QT Dispersion In Patients Research Articles

QT dispersion in patients with pulmonary embolism

Various ECG patterns have been associated with acute pulmonary embolism. However, there is no data regarding the association between QT interval measurements and pulmonary embolism. We aimed to investigate the association between QT dispersion and the severity of pulmonary embolism (PE). One hundred twenty-nine pulmonary embolism patients (mean age 58 ± 16.5 years) with ECGs obtained within the first 24 hours of hospital admission were included in the study. Patients were classified into low, intermediate and high-risk groups. We retrospectively measured ECG scores; maximum and minimum corrected QT intervals (QTc(max) and QTc(min)) and corrected QT interval dispersion (QTcd) in each risk group of patients. There was an increasing ECG score through from low to high-risk PE [3 (Interquartile Range, IQR: 2), 5 (IQR: 6) and 10 (IQR: 7) p < 0.0001]. QT interval analysis showed that QTcd was higher in high-risk group than in low and intermediate-risk groups (59.5 ± 23.4, 69.2 ± 21, 95.9 ± 33.2, p <0.001 and p = 0.01, respectively). Patients who died after diagnosis had significantly higher QTcd values at baseline compared with the QTcd values of surviving patients (89.1 ± 45.5 to 65 ± 22.9, p = 0.001). The sensitivity of QTcd > 71.5 ms for prediction of mortality was 71% with a specificity of 73% (p = 0.001). We observed a strong correlation between QTcd and ECG score values (r = 0.69, p< 0.001). There was also a correlation between QTcd values and pulmonary artery pressure (PAP) (r = 0.27, p = 0.05). QTcd is significantly increased in high-risk PE patients compared to intermediate and low-risk patients. In addition, QTcd is significantly correlated with ECG score and PAP.

The effects of early percutaneous coronary intervention on the QT dispersion in patients with acute myocardial infarction

Objective To investigate the effect of acute intervention therapy on the QT dispersions(QTd)and correction QTd(QTcd)in patients with myocardial infarction. Methods 112 patients with myocardial infarction who had received acute percutaneous coronary intervention(PCI)as study group,and divided it into three sub-group as Left anterior descending group,Left circumflex group and Right coronary group.70 infarction patients without acute intervention therapy as control group.And 12 lead standard surfaces ECG were recorded at beginning and 24h and 48h.respectively. Results After the PCI therapy,QTd and QTcd in study group improved significantly.However,QTd and QTcd had no difference among three sub-group. Conclusion The acute intervention therapy could improve QTd and QTcd in patients with myocardial infarction.The vascular location had no difference in myocardial repolarization. Key words: PCI; Acute myocardial infarction; QTd; QTcd

The relationship between angiotensin converting enzyme gene I/D polymorphism and QT dispersion in patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is characterized by disorganized myocardial architecture, and may cause ventricular arrhythmias and sudden death. The angiotensin-converting enzyme (ACE) with two deletion alleles (DD genotype) has been proposed to be associated with increased myocardial collagen content. We evaluated QT dispersion (QTd), which reflects regional differences in ventricular repolarization, in HCM patient and controls among the three different ACE genotypes. Sixty-three patients with HCM and 20 healthy subjects were included in the study. QT parameters were measured from 12 lead electrocardiograms. ACE genotypes were determined from the DNA extracted from peripheral blood by a polymerase chain reaction (PCR) method. QT parameters were compared among the three ACE genotypes both in HCM patients and controls. Median ages were similar in HCM and control groups. QTd and corrected QTd (QTcd) were significantly greater in the HCM group compared with the controls. The frequencies of each genotype were similar in both groups. Although QTd and QTcd did not differ among the three genotypes in the control subjects, they were significantly greater in patients with DD genotype compared with other genotypes in the HCM group. QTd and QTcd are increased in patients with HCM, especially in those with the DD genotype.

