The prolongation of intraatrial and interatrial conduction time and the inhomogeneous propagation of sinus impulses have been shown in patients with atrial fibrillation. Recently P wave dispersion (PWD), which is believed to reflect inhomogeneous atrial conduction, has been proposed as being useful for the prediction of paroxysmal atrial fibrillation (PAF). Ninety consecutive patients (46 men, 44 women; aged 55 +/- 13 years) with a history of idiopathic PAF and 70 healthy subjects (42 men, 28 women; mean age 53 +/- 14 years) were studied. The P wave duration was calculated in all 12 leads of the surface ECG. The difference between the maximum and minimum P wave duration was calculated and this difference was defined as P wave dispersion (PWD = Pmax-Pmin). All patients and controls were also evaluated by echocardiography to measure the left atrial diameter and left ventricular ejection fraction (LVEF). There was no difference between patients and controls in gender (P = 0.26), age (P = 0.12), LVEF (66 +/- 4% vs 67 +/- 5%, P = 0.8) and left atrial diameter (36 +/- 4 mm vs 34 +/- 6 mm, P = 0.13). P maximum duration was found to be significantly higher in patients with a history of PAF (116 +/- 17 ms) than controls (101 +/- 11 ms, P < 0.001). P wave dispersion was also significantly higher in patients than in controls (44 +/- 15 ms vs 27 +/- 10 ms, P < 0.001). There was a weak correlation between age and P wave dispersion (r = 0.27, P < 0.001). A P maximum value of 106 ms separated patients with PAF from control subjects with a sensitivity of 83%, a specificity of 72%, and a positive predictive accuracy of 79%. A P wave dispersion value of 36 ms separated patients from control subjects with a sensitivity of 77%, a specificity of 82%, and a positive predictive accuracy of 85%. In conclusion, P maximum duration and P wave dispersion calculated on a standard surface ECG are simple ECG markers that could be used to identify the patients with idiopathic paroxysmal atrial fibrillation.

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Increased serum cTnT level can be detected in the early stages of anthracycline therapy and it is associated with diastolic dysfunction of the left ventricle. Therefore, serum cTnT level could be a useful measure for early detection of anthracycline-induced cardiotoxicity.

The present study has been designed to determine melatonin levels in type 2 diabetic patients and test the relationship between the autonomic nervous system and melatonin dynamics. Thirty-six type 2 diabetic patients and 13 age-matched healthy subjects were recruited for the study. Circadian rhythm of melatonin secretion was assessed by measuring serum melatonin concentrations between 02:00-04:00 and 16:00-18:00 hr. Melatonin dynamics were re-evaluated with respect to autonomic nervous system in diabetic patients with autonomic neuropathy who were diagnosed by the cardiovascular reflex tests, heart rate variability (HRV), and 24-hr blood pressure monitoring. Nocturnal melatonin levels and the nocturnal melatonin surge were low in the diabetic group (P = 0.027 and 0.008 respectively). Patients with autonomic neuropathy revealed decreased melatonin levels both at night and during day when compared with healthy controls (P < 0.001 and 0.004 respectively) while the melatonin dynamics were similar to controls in patients without autonomic neuropathy. Nocturnal melatonin level was positively correlated with nocturnal high and low frequency components of HRV (P = 0.005 and 0.011 respectively) and systolic and diastolic blood pressures at night (P = 0.002 and 0.004 respectively) in patients with autonomic neuropathy. We found a negative correlation between nocturnal melatonin levels and the degree of systolic blood pressure decrease at night (r = -0.478, P = 0.045). As a conclusion this study has shown that circadian rhythm of melatonin secretion is blunted in type 2 diabetic patients and there is a complex relationship between various components of autonomic nervous system and melatonin secretion at night. Among the patients with autonomic neuropathy those with more preserved HRV and the systolic nondippers (<10% reduction in blood pressure during the night relative to daytime values) have more pronounced melatonin surge at night.

Aortic insufficiency, myocardial fibrosis and conduction disturbances are known complications of ankylosing spondylitis (AS). However, few studies have assessed left ventricular diastolic function and no data are available about P-wave analysis. In this study 88 AS patients and 31 healthy volunteers underwent clinical examination, electrocardiography, echocardiography and signal-averaged P-wave analysis for the evaluation of asymptomatic cardiac involvement. The aortic root in AS patients was larger and this was correlated with the duration of the disease. Five of 88 AS patients (5.7%) had evidence of mitral valve prolapse, six (6.8%) had thick and redundant mitral valves without prolapse, five (5.7%) had mild mitral regurgitation, two had moderate (2.3%) and two had mild (2.3%) aortic regurgitation. Examination of diastolic function revealed a lower peak of E-wave velocity (E) and E/A ratio, a higher peak of A-wave velocity (A) and acceleration rate of the A wave, a longer deceleration time of E-wave velocity and isovolumic relaxation time in the AS group compared to controls. Mean filtered P-wave duration (PWD) in AS was similar to that of controls. However, PWD in AS patients was positively correlated with left atrial dimension and acceleration rate of the A wave and negatively correlated with E and E/A ratio. In conclusion, cardiac involvement may be seen in AS patients in the absence of clinical manifestations. Echocardiographic examination of diastolic function can be used in this asymptomatic period. Further studies are needed to clarify the prognostic significance of diastolic abnormalities and the value of P-wave analysis in cardiac evaluation of these patients.