The Cardiovascular disease research using Linked Bespoke studies and Electronic Records (CALIBER) e-health database was the data resource for this study. CALIBER links patient records from four different data sources: Clinical Practice Research Database (CPRD), MINAP (Myocardial Ischaemia National Audit Project registry) Hospital Episodes Statistics (HES), the Office for National Statistics (ONS).

This study is part of the CALIBER (Cardiovascular disease research using linked bespoke studies and electronic records) programme funded over 5 years from the NIHR and Wellcome Trust. The central theme of the CALIBER research is linkage of the Myocardial Ischaemia National Audit Project (MINAP) with primary care (GPRD) and other resources. The overarching aim of CALIBER is to better understand the aetiology and prognosis of specific coronary phenotypes across a range of causal domains, particularly where electronic records provide a contribution beyond traditional studies. CALIBER has received both Ethics approval (ref 09/H0810/16) and ECC approval (ref ECC 2-06(b)/2009 CALIBER dataset).

Inclusion Criteria:

• Aged >=30 years at study entry ->=1 year registration prior to the 'index date'

Exclusion Criteria:

• Free from previous atherosclerotic events
• No heart rate measurement after their 'index date' of eligibility to entry the study

An open cohort of 2,23 million people covering approximately 5% of the UK population was drawn from registrants to 225 GP practices who consented to data linkage.