OP-111 RELATIONSHIP BETWEEN CIRCADIAN BLOOD PRESSURE PATTERN AND QT DYNAMICITY IN PATIENTS WITH ARTERIAL HYPERTENSION

ECG recordings (SDNN); the standart deviation of all 5-minute RR interval means in milliseconds (SDANN), root mean-square differences between consecutive RR intervals of the entire recording in milliseconds (rMSSD); the percentage of differences between adjacent filtered RR intervals that are greater than 50 ms for the whole analysis (pNN50). A standart 12-lead ECG was recorded with a paper speed of 25mm/s. The difference between the maximum and minimum QT intervals on any standart 1lead ECG was calculated as QT dispersion. Results: Basal clinical, hematologic and biochemical characteristics were similar between groups. LV diastolic function and LVEF were detected similar in both groups. The rhythm was sinus and there was no conduction abnormality in all subjects. Mean values of HRV parameters are listed. With respect to time domain indexes, SDNN, pNN50 and rMSSD values were significantly decreased in patients with BD. There was no statistical difference between the mean QT values of the patient and control groups however, QT dispersion parameters in the Behcet’s patients were longer than in controls. Conclusions: The reason for the attenuated HRV and impaired QT dispersion in patients with BD is not clear. The most probable underlying basis is believed to be vasculitis, which involves multiple systems.

Long-Term Exercise-Training Improves QT Dispersion in the Metabolic Syndrome

Increased QT dispersion (QTd) is a marker of myocardial electrical instability and predicts ventricular arrhythmias and sudden cardiac death. Exercise training (ET) has been shown to reduce both QTd and cardiovascular mortality in various populations. Patients with metabolic syndrome (MS) have been shown to have increased QTd. The effect of ET on QTd in MS patients however is unknown. We sought to assess the effect of a long-term (> or = 6 months) ET program on QTd parameters in MS patients with and without coronary heart disease (CHD). Fifteen CHD and 31 non-CHD patients with MS (mean age, 64 +/- 7 and 57 +/- 9 years, respectively) were identified at entry into identical ET programs. MS was defined using modified National Cholesterol Education Program criteria. A control group consisted of 8 MS patients with CHD (mean age, 65 +/- 6 years). Ventricular repolarization (QT dispersion = QTd, standard deviation of QT = SDQT, relative dispersion of QT = RDQT, QT corrected dispersion = QTcd), metabolic and exercise parameters were measured before and after ET. Program duration was over 9 months (312 +/- 100 versus 284 +/- 101 days in CHD and non-CHD cohorts, P = NS). QTd decreased in both ET groups (QTd pre versus post = 66 versus 56 ms in CHD group, P < 0.01; 58 versus 51 ms in non-CHD group, P < or = 0.01). Other ventricular repolarization parameters also improved significantly in both MS groups following ET, but remained unchanged in the control group. A long-term ET program improves QTd in patients with MS with and without CHD.

QTc Interval and QT Dispersion in Patients with Thalassemia Major: Electrocardiographic (EKG) and Echocardiographic Evaluation

Doppler echocardiographic studies in patients with beta-Thalassemia Major (beta-TM) had shown different patterns of left ventricle (LV) systolic and diastolic dysfunctions. This cross-sectional study was designed to study the LV systolic and diastolic function in patients with beta-TM using Pulsed Doppler (PD) Echocardiogram and assess the QTc interval and QT dispersion (QTd) on 12 leads ECG. All patients were evaluated clinically as well as by echocardiography and 12 leads ECG. The study included patients with beta-TM (n = 38, age 15.7 +/- 8.9 years), compared with an age-matched healthy control group (n = 38, age 15.9 +/- 8.9 years). In 38 patients with beta-TM Compared with healthy control group, The QTc interval and the QTd dispersion on ECG were increased with no significant difference mode echo showed that beta-TM patients have thicker LV septal wall index (0.659 +/- 0.23 vs. 0.446 +/- 0.219 cm/M(2), P < 0.001), posterior wall index (0.659 +/- 0.235 vs. 0.437 +/- 0.214 cm/M(2), P < 0.01), and larger LVEDD index is (3.99 +/- 0.48 vs. 2.170 +/- 0.57 cm/M(2). P < 0.05). Pulsed Doppler showed high LV trans-mitral E wave velocity index (70.818 +/- 10.139 vs. 57.532 +/- 10.139, P < 0.05) and E/A ratio (1.54 vs.1.23, P < 0.01). The duration of deceleration time index (DT) and isovolumic relaxation time index (IVRT) were significantly shorter in patients with beta-TM (150.234 +/- 20.0.23 vs. 167.123 +/- 167.123 +/- 19.143 msec/M(2), P < 0.01) and (60.647 +/- 6.77 vs. 75.474 +/- 5.83 msec/M(2), P < 0.001), respectively. The tricuspid valve velocity in patients with beta-TM was significantly higher than controls (2.993 +/- 0.569 vs. 1.93 +/- 0.471 m/sec, respectively, P < 0.01), with calculated pulmonary artery pressure of 2.4 times the control (36.0 vs. 14.8 mmHg). However, the LVEF% or fractional shortening were not significantly different. In this study, beta-thalassemia major patients compared with controls have differences of QT dispersion and corrected QT interval that is of no statistical significance. A significantly thicker LV wall and LV diastolic filling indices are suggestive of restrictive diastolic pattern. These data indicate that LV diastolic abnormalities compromised initially in patients with beta-thalassemia major.

