QT dispersion in acute rheumatic fever

Ventricular repolarization markers for predicting malignant arrhythmias in clinical practice

Malignant cardiac arrhythmias which result in sudden cardiac death may be present in individuals apparently healthy or be associated with other medical conditions. The way to predict their appearance represents a challenge for the medical community due to the tragic outcomes in most cases. In the last two decades some ventricular repolarization (VR) markers have been found to be useful to predict malignant cardiac arrhythmias in several clinical conditions. The corrected QT, QT dispersion, Tpeak-Tend, Tpeak-Tend dispersion and Tp-e/QT have been studied and implemented in clinical practice for this purpose. These markers are obtained from 12 lead surface electrocardiogram. In this review we discuss how these markers have demonstrated to be effective to predict malignant arrhythmias in medical conditions such as long and short QT syndromes, Brugada syndrome, early repolarization syndrome, acute myocardial ischemia, heart failure, hypertension, diabetes mellitus, obesity and highly trained athletes. Also the main pathophysiological mechanisms that explain the arrhythmogenic predisposition in these diseases and the basis for the VR markers are discussed. However, the same results have not been found in all conditions. Further studies are needed to reach a global consensus in order to incorporate these VR parameters in risk stratification of these patients.

QT and P-wave dispersions in rheumatic heart disease: prospective long-term follow up

BACKGROUND

Simple electrocardiogram (ECG) markers have been used to evaluate conduction times. Acute rheumatic fever (ARF) is an autoimmune disease that affects these conduction times. The aim of this prospective long-term follow-up study was to evaluate QT, QTc and P-wave dispersions in children with ARF and chronic rheumatic heart disease (CRHD).

METHODS

Sixty-four patients with ARF, 33 patients with CRHD and 41 healthy, age- and sex-matched control subjects were included in the study. The ARF patients were divided into two subgroups: carditis and arthritis. Echocardiographic and ECG measurements at the onset of diagnosis and final evaluation were included.

RESULTS

QT, QTc and P-wave dispersions were significantly greater in both the ARF carditis and CRHD groups than the ARF arthritis and control subjects during the initial and final analysis (for all, P < 0.001). There was no significant statistical difference in QT, QTc and P-wave dispersion between the initial and final analysis in each groups. Severity of mitral regurgitation and left atrial enlargement were found to be positively correlated with P-wave dispersion (r = 0.438, P < 0.001; r = 0.127, P < 0.001, respectively). QT, QTc and P-wave dispersion greater than 52, 60 and 57 ms, respectively, had higher sensitivity and specificity for predicting ARF carditis.

CONCLUSION

These ECG measurements can be used in the diagnosis of ARF carditis as minor criteria with modified Jones criteria. In contrast, this increase in the dispersions is permanent in patients with ARF carditis.

Dispersion durations of P-wave and QT interval in children with congenital heart disease and pulmonary arterial hypertension

This study aimed to investigate homogeneity disorders of ventricular repolarization and atrial conduction via QT dispersion and P-wave dispersion in children with congenital heart disease (CHD) and pulmonary arterial hypertension (PAH). Three groups of 20 each were generated and involved in this study. The first group included 20 children with both CHD and PAH. The second group consisted of 20 children with CHD but no PAH, and the third group was composed of 20 age- and sex-matched healthy children. Electrocardiographic records were used to determine P-wave, QT, and corrected QT (QTc) dispersions. The pulmonary hypertension group compared with the group having no pulmonary hypertension and the control group showed a significantly longer P-wave dispersion duration (39.10 ± 9.54 vs. 26.30 ± 4.99 ms, p < 0.001; and 24.80 ± 6.94 ms, p < 0.001, respectively) and QT dispersion duration (52.80 ± 15.11 vs. 37.60 ± 6.00 ms, p < 0.001; and 35.00 ± 7.77 ms, p < 0.001, respectively). In addition, the durations of maximum QTc and QTc dispersion were significantly longer in pulmonary hypertension group than in the other two groups. The risk of atrial and ventricular arrhythmia was found to be increased in the patients with both CHD and PAH. Physicians should pay close attention to possible atrial and ventricular arrhythmias during the treatment and follow-up evaluation of these patients.

Asymptomatic rhythm and conduction abnormalities in children with acute rheumatic fever: 24-hour electrocardiography study

Some rhythm and conduction abnormalities can occur in children with acute rheumatic fever. These abnormalities have been defined based on standard electrocardiography; however, the real prevalence of these abnormalities has not been investigated previously by the evaluation of long-term electrocardiographic recordings. In this study, we evaluated the asymptomatic rhythm and conduction abnormalities in children with acute rheumatic fever by evaluating the 24-hour electrocardiography. We evaluated the standard electrocardiography and the 24-hour electrocardiography of 64 children with acute rheumatic fever. On standard electrocardiography, the frequency of the first-degree atrioventricular block was found to be 21.9%. Electrocardiography at 24 hours detected three additional and separate patients with a long PR interval. Mobitz type I block and atypical Wenckebach periodicity were determined in one patient (1.56%) on 24-hour electrocardiography. While accelerated junctional rhythm was detected in three patients on standard electrocardiography, it was present in nine patients according to 24-hour electrocardiography. Premature contractions were present in 1.7% of standard electrocardiography, but in 29.7% of 24-hour electrocardiography. Absence of carditis was found to be related to the presence of accelerated junctional rhythm (p > 0.05), and the presence of carditis was found to be related to the presence of premature contractions (p = 0.000). In conclusion, our results suggest that in children with acute rheumatic fever, the prevalence of rhythm and conduction abnormalities may be much higher than determined on standard electrocardiography. Further studies are needed to clarify whether or not these abnormalities are specific to acute rheumatic fever.

QT Dispersion predicting acute rheumatic carditis

OBJECTIVE

To investigate QT dispersion in the surface electrocardiogram of children with rheumatic carditis.

METHODS

QT dispersion was quantitatively evaluated in 33 children with acute rheumatic carditis. As a control group, we studied 33 healthy children free of any disease. The children were eligible for participation if the following criteria were met: diagnosis of acute rheumatic fever based on the revised Jone's criteria and suffering from their first attack of carditis. The echo Doppler cardiogram was performed in all children, within 48-72 hours of hospitalisation.

RESULTS

Patients with carditis had a greater QT dispersion than the control group. When we analyse the QT dispersion according to the severity of the carditis, we observed that the dispersion tended to be greater in those with more severe valvar lesion. The sensitivity and specificity of the measurements of the QT dispersion in predicting acute carditis were estimated by using receiver operating characteristic curves. A QT dispersion greater than 40 milliseconds had a sensitivity of 63.6% and a specificity of 93.9% in predicting acute rheumatic carditis.

CONCLUSION

The lengthening of QT dispersion may reflect on cardiac involvement in rheumatic fever and be a new important parameter in the diagnosis and therapeutic decision for rheumatic carditis.