Risk factors and their implication on silent myocardial ischaemia

Sixty-five cases were evaluated for silent myocardial ischaemia (SMI) by computerised treadmill test (TMT) and ambulatory electrocardiographic monitoring (AEM). There were 59 males and 6 females. The cases were divided into GP-I-stable angina (35 cases) GP-II-stable angina after myocardial infarction (15 cases) and GP-III-asymptomatic (15 cases). Age in each group ranged from 36 years to 62 years (GP-I), 40 years to 68 years (GP-II) and 36 years to 48 years (GP-III). Conventional risk factors viz. hypertension, diabetes mellitus, hyperlipidemia, smoking and family history were assessed with a view to see their implication on SMI. 43 patients (62.2%) were found to have SMI including mixed episodes. Out of these 43, TMT was positive in 29 patients (67.4%), AEM was positive in 41 patients (95.3%) and both TMT and AEM were positive in 27 patients (62.7%). Correlative analysis between risk factors and SMI revealed that higher number of was associated with not only more positive TMT and AEM test along with increased episodes of SMI but also increased degree of ST-T depression. It was also found that AEM is more sensitive than TMT (80% Vs 48%) for diagnosing SMI (SED = 9.03%), though specificity of the tests is same (93.3%).