Natural Ischaemic Preconditioning Before First Myocardial Infarction

Study Overview
=================
Brief Summary
-----------------
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.

Official Title
-----------------
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

Conditions
-----------------
Myocardial Infarction, Angina Pectoris, Coronary Heart Disease, Peripheral Arterial Disease, Cerebrovascular Disease

Participation Criteria
=================
Eligibility Criteria
-----------------
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.

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| MI without ischaemic preconditioning<br>Myocardial infarction unheralded by any previous cardiovascular disease diagnosis and without symptoms of chest pain in the previous 90 days. | |
| MI with longstanding disease<br>Patients with myocardial infarction who have had diagnosed atherosclerotic disease for longer than 90 days preceding infarct. | |
| MI with only chest pain<br>Patients with chest pain in the 90 days preceding MI, but with no prior atherosclerotic disease diagnoses. | |
| MI with disease and chest pain<br>Myocardial infarction occurring with previously diagnosed atherosclerotic disease of longer than 90 days' duration, but with chest pain in 90 days preceding infarct. | |

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Recurrent myocardial infarction | Myocardial infarction occurring thirty or more days after the study start date. | Up to seven years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Coronary mortality | Coronary mortality, using ONS mortality statistics (ICD-10 codes I20-I25) | Up to seven years | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Myocardial infarction, Ischaemic preconditioning, Myocardial Ischaemia National Audit Project, General Practice Research Database, Hospital Episode Statistics, Office for National Statistics