Assessment of sudden cardiac arrest incidence in patients with syncope/ ventricular arrythmias between 48th hour to 40TH day of acute coronary syndrome

ABSTRACT Aim: Sudden cardiac death (SCD) is still one of the most important complication after acute myocardial infarction (MI) in recent years despite the implementation of contemporary interventional and efficient medical treatments. It has been shown depressed left ventricular ejection fraction (LVEF) is the most significant independent risk factor after acute MI. Implantable cardioverter defibrilator (ICD) is recommended 40 days after acute MI with assessment of LVEF. Nonetheless, SCD was more frequently observed in the first month after MI. The aim of this study was to investigate correlation between ventricular arrythmias/ syncope occuring within 48th hour and 40th day of MI and SCD/ sudden cardiac arrest. Material and Method: Two hundred and sixty nine patients diagnosed with MI were enrolled in the study. 24 hour recording Holter electrocardiography (ECG) was applied to all patients between 48th hour to 40th day of MI. The number and complexity of ventricular extrasystole (VES) were assessed. According to Lown classification, classes 0, 1, 2 and 3 VES were identified as benign, classes 4a, 4b and 5 VES were identified as malignant. Malignant VES, sustained or nonsustained ventricular tachycardia (VT) and ventricular fibrilation (VF) were accepted as malignant ventricular arrythmias. Syncope was interrogated 40 days after MI. SCD or sudden cardiac arrest were defined as primary endpoint of the study. Patients were followed up to 15.75±7.09 months. Primary endpoint was interrogated at the end of the study. Results: Thirty three patients deceased during follow up including SCD in 10 patients and sudden cardiac arrest in three patients. Four patients experienced syncope between 48th hour to 40th day of MI and one of them ended up with primary endpoint. 7.7% of primary endpoint observed patients and 1.2% of other patients experienced syncope (p=0.181). Malignant ventricular arrythmias were detected in 23.1% of primary endpoint observed patients and 9.8% of other patients (p=0.142). Nonsustained VT was detected in 23.1% of primary endpoint observed patients and 2.3% of other patients (p=0.006). Nonsustained VT was not demonstrated to be an independent risk parameter by multivariate Cox and logistic regression analyses. Female sex, history of peripheral arterial disease (PAD) and heart failure (HF), inability to use beta blokers, incomplete revascularization or absence of revascularization were shown to be significant risk parameters in logistic regression analysis. Female sex, higher body mass index, history of PAD, higher heart rate in ECG, incomplete revascularization or absence of revascularization were shown to be significant risk parameters in Cox regression analysis. Conclusion: Nonsustained VT which is detected in Holter ECG between 48th hour to 40th day of MI might be used as a risk predictor for SCD or sudden cardiac arrest. It is not accurate to reach a precise decision for syncope because of insufficient event rates. Female patients with history of PAD and HF, higher heart rate in ECG, incomplete revascularization or absence of revascularization and inability to use beta blokers ought to be accepted in high risk group for SCD. Key Words: Myocardial Infarction, Syncope, Ventricular Arrythmia, Sudden Death, Sudden Cardiac Arrest