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Background: Imbalance in autonomic nervous system and impaired myocardial repolarization has been shown to increase the risk for arrhythmias in patients with coronary artery disease. This study evaluated the effects of coronary artery bypass grafting (CABG) on heart rate variability and QT interval dynamicity in subjects with coronary artery disease undergoing elective CABG surgery., Methods: The study group consisted of 68 consecutive patients (mean age +/-SD: 61 +/- 9 years) with coronary artery disease who underwent elective CABG. Twenty-four-hour Holter monitoring was performed 2-5 days before cardiac surgery and was repeated 10 days after CABG. ELATEC holter software was used to calculate heart rate variability and QT dynamicity parameters. All subjects had a complete history, laboratory examination and transthoracic echocardiography., Results: All patients had beta-blocking agent medication pre- and postoperatively. Standard deviation of all NN intervals for a selected time period, square root of the mean of the sum of the squares of differences between adjacent RR intervals, the proportion of differences in successive NN intervals greater than 50 ms, normalized low-frequency power, and normalized high-frequency power were significantly decreased after CABG surgery, whereas low-frequency/high-frequency ratio was significantly increased after CABG. QT/RR slopes over 24 h were significantly increased after CABG surgery for QT end and QT apex (QTapex/RR: 0.16 +/- 0.13 vs. 0.28 +/- 0.19, p < 0.001; QTend/RR: 0.18 +/- 0.13 vs. 0.36 +/- 0.23, p < 0.001)., Conclusion: This prospective study showed for the first time that CABG was associated with a significant worsening of heart rate variability and QT dynamicity parameters in the postoperative period., (Copyright 2006 S. Karger AG, Basel)

Background: Onset of atrial fibrillation in hypertensive patients is usually associated with a high occurrence of cardiovascular complications. Therefore, it is important to assess non-invasively the risk of developing paroxysmal atrial fibrillation (PAF) in hypertensive patients during sinus rhythm. This study was undertaken to determine if hypertensive patients with history of PAF could be identified while in sinus rhythm by measurement of signal-averaged ECG P-wave duration., Methods: Signal-averaged electrocardiography (SAECG) P-wave recording was performed in 44 hypertensive patients (30 men and 14 women; mean age 60+/-11 years, group A) who had a history of paroxysmal AF and in 50 hypertensive patients without history of AF (33 men and 17 women; mean age 57+/-12, group B). All patients were also evaluated by using echocardiography to measure left ventricular ejection fraction (LVEF) and left atrial diameter (LAD)., Results: SAECG P-wave duration was found to be significantly higher in group A than in group B (146+/-14 ms vs. 128+/-11 ms, p<0.001). Left atrial diameter was not significantly different (40.1+/-3.4 mm vs. 39.3+/-3.0 mm, p>0.05), whereas LVEF was significantly lower in group A than group B (63+/-5% vs. 67+/-4%, p=0.03). There was a correlation between SAECG P-wave duration and age (r=0.32, p<0.05). In univariate analysis, SAECG P-wave duration and LVEF were significant predictors of PAF, but only SAECG P-wave duration remained a significant independent predictor of PAF in multivariate analysis., Conclusion: The results of this study indicate that hypertensive patients with history of PAF can be detected while in sinus rhythm by signal-averaged ECG P-wave duration.

Aims The P-wave duration (PWD) has been shown to prolong in conditions associated with elevated left ventricular end-diastolic and left atrial pressures, which also increase during transient coronary artery occlusions such as angioplasty. The aim of this study was to investigate the effects of angioplasty-induced myocardial ischaemia on signal averaged PWD in patients undergoing coronary angioplasty. Methods Eighty-four consecutive adult patients with single-vessel coronary artery disease undergoing elective coronary angioplasty were included. Duration of the P wave before and during coronary angioplasty were evaluated using signal averaged P-wave analysis. Patients were classified in groups according to the artery occluded, as left anterior descending (LAD) Group, right coronary artery (RCA) Group or Others Group (which included obtuse marginal, circumflex or diagonal). Results Patients included in the LAD, RCA and Others groups were similar with respect to clinical characteristics. The mean PWD at baseline was similar in all lesions (P>0.05), whereas mean PWD at inflation was significantly longer in LAD Group compared with RCA (126.1 +/- 9.5 ms vs 118.7 +/- 10.4 ms, P=0.007) and Others (126.1 +/- 9.5 ms vs 116.3 +/- 8.6 ms, P<0.001). The PWD during balloon inflation was significantly prolonged in all groups compared with baseline levels (LAD Group 126.1 +/- 9.6 ms vs 109.7 +/- 8.0 ms; RCA Group 118.7 +/- 10.4 ms vs 108.3 +/- 8.4 ms and Others Group 116.3 +/- 8.6 ms vs 109.7 +/- 6.0 ms, all P values <0.001). Conclusion Signal-averaged PWD significantly increases during single-vessel coronary angioplasty. This increase is more pronounced for LAD lesions. However, the clinical implications of P-wave prolongation during balloon angioplasty and the value of PWD as a measure of ischaemia remains to be clarified.