Natural Ischaemic Preconditioning Before First Myocardial Infarction

Natural Ischaemic Preconditioning Before First Myocardial Infarction: an Analysis of Prospectively Collected UK Electronic Primary Care Records Linked to the National Registry of Acute Coronary Syndromes

There is a sharp rise in the rate of coronary heart disease diagnoses and chest pain consultations in the 90 days before a first heart attack. There is some evidence that chest pain and angina symptoms in this period have a beneficial effect on heart attack outcomes in hospital and shortly after discharge. However, the available evidence is lacking in three key areas. First it is based on a retrospective patient report of symptoms after the heart attack has occurred; this means that patients are required to survive their heart attack and may make errors when reporting prior symptoms. Second, evidence for an effect on longer term outcomes, and coronary outcomes in particular (e.g. coronary death, further heart attacks) are unknown. Third, there is conflicting evidence that these effects might differ by age, in men and women, and according to treatment in hospital.

The investigators hope to address the limitations in the evidence by performing a large, prospective study of the occurrence, timing and effect of different types of symptoms and disease diagnoses occurring before heart attack.

The investigators hypothesise that prospectively collected, clinical measures of chest pain symptoms and cardiovascular diagnoses in primary care will have a beneficial effect on short term coronary mortality and may have a beneficial effect on longer term coronary outcomes.

Inclusion Criteria:

• Patients in GPRD practices which are deemed "up to standard" by GPRD criteria will be included if their practice agreed to be linked to the MINAP, HES and ONS datasets.
• Patients must have at least one year of GPRD "up to standard" registration before the date of first MI.
• Age over 18.
• First myocardial infarction occurring between 1st January 2003 and 31st December 2008, as recorded in the Hospital Episode Statistics data or the Myocardial Ischaemia National Audit Project.

Exclusion Criteria:

• Patients will be excluded if they do not fulfil one of the inclusion criteria.