[Variations in QT interval and ventricular volume during exercise-induced myocardial ischemia]

Aim of this study was to evaluate the possible relationship among myocardial ischemia, left ventricular volume changes and QT interval changes during exercise in patients with coronary artery disease. QT interval, expressed as absolute value, corrected according to Bazett (QTc = aT/RR0.5) and Fridericia (QTf = QT/RR0.33) and calculated by adapting reciprocal changes in QT and heart rate during exercise to the exponential fit proposed by Sarma (QTs = A-B*exp (-K*RR], was compared to the scintigraphic finding of myocardial ischemia and to the changes in left ventricular volumes during exercise. We studied 151 patients (130 men and 21 women, mean age 56 +/- 11 years) with suspected or already ascertained coronary artery disease, who underwent a simultaneous evaluation of regional ventricular function and myocardial perfusion by means of first pass radionuclide angiography (multielement gamma-camera) and computerized tomography, with 2 injections of 99mTc-MIBI at rest and at peak of a computerized bicycle stress test. QT and RR intervals were measured on an averaged ECG complex through a magnifying lens, and the absolute values of left ventricular volumes were computed by radionuclide angiography. According to scintigraphic findings, patients were divided into normal subjects (n = 7) and ischemic patients with (n = 63) and without (n = 81) evidence of a previous myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)