Newly developed ST-T abnormalities on the electrocardiogram and chronologic changes in cardiovascular risk factors.

An ST-T abnormality on an electrocardiogram (ECG) is known to independently predict subsequent morbidity and mortality from cardiovascular diseases. But how ST-T abnormality develops in relation to chronologic changes in cardiovascular risk factors has not been fully discussed. Sixty-eight men whose ECG had been initially normal but who exhibited ST-T abnormality later (ST-T subjects) were identified among 21,579 apparently healthy adults who had undergone comprehensive health examinations for > 10 years. Echocardiography proved that 26 of 29 examinees among ST-T subjects had left ventricular hypertrophy. Antihypertensive drugs were given to 26 of the ST-T subjects. Their cardiovascular risk factors were chronologically reviewed from 10 years before the onset of definite ST-T abnormality, and were compared with those of 68 men whose ECG had remained consistently normal for 10 years (controls). Mean values of systolic and diastolic blood pressure gradually increased over 10 years (from 127/78 to 144/84 mm Hg) among ST-T subjects, but showed little change (from 122/76 to 124/77 mm Hg) during the same period in controls. The time course of blood pressure over 10 years was similar in ST-T subjects, irrespective of final blood pressure level. Mean serum cholesterol and glucose increased over 10 years in both ST-T and control subjects. Uric acid decreased over 10 years (from 6.1 to 5.6 mg/dl) only in ST-T subjects. Multivariate analysis revealed that blood pressure and uric acid before onset of ST-T abnormality were chronologically changed independent of other risk factors. The time course of risk factors may be of great importance in the development of cardiovascular disorders.