ABSTRACT
To study the factors determining the positivety of late potentials and its prevalence in unstable angina, fifty unstable angina patients together with a sex and age matched twenty stable angina patients serving as control were included in this study. All were subjected to careful history taking and clinical examination, laboratory blood analysis; twelve leads resting surface ECG; echo-Doppler study; 24-hours Holterniortitoring and signal averaged ECG [SAECG] namely filtered QRS complex duration, root of the mean square of signal amplitude in the last 40 msec of the filtered QRS and the duration of terminal filtered low signal amplitude [LAS] with frequency amplitude<40 uv. Echo-Doppler; Holter monitoring and SAECG were repeated two weeks later for the unstable angina patients. Exercise treadmill was done to confirm the diagnosis of stable angina patients. In the present study the incidence of positive LPs was 24% on admission and was significantly reduced to 14% after 2 weeks of medical therapy in unstable angina patients. However, non of the stable angina patients had positive LPs. All the parameters of SAECG were significantly higher in the unstable angina patients. Sex and age had no effect on the incidence of LPs, inferior ischemia had significantly higher positive LPs than anterior ischemia [55% vs 33%/. Holter-reported ischaemic episodes and echo-reported regional wall motion abnormalities were significantly positively correlated with positive LPs. The presence of left ventricular systolic and diastolic dysfunction significantly increase the incidence of positive LPs and their improvement significantly reduce the incidence of positive LPs Positive LPs was recorded in 24% of patients with unstable angina Left ventricular systolic and diastolic dysfunction and the frequency of ischaemic episodes showed significant positive correlation with the incidence of positive LPs Medical therapy significantly reduced the incidence of positive LPs