Myocardial delayed-enhancement pattern in cardiac MRI relates with signal averaging ECG and QT dispersion in patients with myocardial infarction

Myocardial delayed-enhancement pattern in cardiac MRI relates with signal averaging ECG and QT dispersion in patients with myocardial infarction

Changes in autonomic regulation and ventricular repolarization induced by subclinical hyperthyroidism

The aim of the present study was to evaluate the effect of subclinical hyperthyroidism (SHT) on cardiovascular autonomic function and ventricular repolarization. Methods Thirty subjects (25 females; mean age 49.6 ± 9.8 years) with SHT, as judged by reduced TSH serum levels and normal free T4 and T3 serum levels, and 30 age and sex-matched control subjects underwent standard 12-lead ECG, and 24 h ambulatory ECG monitoring. The dispersion of the QT interval, an index of inhomogeneity of repolarization, and the heart rate variability (HRV), a measure of cardiac autonomic modulation, were studied. Results Patients with SHT showed higher QT dispersion ( p < 0.001) and lower HRV measures (0.01 > p < 0.001) than controls. In SHT patients, QT dispersion was inversely related to HRV ( r = −0.47, p < 0.01). Conclusion The results of the present study demonstrated that SHT is associated with a sympathovagal imbalance, characterized by increased sympathetic activity in the presence of diminished vagal tone, and with an increased inhomogeneity of ventricular recovery times. The assessment of HRV and QT dispersion in patients with SHT may represent a useful tool in monitoring the cardiovascular risk of this condition.

The Effect of Acute Psychological Stress on QT Dispersion in Patients with Coronary Artery Disease

An acute psychological stress can precipitate ventricular arrhythmias and sudden cardiac death in patients with coronary artery disease (CAD). However, the physiologic mechanisms by which these effects occur are not entirely clear. Mental stress-induced myocardial ischemia occurs in a significant percentage of the CAD population. It is unknown if the proarrhythmic effects of psychological stress are mediated through the development of myocardial ischemia. To examine the effects of psychological stress on QT dispersion (QTd) among CAD patients and whether these effects are mediated via the development of myocardial ischemia. Psychological stress was induced using a public speaking task. Twelve-lead electrocardiograms (ECG) were recorded at rest, during mental stress, and during recovery. QTd was calculated as the difference between the longest and the shortest QT interval in the 12-lead ECG. Rest-stress myocardial perfusion imaging was also performed to detect mental stress-induced myocardial ischemia. Mental stress induced a significant increase in QTd compared to the resting condition (P < 0.001). This effect persisted beyond the first 10 minutes of recovery (P < 0.001). QTd was significantly associated with the development of mental stress ischemia with ischemic patients having significantly higher QTd during mental stress than nonischemic patients (P = 0.006). This finding remained significant after controlling for possible confounding factors (P = 0.01). An acute psychological stress induces a significant increase in QTd, which persists for more than 10 minutes after the cessation of the stressor. This effect seems to be, at least partially, mediated by the development of mental stress-induced myocardial ischemia.

Heart rate-corrected QT interval and QT dispersion in patients with pulmonary hypertension

