Relation of early changes of QT dispersion to changes in left ventricular systolic and diastolic function after a first acute myocardial infarction.

OBJECTIVE

To describe the relation between changes of left ventricular systolic and diastolic function and changes of QT dispersion (difference in duration between longest and shortest QT interval) following acute myocardial infarction.

DESIGN

QT dispersion was determined at admission, hospital discharge, and 1 and 3 months following myocardial infarction in 64 consecutive 1-year survivors. Patients were divided into Group A where QT dispersion was < 52 ms at all recordings or initially > 52 ms but decreased during follow-up, and Group B where QT dispersion remained increased > or = 52 ms at all measurements. Doppler-Echocardiography was carried out on day 1, day 5, and after 1, 3, and 12 months.

RESULTS

In 26 patients QT dispersion remained increased > or = 52 ms during the first 3 months after infarction. Among these a significant increase of end-systolic volume was seen whereas low or rapid normalized QT dispersion was associated with a significant decrease of ventricular volumes. After 1 year end-systolic (70 +/- 32 ml vs 49 +/- 16 ml, p = 0.006) and end-diastolic volumes (138 +/- 41 ml vs 105 +/- 22 ml, p = 0.001) were higher in Group B. In a multivariate model Group B was significantly related to an increase of end-diastolic volume (p = 0.01). In Group A diastolic function improved in eight patients and in two it deteriorated, whereas improvement was seen in one patient and deterioration in nine patients from Group B (p < 0.01).

CONCLUSION

Following myocardial infarction low QT dispersion is associated with preserved left ventricular function, whereas persistently increased dispersion is associated with left ventricular dilation and deterioration of diastolic function.