Irbesartan Reduces QT Dispersion in Hypertensive Individuals

Abstract

Abstract-Angiotensin type 1 receptor antagonists have direct effects on the autonomic nervous system and myocardium.Because of this, we hypothesized that irbesartan would reduce QT dispersion to a greater degree than amlodipine, a highly selective vasodilator. To test this, we gathered electrocardiographic (ECG) data from a multinational, multicenter, randomized, double-blind parallel group study that compared the antihypertensive efficacy of irbesartan and amlodipine in elderly subjects with mild to moderate hypertension. Subjects were treated for 6 months with either drug. Hydrochlorothiazide and atenolol were added after 12 weeks if blood pressure (BP) remained uncontrolled. ECGs were obtained before randomization and at 6 months. A total of 188 subjects (118 with baseline ECGs) were randomized. We analyzed 104 subjects who had complete ECGs at baseline and after 6 months of treatment. Key Words: irbesartan Ⅲ amlodipine Ⅲ electrocardiography Ⅲ QT dispersion Ⅲ aged Ⅲ hypertension, essential Q T dispersion is the difference between maximal and minimal QT intervals within a 12-lead surface electrocardiogram (ECG). 1 It is thought to represent the degree of repolarization inhomogeneity in the heart. 2 Abnormal values are found in heart failure and after myocardial infarction, and these are predictive of a high rate of malignant arrhythmias and of sudden death. [3][4][5][6][7] In the healthy elderly population, a raised QTc dispersion (Ͼ60 milliseconds) is associated with a 2-fold increase in sudden cardiac death. 8 A reduction in QT dispersion is observed after successful thrombolytic therapy in acute myocardial infarction and parallels a decreased risk of arrhythmic cardiac death. 9 It is also used as a marker of therapeutic efficacy in treating patients with idiopathic long QT syndrome. 10 Another index, the QTc max, which is the longest heart rate-corrected QTc interval within a 12-lead ECG, has similar prognostic value. It predicts sudden death in diabetics 11 and in patients with ischemic heart disease. 12 It is also reduced along with QT dispersion in treating heart failure with angiotensin-converting enzyme inhibitors. 13 QT dispersion is increased in left ventricular hypertrophy (LVH) 14 and in hypertension, 15 and abnormal QT dispersion may be an early indicator of end-organ damage involving the heart in hypertension. Since angiotensin II and aldosterone have been implicated in myocyte hypertrophy 16 and cellular matrix modification, 17 respectively, we hypothesized that an angiotensin II antagonist would reduce QT dispersion. The aim of the present study was to test the hypothesis that irbesartan would favorably reduce indexes of QT dispersion compared with amlodipine, a highly selective vasodilator. Methods SubjectsMales and postmenopausal females aged 65 years or older with established or newly diagnosed mild to moderate essential hypertension (diastolic blood pressure [DBP] 95 to 110 mm Hg) were recruited. Exclusion criteria included seated systolic BP (SBP) Ͼ200 mm Hg and known or suspected seconda...

Reduction of QTc Dispersion by the Angiotensin II Receptor Blocker Valsartan May Be Related to Its Anti-Oxidative Stress Effect in Patients with Essential Hypertension

“…In the present study, treatment with valsartan significantly decreased QTc dispersion. This is consistent with previous reports demonstrating that an angiotensin II receptor blocker, irbesartan, reduced QT dispersion in patients with hypertension (24,25). Stimulation of angiotensin II receptors causes LV hypertrophy (26) and modifies the cellular matrix (27).…”

The spatial QRS-T angle as a marker of ventricular repolarisation in hypertension

“…3 High QT dispersion values have been reported in patients with systemic hypertension and LVH, 1,2,4,5 which decrease after the appropriate treatment of high BP. 5,6 However, the rather weak correlation between QT dispersion and BP levels, 5,6 or LVH 1,2,5 and the poor reproduci- bility of QT dispersion measurements, 3,7 may reduce its power to assess arrhythmia risk prospectively. 4 In this study, to estimate the dispersion of repolarisation duration, apart from QT maximum and QT dispersion, JT maximum and JT dispersion were used as more accurate measures of the ventricular repolarisation time and maximum T peak-T end and T peak-T end dispersion were used as indices of the transmural dispersion of repolarisation.…”

“…1,2,4,5 Several studies have postulated that QT dispersion values decrease when adequate blood pressure (BP) control is achieved. 5,6 However, wellknown difficulties in defining the end of the T wave, the inability to measure the QT interval in all leads, and the possible presence of U waves may contribute to poor reproducibility of QT dispersion and, vector (spatial T amplitude), the angle between the maximum spatial QRS and T vectors (spatial QRS-T angle) and the frontal plane QRS-T angle were calculated. The spatial QRS-T angle was higher in patients with high compared to those with low BP (P ‫؍‬ 0.025).…”

The Prognostic Role of ECG in Arterial Hypertension

“…However only few studies have investigated the prognostic role of QT-dispersion and QT-interval in arterial hypertension (Galinier 1997, Dimopoulos 2009, Oikarinen 2004, Saaden & Jones 2001. Antihypertensive therapy with angiotensin-converting enzyme inhibitors, calcium antagonists and beta-blockers has been shown beneficial in terms of QT-dispersion normalization and/or LVH decrease (Tomiyama 1998, Karpanou 1998, Galetta 2005,Lim 1999. Beta blockers are associated with a reduction in both QT and QTc interval dispersion, raising the possibility that a reduction in dispersion of ventricular repolarization may be an important antiarrhythmic mechanism of beta blockade.…”