Heart rate-corrected QT interval (QTc) and QTc dispersion (QTcd) are increased and associated with ventricular arrhythmia and an increase in sudden death in a variety of diseases. This study aimed to examine QTc and QTcd in pulmonary hypertension and assess their relationship with pulmonary arterial pressure. A total of 201 patients who had undergone right heart catheterization for a preliminary diagnosis of pulmonary hypertension between December 2003 and July 2008 were included in the study. Resting 12-lead electrocardiogram was recorded. QT interval was measured manually and corrected using Bazett's formula. Patients were divided into groups with mild-to-moderate and severe pulmonary hypertension and a control group according to mean pulmonary arterial pressure. In all observed cases, mean QTc was higher in severe pulmonary hypertension than in controls (428.6 +/- 32.8 ms vs. 411.1 +/- 28.4 ms, P = 0.018) and QTcd was higher in mild-to-moderate (60.1 +/- 17.2 ms) and severe pulmonary hypertension (63.9 +/- 20.5 ms) than in controls (47.3 +/- 10.6 ms) (P = 0.031; P = 0.004). In men, there was no significant difference in mean QTc and QTcd. In women, mean QTc was higher in severe pulmonary hypertension than in controls (436.1 +/- 39.4 ms vs. 407.6 +/- 24.8 ms, P = 0.037) and QTcd was higher in severe pulmonary hypertension (68.5 +/- 20.9 ms) than in both the controls (45.1 +/- 12.6 ms) and patients with mild-to-moderate pulmonary hypertension (58.6 +/- 14.7 ms) (P = 0.002; P = 0.003). In addition, in women with pulmonary hypertension, mean QTc and QTcd were positively correlated to mean pulmonary arterial pressure (r = 0.207, P = 0.03; r = 0.236, P = 0.012). In women with pulmonary hypertension, mean QTc and QTcd are positively correlated to mean pulmonary arterial pressure and are significantly increased in patients with severe pulmonary hypertension.

Effect of different intra-abdominal pressure levels on QT dispersion in patients undergoing laparoscopic cholecystectomy

Hemodynamic changes caused by carbon dioxide (CO(2)) insufflation occur frequently in patients who undergo laparoscopic surgery. One indicator of these changes is corrected QT dispersion (QTcd), an index of myocardial function. Prolongation of QTcd has been associated with cardiovascular morbidity and mortality. We compared the effects of high-pressure (15 mmHg) and low-pressure (7 mmHg) CO(2) pneumoperitoneums on the QT interval, the rate-corrected QT interval (QTc), the QT dispersion (QTd), and the corrected QT dispersion (QTcd) during laparoscopic cholecystectomy. Twenty consecutive patients were in a low-pressure pneumoperitoneum group and 32 were in a high-pressure pneumoperitoneum group. A 12-lead electrocardiogram was used to monitor cardiac variables. In all patients, serial electrocardiograms were recorded before anesthesia induction (baseline), immediately after the pneumoperitoneum had been created, every 15 minutes during CO(2) insufflation, and 5 minutes after deflation. Two observers measured the QT intervals independently, and the QTcd was calculated using Bazett's formula. The QT interval and the QTc interval did not change significantly during the study in either group. The QTd and QTcd in the high-pressure pneumoperitoneum group increased significantly during CO(2) insufflation and were significantly higher in the high-pressure pneumoperitoneum group compared with the low-pressure pneumoperitoneum group. Changes caused by CO(2) insufflation were reversible. Statistically significant increases of QTd and QTcd, which are associated with an increased risk of arrhythmias and cardiac events, occur during CO(2) insufflation in both high-pressure and low-pressure pneumoperitoneums. QTd and QTcd were significantly higher in the high-pressure pneumoperitoneum group than they were in the low-pressure pneumoperitoneum group. QT interval changes were not related to anesthetic agents, surgical stress, hypercapnia, or duration of CO(2) insufflation. Increased intra-abdominal pressure may have caused these changes.

Cardiac Iodine-123 Metaiodobenzylguanidine Imaging Predicts Sudden Cardiac Death Independently of Left Ventricular Ejection Fraction in Patients With Chronic Heart Failure and Left Ventricular Systolic Dysfunction: Results From a Comparative Study With Signal-Averaged Electrocardiogram, Heart Rate Variability, and QT Dispersion

We prospectively compared the predictive value of cardiac iodine-123 metaiodobenzylguanidine (MIBG) imaging for sudden cardiac death (SCD) with that of the signal-averaged electrocardiogram (SAECG), heart rate variability (HRV), and QT dispersion in patients with chronic heart failure (CHF). Cardiac MIBG imaging predicts prognosis of CHF patients. However, the long-term predictive value of MIBG imaging for SCD in this population remains to be elucidated. At entry, cardiac MIBG imaging, SAECG, 24-h Holter monitoring, and standard 12-lead electrocardiography (ECG) were performed in 106 consecutive stable CHF outpatients with a radionuclide left ventricular ejection fraction (LVEF) <40%. The cardiac MIBG washout rate (WR) was obtained from MIBG imaging. Furthermore, the time and frequency domain HRV parameters were calculated from 24-h Holter recordings, and QT dispersion was measured from the 12-lead ECG. During a follow-up period of 65 +/- 31 months, 18 of 106 patients died suddenly. A multivariate Cox analysis revealed that WR and LVEF were significantly and independently associated with SCD, whereas the SAECG, HRV parameters, or QT dispersion were not. Patients with an abnormal WR (>27%) had a significantly higher risk of SCD (adjusted hazard ratio: 4.79, 95% confidence interval: 1.55 to 14.76). Even when confined to the patients with LVEF >35%, SCD was significantly more frequently observed in the patients with than without an abnormal WR (p = 0.02). Cardiac MIBG WR, but not SAECG, HRV, or QT dispersion, is a powerful predictor of SCD in patients with mild-to-moderate CHF, independently of LVEF.

