Short summary

The sparse research on myocardial injury (MIJ) has shown that high levels of troponin results in a poor prognosis. More than 40% of persons over 25 years are suffering from hypertension. Hypertensive patients are at higher risk of having a cardiovascular event and have an increased risk of death. It has yet to be established what role hypertension plays in patients with MIJ, and how the systolic blood pressure (SBP) effects the patients prognosis. Therefore, the aim of this study is to determine the prognostic value of the SBP and the cause of death in patients with MIJ.

Rationale

MIJ is defined as a condition where a patient has elevated cardiac troponin (cTn) in a blood sample, without presenting any symptoms of myocardial ischemia. Elevated cTn combined with symptoms of myocardial ischemia is defined as a myocardial infraction (MI).

The mechanisms underlying MIJ are complex and not fully clarified. An association between MIJ and different cardiac or non-cardia diseases exists.

Two Danish cohort studies based on the DEF-AMI database, describe the characteristics of patients with MIJ and the prognostic significance of having MIJ associated with to different cardiac and non-cardiac conditions. In these papers it is noted that patients with MIJ present with a lower SBP or that fewer of the patients have been diagnosed with hypertension when compared with patients with MI.

One other study found that patients with MIJ have a similar risk of death and readmissions as patients suffering from type-1 and type-2 MI.

The prognostic value of cTn has been investigated in studies in relation to both diastolic- and SBP values. In both settings, patients with elevated cTn values had an increased cardiovascular risk. In the present study, we investigate the association between the SBP, cTn values and the long term prognosis of patients with myocardial injury.

The aims of this study are to 1) Identify and categorize patients with MIJ into groups with high, low or normal SBP. 2) Assess the all-cause mortality in the individual SBP groups. 3) Compare the mortality between the groups. 4) Investigate the SBP as a prognostic factor. 5) Investigate the cause of death within the individual SBP groups.

Description of the cohort

The original DEF-AMI cohort consists of patients from the local catchment area of Odense University Hospital. In a 1-year period (2010-2011), all patients who had a cardiac troponin I (cTnI) measured at any of the hospitals clinical departments, were possible study subjects.

Within 24 hours after the initial cTnI sampling, patients had a supplementary history taken, focusing on symptoms, clinical characteristics, and comorbidity. Only patients' comorbidity that could be validated in the patients' medical records or by the list of current medication, were registered. Patients aged less than 18 years were excluded, and a patient could only be included once.

The original cohort consists of 3762 patient. In total 1577 patients had an elevated cTnI. A group of 488 patients were diagnosed with MI and were excluded from this study. Further 133 patients were excluded based on missing systolic blood pressure values.

Therefore our final cohort consist of 956 patients, who all were diagnosed as having MIJ. 

Data and biological material

The study cohort is a sub-group of patients from the DEF-AMI database. From this database we will extract all baseline information on the patients of relevance.

From the Danish CPR register; status on death or alive, if the patient lives in DK or not, sex, birthdate and the date of death will be available.

From the Cause of death register (DAR); date of death, age, sex, primary cause of death, secondary cause of death and a list of 49 diagnosis groups classifying the cause of death can be identified.

Collaborating researchers and departments

Department of Cardiology, Odense University Hospital

• Professor Hans Mickley
• Lotte Saaby, PhD

OPEN Odense Patient data Explorative Network, Odense University Hospital