Sonny Saggar, MBBS              St. Luke’s Medical Center
Impact of cardiac catheterization on the integrity of the cardiac markers, myoglobin
and troponin-I   
         
 

Background: The ECG is non-diagnostic in more than 50% of cases of acute myocardial infarction (AMI). The importance of the clinical findings and, secondarily, cardiac marker results, cannot be underestimated. Guidelines currently exist for the use of ‘early’ and ‘definitive’ markers in ‘rule-out’ protocols, namely, myoglobin (MB) and troponin-I (cTnI). Elevations of such cardiac markers can occur after coronary artery angiography, but the range and duration of elevations have not been well-delineated. Whether these elevations are a result of AMI or lesser damage with release of myocardial proteins is not known. If this is the case, these elevations should not be attributed to AMI.

Goal: We wish to investigate the impact of coronary angiography on cardiac markers and thereby either champion or denounce their use in post-angiography presentations, such as chest pain.

Methods: Patients undergoing elective cardiac catheterization will be recruited for evaluation of the effect of the procedure on their baseline MB and cTnI levels. The standard for AMI diagnosis is as defined by World Health Organization criteria. Specific inclusion and exclusion criteria will apply to minimize confounding variables, Each patient will be consented, interviewed and examined: previous medical records will be reviewed. Pre- and post- catheterization tests will be done. Whole blood will be submitted and ECGs will be obtained at selected intervals in relation to the procedure. Specimens will be frozen and stored for analysis after patient discharge. There is no need for a comparison group, but previous stress tests may be taken into account.

Conclusions: In the event that cardiac marker elevations are noted in a significant number of electively catheterized patients, consideration will have to be given towards the application of a modified ‘rule-out MI’ protocol when faced with a recently –catheterized patient presenting with symptoms such as chest-pain.