Lack of Diurnal Variation of P‐Wave and QT Dispersions in Patients with Heart Failure

P-wave dispersion (PWD) is a new parameter for the assessment of risk of atrial fibrillation and has been reported to be increased in heart failure. Diurnal variation of the PWD has been reported in patients with coronary artery disease (CAD). QT dispersion (QTD) has also a circadian variation. In this study we aimed to search diurnal variation of PWD and QTD in patients with heart failure. Fifty-three clinical heart failure patients having left ventricular ejection fraction (LVEF) <40% were divided into two groups according to presence of CAD. Twelve-lead ECGs were obtained in the morning (07:00-08:00 hours), at noon (12:00-14:00 hours), and at night (22:00-24:00 hours). All the patients were in New York Heart Association class II except one in class I. beta-blocker and angiotensin-converting enzyme inhibitor or angiotensin receptor blocker usage was over 80% and spiranolactone usage was around 75% in the study group. PWD and QTD were not significantly different between patients with (n = 27) and without (n = 26) CAD. There was no significant diurnal variation of P wave and QT parameters. We found that PWD and QTD do not show diurnal variation in patients having either ischemic or nonischemic origin of heart failure treated with optimal drug therapy.

The Comparative Effects of Long-Term Carvedilol versus Bisoprolol Therapy on QT Dispersion in Patients with Chronic Heart Failure

Objectives: Carvedilol and bisoprolol reduce QT dispersion (QTD) in chronic heart failure (CHF). However, it is unclear whether there is a difference between the effects of the two drugs. The aim of the present study was to compare the long-term effects of carvedilol and bisoprolol on QTD in patients with CHF. Methods: Eighty-one patients with CHF with no previous β-blocker therapy were included in this prospective study. The patients were randomly allocated to carvedilol or bisoprolol therapy. Left ventricular ejection fraction (LVEF), heart rate (HR), QTD, and corrected QTD (QTcD) were calculated at baseline and at the 6th month of therapy. Results: In comparison to baseline values in both therapy groups, LVEF was significantly improved, and a statistically significant decrease was found in HR (carvedilol from 76 ± 12 to 65 ± 10 beats/min, p < 0.001; bisoprolol from 78 ± 13 to 65 ± 8 beats/min, p < 0.001) and QTcD (carvedilol from 85 ± 28 to 65 ± 22 ms, p < 0.001; bisoprolol from 83 ± 22 to 61 ± 20 ms, p < 0.001). In our study, carvedilol and bisoprolol were found to have similar effects on LVEF, HR, and QTcD. Conclusions: Carvedilol and bisoprolol decrease HR and QTcD in patients with CHF, and there is no meaningful difference between the two β-blockers as regards their effects on these parameters.

QT dispersion in patients with acute ischemic stroke who underwent thrombolytic treatment: Is it really useful to predict good neuorologic recovery?

In the current study, ΔQT dispersion (ΔQTD) was found to be a new predictor of neurologic change which may be potentially useful in prediction of functional recovery in patients with acute cerebrovascular accident treated with thrombolytic treatment. We believe that ΔQTD might be a new prognostic determiner in patients with acute cerebrovascular accident undergoing thrombolytic treatment. But it is too early to talk about the prognostic significance in patients with acute cerebrovascular accident not undergoing thrombolytic treatment.

