QT Dispersion Ratio in Patients with Unstable Angina Pectoris (A New Risk Factor?) V.G. CIN, M.D.,M. CEI.JK,M.D., S. ULUCAN,M.D. Selquk University, School of Medicine, Cardiac Department, Konya, Turkey Summary Background: QT dispersion has been shown to be associated with fatal arrhythmias and sudden death in coronary artery disease. A recent study indicated that marked QT dispersion in electrocardiograms (ECGs) obtained during acute ischemia demonstrated a significant correlation with ventricular tibrillation. Hypothesis: This study investigated the ECG parameters for repolarization (QT dispersion, corrected QT, corrected QT dispersion, and QT dispersion ratio) and their interrelation with acute ischemia. Merh0d.s: QT parameters as well as a newly developed repolarization index, QT dispersion ratio [(QT dispersion/RR interva1)X 1001 were calculated digitally during rest and ischemia in 32 patients with coronary artery disease (rest angina, Braunwald class III). Results were correlated with clinical consequences, mainly arrhythmias, within a follow-up period of 5 k 2 days. RPSM~LSS: While most patients had an increase in all four parameters, only the QT dispersion ratio showed a significant difference when correlated with ventricular arrhythmias (p < 0.001, Fratio=38). Conclusion: QT dispersion ratio appears to be a new and promising parameter in predicting ventricular arrhythmias in patients with acute ischemia. Key words: QT dispersion, unstable angina, acute ischemia Address for reprints: V.G. Cin. M.D. Selquk Universitesi Tip fakiiltesi Kardiyoloji A.B.D. 42080 Konya, Turkey Received: December 19, 19% Accepted with revision: March 3, 1997 Introduction Repolarization abnormalities have been shown to play an active role in leading to secondary arrhythmias in patients with coronary artery disease. Id A recent study indicated that marked QT dispersion in electrocardiograms (ECGs) obtained during acute ischemia demonstrated a signi ficant correlation with ventricular fibrillation.6 In this study a similar interrelation and its possible effect on prognosis in patients with unstable angina pectori was investigated. Method Standard 12-lead surface ECGs were obtained during acute anginal episodes and uneventful periods in 32 patients (21 women, 9 men; mean age 64 k 10 years) with coronary ruteiy disease (Braunwald class 111 rest angina). The diagnosis of coronary artery disease was confirmed by observation of at least 1 mm of reversible horizontal ST depression on any two surface ECG leads with simultaneous typical rest angina. RR interval, maximum QT duration (from onset of QRS complex to the end of the T wave), en az QT duration, QT dispersion (QT max-QT min), QTc (QTRR; QT duration in ms divided by the square root of RR interval: Bazzet’s formula), QTc dispersion (QTc max-QTc min), and QT dispersion ratio [(QTd/RR)X 1001 were calculated in each patient. All calculations were made by computer, using the Quinton 5000 digitalized system, entering manually measured QT intervals. Patients were followed up for a period of 5 rt 2 days with respect to rhythm and conduction disturbances. Continuous ECG monitoring and 24-h Holter recordings were obtained as well. All measurements were made with the patients free ofmedication, except for nitrates (either intravenous or p.0.) and heparin (20000 U/24 h), to avoid interference from adverse electrophysiologic effects. Statistics All figures are expressed as mean k standard deviation. Student’s t-test was used to explain the statistical difference of continuous variables of ECG in Table I. chi-square testing was 534 Clin. Cardiol. Vol. 20, June 1997 TABLE I iQT parameters in ventricular anhythmias (n = 8) iQTd ratio iQTcd iQTd iQTC Angina 8 3 4 3 Rest 0 5 4 5 p Value p>
Okumaya devam et...
Okumaya devam et...