Repolarization abnormalities in patients with idiopathic ventricular tachycardias

STUDY POPULATION: Twenty patients without laboratory evidence of cardiac di sease who underwent electrophysiological study because of recurrent ventric ular tachyarrhythmias. PATIENTS AND METHODS: The study population was divided into two groups: gro up A (20 patients [six males and 14 females] mean age 42.2 +/- 13 years), w ith idiopathic ventricular tachycardia (VT), and group B (30 controls [10 m ales and 20 females] mean age 43.6 +/- 16 years). Noninvasive multiparametr ic analysis of the ventricular repolarization phase was performed on the st andard 12-lead electrocardiogram by using a digitizer connected with a comp uterized system. The intervals JT, heart rate-corrected JT (JTc), JT apex ( JTa), heart rate-corrected JTa (JTac), T apex T end (TaTe) and heart rate-c orrected TaTe (TaTec) were measured and considered to be representative of the whole depolarization process. QT dispersions (QTeD) and QTc dispersions (QTecD) were calculated to assess the degree of spatial inhomogeneity of a ction potential duration. RESULTS: Patients in group A had higher JT (272 +/- 36 ms versus 265 +/- 25 ms, P = 0.01), JTc (336 +/- 28 ms versus 318 +/- 18 ms, P = 0.01), JTa (21 0 +/- 28 ms versus 185 +/- 28 ms, P = 0.001) and JTac (240 +/- 20 ms versus 215 +/- 13 ms, P < 0.001) values than those of patients in group B, despit e shorter TaTe (71 +/- 10 ms versus 90 +/- 18 ms, P < 0.001) and TaTec (88 +/- 12 ms versus 110 +/- 12 ms, P < 0.001). Moreover, QTeD and QTecD were s ignificantly longer in group A than in group B (55 +/- 18 ms versus 42 +/- 19 ms [P = 0.01] and 80 +/- 18 ms versus 55 +/- 28 ms [P = 0.001], respecti vely). CONCLUSIONS: Patients with idiopathic VT exhibit inhomogeneous prolongation of ventricular repolarization, due to a considerable increase in the initi al part in association with a shorter terminal phase, as well as a greater dispersion of ventricular repolarization.