ALTERATION OF THE QT RR RELATIONSHIP IN PATIENTS WITH IDIOPATHIC VENTRICULAR-TACHYCARDIA/

It has been shown that alterations in QT/RR relationship may be associ ated with arrhythmogenesis in several clinical settings. In the presen t study the QT/RR relationship was studied in 20 patients with idiopat hic ventricular tachycardia (12 men and 8 women, aged 41 +/- 14 years) compared to 20 normal subjects (9 men and 11 women, aged 39 +/- 13 ye ars). All the patients were off any antiarrhythmic drugs and had no ev idence of intraventricular conduction defects. The QT intervals and th eir preceding RR intervals were measured on electrocardiogram strips f rom 24-hour Holter tapes at hourly intervals. The differences in the m axim um, minim um, and mean of either the QT interval or its corrected values between patients with idiopathic ventricular tachycardia and n ormal subjects were not statistically significant. There was a signifi cant correlation between the QT and RR intervals in normal subjects (g amma = 0.73 +/- 0.12, P < 0.05) and in patients with idiopathic ventri cular tachycardia (gamma = 0.80 +/- 0.10, P < 0.05). However, the line ar regression line of the QT interval against the RR interval were sig nificantly (P < 0.001) altered in patients with idiopathic ventricular tachycardia (QT = 0.24 + 0.18 RR) compared to normal: subjects (QT = 0.27 +/- 0.12 RR). We conclude that although there is no significant c hange in the QT interval and its corrected values, the QT/RR relations hip is significantly altered in patients with idiopathic ventricular t achycardia as compared to normal subjects. This may be of importance i n the pathogenesis of idiopathic ventricular tachycardia in these pati ents.