Changes in heart rate variability and QT dispersion in patients with overt hypothyroidism

The aim of the present study was to evaluate the effect of clinical hypothyroidism on cardiovascular autonomic function and ventricular repolarization. We studied 31 patients (22 females and 9 males; mean age 53.6+/-11.8 years) with overt hypothyroidism (TSH=56.2+/-14.7 microU/ml, low free thyroxine (T4), free tri-iodothyronine (T3)) and 31 euthyroid controls, to investigate the dispersion of the QT interval in electrocardiogram (ECG) (an index of inhomogeneity of repolarization) and heart rate variability (HRV; a measure of cardiac autonomic modulation). The hypothyroid patients and controls underwent a full medical examination, standard 12-lead ECG, and 24-h ambulatory ECG monitoring. The hypothyroid patients were re-examined after 6 months of treatment with L-T4. Patients with hypothyroidism showed higher QT dispersion and lower HRV measures than controls (P<0.01 or P<0.001). In hypothyroid patients, standard deviation of all R-R intervals was inversely related (by simple regression) to serum (log)TSH levels (r=-0.47, P=0.008), while QT dispersion (r=0.50, P=0.004) and QTc dispersion (r=0.46, P=0.008) were directly related to (log)TSH. Parameters of HRV improved after 6 months of L-T4 treatment, with the correction of hypothyroidism, becoming comparable with those of the control subjects, whereas the QT and QTc dispersion results were found to be only partially restored, remaining higher than the controls. The results of the study demonstrate that hypothyroidism is associated with a decreased sympatho-vagal modulation of the heart rate and with an increased inhomogeneity of ventricular recovery times. The assessment of HRV and QT dispersion in patients with overt hypothyroidism may represent a useful tool in monitoring the cardiovascular risks.

The effects of hemodialysis on QT dispersion in patients with chronic renal failure

The effects of hemodialysis on QT dispersion in patients with chronic renal failure

Diurnal variation in QT dispersion in patients with low hemoglobin level

Diurnal variation in QT dispersion in patients with low hemoglobin level

Changes in QT dispersion after thrombolysis for stroke

Background QT dispersion (QTD) reflects heterogeneity of myocardial repolarization, which is modulated by the central nervous system. Although largely studied in patients with cardiovascular disease, QTD is increased in acute stroke and this finding is an independent predictor of functional outcome and mortality following acute neurological events. Hypothesis The hypothesis of this study was to determine whether changes in QTD in patients presenting with ischemic stroke parallel changes in neurologic function. Methods We retrospectively studied 30 consecutive patients (76 ± 9 years, 50% male) who received thrombolytic therapy for acute ischemic stroke between September 1996 and August 2002, and had multiple electrocardiograms (ECGs). QTD was calculated from the admission ECG and the last available ECG (median 3 days) during hospital admission as the absolute difference between the maximum and minimum QT intervals in at least 11 of 12 leads. The National Institute of Health Stroke Scale (NIHSS) was used to assess neurological status on admission and discharge. ΔQTD was calculated as the absolute difference between QTD measured on admission and on the last available ECG. Absolute changes in heart rate corrected QTD (ΔQTDc) and NIHSS scores (ΔNIHSS) were also calculated. Results ΔQTD was significantly higher in the 27% of patients who died as compared to the survivors (44 ± 26 ms vs. − 2 ± 21 ms, p < .001). ΔNIHSS correlated directly with ΔQTD ( r = 0.57, p < 0.001) and with ΔQTDc ( r = 0.60, p < 0.001). The NIHSS score changed in the same direction 3.1 units (95% CI: 2.0, 4.2) for every 10 ms change in QTD. Conclusion ΔQTD are associated with changes in neurological function in patients treated with thrombolytic therapy for acute ischemic stroke.

Increased QT Dispersion in Sickle Cell Disease: Effect of Pulmonary Hypertension

Background: QT dispersion has been proposed to be a predictor of adverse outcomes in a variety of cardiac disease states. The objective of this study was to examine QT dispersion in patients with sickle cell disease (SCD) and to assess the effect of pulmonary hypertension (PHT) on QT dispersion. Methods: We performed Doppler echocardiographic assessments of pulmonary artery systolic pressure in 73 (mean age 18.5 ± 8.0 years) steady-state SCD patients and 25 (mean age 19.6 ± 7.2 years) healthy subjects. Resting 12-lead electrocardiogram was recorded and QT dispersion was calculated as the difference between maximum and minimum QT intervals. Bazett’s formula was used to obtain a rate-corrected value of the QT interval (QTc). Results: Maximum QTc, minimum QTc and QTc dispersion were significantly increased in SCD patients compared to the control subjects (p < 0.0001, p < 0.05, p < 0.0001, respectively). Among SCD patients, patients with PHT had higher maximum QTc and QTc dispersion than patients without PHT (p < 0.0001). However, minimum QTc showed no significant differences between the two patient groups. Conclusion: QTc dispersion is significantly increased in SCD patients, especially those with PHT indicating regional inhomogeneity of ventricular repolarization.