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HRR and HRV are significantly reduced in CAD. The reduction in HRR is parallel to the changes in HRV parameters. HRR, which can be measured easily in the recovery phase of exercise testing, can be used to detect the depression of parasympathetic tonus and to evaluate the basal autonomic balance in this patient group.

This study shows an increase in intra-left atrial mechanical delay in PAF patients. This method can be used as an early marker to detect PAF.

Hemodialysis ends with significant increase in P wave maximum duration and P wave dispersion, which might be responsible for the increased occurrence of atrial fibrillation in these groups of patients.

SummaryBackground: Paroxysmal atrial fibrillation (PAF) in hypertrophic cardiomyopathy (HCM) is associated with poor prognosis. Previous studies have shown good correlation between P-wave dispersion (Pd) and occurrence of PAF. However, Pd in patients with HCM for predicting PAF has not been studied.Hypothesis: The aim of the study was to determine whether Pd could identify patients with HCM who are likely to suffer from PAF.Methods: Twenty-two patients with HCM with a history of PAF (Group 1) and 26 patients with HCM without a history of PAF (Group 2) were studied. Maximum (Pmax) and minimum (Pmin) P-wave durations, as well as P-wave dispersion (Pd = Pmax ϪPmin) were calculated from 12-lead surface electrocardiograms (ECG).Results: P-wave dispersion was significantly different between the groups (Group 1: 55 ± 6 ms vs. Group 2: 37 ± 8 ms; p < 0.001), while Pmax (Group 1: 134 ± 11 ms vs. Group 2: 128 ± 13 ms; p = 0.06) and Pmin (Group 1: 78 ± 9 ms vs. Group 2: 81 ± 7 ms; p = 0.07) was not significantly different. Patients with a history of PAF had higher left atrial diameter than the patients without PAF (Group 1: 52 ± 8 mm vs. Group 2: 48 ± 10 mm; p = 0.02). A cut-off value of 46 ms for Pd had a sensitivity of 76% and a specificity of 82% in discriminating between patients with and without PAF.Conclusion: This study suggests that P-wave dispersion could identify patients with HCM who are likely to develop PAF.