortality, hospital admissions, and permanent withdrawal from treatment
The patients who went into the CIBIS II trial were stable and receiving angiotensin converting enzyme (ACE) inhibitors and diuretics. They were not hospital inpatients but were …