Prediction and stratification of the future cardiovascular arrhythmic events: signal averaged electrocardiography versus ejection fraction.

Cardiac arrhythmias as cause of sudden cardiac death remains an important public health problem. The availability of effective treatment in terms of the implantable defibrillator makes it critical to identify individuals at risk. An essential step in this process is the use of noninvasive techniques to screen patients and identify those at risk. The detection of ventricular late potential using the SAECG as a non-invasive technique is being explored for this purpose. The objective of the study was to stratify the future cardiovascular events including life threatening cardiac arrhythmias, in different cardiac diseases through positive and negative predictive values of SAECG and comparing with EF% another mechanical determinant. The study was conducted on 152 subjects selected from the OPD and admitted case of the New Civil Hospital and Govt. Medical College, Surat; between 25 to 75 years of age group, from August 2001 to June 2004. 80 healthy subjects free from any major acute/chronic illness were selected as a control using our own normative values for SAECG. The statistical analysis was performed using SPSS package. The results obtained were analyzed for significance by using Chi square and Independent 't' test. When we compared the cardiac arrhythmic events on 6 month follow-up study, based on SAECG and EF% separately we found that negative predictive value of SAECG was more (99.1%) than negative predictive value of EF% (93.6%). However positive predictive values for cardiac arrhythmic events of SAECG were less (28.9%) compare to EF% (42.9%). When both the parameters SAECG and EF% are considered together the negative as well as positive predictive values of these tests were quite high (100% and 50% respectively). In this study conducted on 152 patients we found that SAECG and EF% together were an accurate predictor of the cardiac arrhythmic events in terms of positive and negative predictive value while SAECG or EF% alone were not. However SAECG has got a more negative predictive value compare to EF%. In this study SAECG compared favorably or even better than EF% for risk stratification. SAECG and EF% together (and not separately) may be considered as a better investigational tool to stratify future cardiovascular arrhythmic events.