Guidelines by employing Fuzzy-Logic based software

Supporting the implementation of Acute Myocardial Infarction Treatment Guidelines by employing Fuzzy-Logic based software B. Spyropoulos, P. Sochos, S. Kalibaki

Technological Educational Institution of Athens Medical Instrumentation Technology Department, 12210 Athens, Greece Background information: Only 10-15% of all patients admitted to the Emergency Room with chest pain develops acute myocardial infarction (AMI). The early diagnosis of AMI has to be sensitive, that patients with myocardial infarction can be treated with thrombolytic therapy, and yet so specific, that patients with chest pain, but without underlying myocardial infarction, are not unnecessarily exposed to the risk of such a treatment. The diagnosis of AMI is based on the detection of at least two out of three infarction-specific findings: * Chest pain >20 min resistant to Nitro derivatives. * Infarction-specific ECG alteration in at least two leads of the standard 12-lead ECG. * Increased activity of "cardiac" enzymes. The purpose of the project was the development of software, supporting "cardiac" enzyme evaluation, during the implementation of typical Acute Myocardial Infarction Treatment Guidelines, based on the employment of Fuzzy-Logic rules. Methodology: The system is based on the fact that during an acute myocardial infarction, there is an increase of the concentration of certain, so called cardiac enzymes, which at some point after the onset of the chest pain, reaches a peak and passes on to a normalization phase. The most appropriate enzymes comprise of Aspartate Aminotransferase (AST), Lactate Dehydrogenase (LDH), 2-Hydroxyburate Dehydrogenase (HBDH), Creatine Kinase (CK), Cardiac Troponin I (cTnI), Cardiac Troponin T (cTnT), Glycogen Phosphorylase Isoenzyme BB (GPBB) and the Heart Fatty Acid Binding Protein (H-FABP). The most relevant features of the above mentioned enzymes, i.e. the Molecular Weight (MW), the reference concentration (Ref.), the Biological Half-life (HL), the Increase time (Incr)., the Peak time (Peak) and the Normalization time (N) are displayed in Table 1. By inserting the measured activity values and the corresponding sampling times, of at least one and up to maximum ten specific enzymes, after the onset of the chest pain, the system calculates repetitively AMI risk probabilities for "suspicious" patients in the Observation Ward of an Emergency Department. Reliable reported', average diagnostic sensitivities, of commercially available parameters, are taken into account, and they are

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accordingly weighed in the employed algorithm. The degree of certainty P, for the occurrence of an acute myocardial infarction, is calculated, step by step, for each enzyme concentration C', exceeding the "normal" interval [C' min, C max] by the following equation, where Pi, and Pi2 enzyme specific constants: K1 C' /(Ci max+C' min) - Pi,

C'