Optimizing care for ST-elevation myocardial infarction patients: application of systems engineering

Optimizing Care for ST-elevation Myocardial Infarction Patients: Application of Systems Engineering     

Systems of care for ST-elevation myocardial infarction in India

The prevalence of coronary artery disease and ST-elevation myocardial infarction (STEMI) are increasing in India. Although recent publications have focused on improving preventive measures in developing countries, less attention has been placed on the acute management of STEMI. Recent policy changes in India have provided new opportunities to address existing barriers but require greater investment and support in the coming years.     

Acute ST-elevation myocardial infarction

Acute ST-elevation myocardial infarction (STEMI) remains the leading cause of death in industrialized countries. For many patients, a myocardial infarction is the first presentation of atherosclerotic coronary artery disease. This often results in delays in obtaining medical attention and subsequently poorer outcome, certainly because symptoms are often misinterpreted. Furthermore, a large proportion of STEMI patients die from lethal arrhythmias even before reaching medical facilities. Numerous studies during the past decades have firmly established the paradigm of achieving early, complete and sustained infarct-related artery patency. Because of a more aggressive therapy and rapid revascularization using either fibrinolysis or primary PCI, many patients do remarkably well after STEMI. Unfortunately, adherence to treatment guidelines is often suboptimal, leading to less favourable outcome. Also, more efficient care for patients with myocardial infarction has led to a rapidly growing population of patients with chronic heart failure.     

Reperfusion strategies for ST-elevation myocardial infarction

Management of ST-elevation myocardial infarction requires rapid, sustained and early restoration of flow in the infarct-related artery to minimize myocardial damage and to improve clinical outcomes. Primary percutaneous coronary intervention (PCI) is the preferred therapy but is limited by restricted availability and delays in implementation. Fibrinolytic administration is widely available but is limited by its failure to achieve Thrombolysis in Myocardial Infarction grade 3 flow in many patients, re-infarction, and intracranial hemorrhage. A combination approach to reperfusion--facilitated PCI--involves the administration of a pharmacologic agent to improve reperfusion with PCI. The evidence supporting facilitated PCI varies according to the pharmacologic regimen at this time.     

Differentiating ST-elevation myocardial infarction from nonischemic ST-elevation in patients with chest pain

Current guidelines state that patients with compatible symptoms and ST-segment elevation (STE) in ≥2 contiguous electrocardiographic leads should undergo immediate reperfusion therapy. Aggressive attempts at decreasing door-to-balloon times have led to more frequent activation of primary percutaneous coronary intervention (pPCI) protocols. However, it remains crucial to correctly differentiate STE myocardial infarction (STEMI) from nonischemic STE (NISTE). We assessed the ability of experienced interventional cardiologists in determining whether STE represents acute STEMI or NISTE. Seven readers studied electrocardiograms of consecutive patients showing STE. Patients with left bundle branch block or ventricular rhythms were excluded. Readers decided if, based on electrocardiographic results, they would have activated the pPCI protocol. If NISTE was chosen, readers selected from 12 possible explanations as to why STE was present. Of 84 patients, 40 (48%) had adjudicated STEMI. The percentage for which readers recommended pPCI varied (33% to 75%). Readers' sensitivity and specificity ranged from 55% to 83% (average 71%) and 32% to 86% (average 63%), respectively. Positive and negative predictive values ranged from 52% to 79% (average 66%) and 67% to 79% (average 71%), respectively. Broad inconsistencies existed among readers as to the chosen reasons for NISTE classification. In conclusion, we found wide variations in experienced interventional cardiologists in differentiating STEMI with a need for pPCI from NISTE.