Current guidelines on the management of stable coronary artery disease from the EU and US both recommend β-blockers and calcium channel blockers should be used for the relief of symptoms. [1, 2] However, EU guidelines recommend both β-blockers and calcium channel blockers as first-line treatment whereas the US guidelines only recommend calcium channel blockers when β-blockers ‘are contraindicated or cause unacceptable side effects.’ 
Furthermore, there is little data available on the prognostic effect of these drugs. Therefore CLARIFY – the prospective observational Longitudinal Registry oF patients with stable coronary artery disease – aimed to fill this knowledge gap.
This large-scale clinical trial took place across 45 countries and involved 2898 physicians, who each consecutively enrolled 10 to 15 patients. Of these, 22006 received β-blockers and 22004 calcium channel blockers. Inclusion criteria included prior myocardial infarction (MI) >3 months, and/or prior revascularisation >3 months, proven symptomatic MI, and angiographic coronary stenosis >50%, and the primary outcome was all-cause death or MI.
Researchers observed that after 5-years of follow up, there was no significant difference in the rates of all-cause mortality or MI in both the β-blocker and calcium channel blocker groups. Furthermore, there was a significant reduction in the primary end-point in patients who had experienced an MI in the previous year, compared to those whose MI occurred after 1 year – in which case there were no benefits seen with the use of β-blockers. There were no differences in primary end-point in the calcium channel blocker group, regardless of the time since the MI. 
The take-home message from the presentation at the ESC 2018 was that “β-blockers should be preferentially used in the first year following MI,” and although both β-blockers and calcium channel blockers should still be used for symptom relief in stable CAD, “mortality benefits should not be assumed.”
- 2013 ESC Guidelines on the Management of Stable Coronary Disease
- 2012 ACCF/AHA/ACP/AAB/PCNA/SCAI/STS Guideline for the Diagnosis and Management of Patients with Stable Ischaemic Heart Disease