Elias Gialafos

Simple electrocardiographic markers for the prediction of paroxysmal idiopathic atrial fibrillation

BACKGROUND The prolongation of intraatrial and interatrial conduction time and the inhomogeneous propagation of sinus impulses are well known electrophysiologic characteristics in patients with paroxysmal atrial fibrillation (PAF). METHODS To search for possible electrocardiographic markers that could serve as predictors of idiopathic PAF, we measured the maximum P-wave duration (P maximum) and the difference between the maximum and the minimum P-wave duration (P dispersion) from the 12-lead surface electrocardiogram of 60 patients with a history of idiopathic PAF and 40 age-matched healthy control subjects. RESULTS P maximum and P dispersion were found to be significantly higher in patients with idiopathic PAF than in control subjects. A P maximum value of 110 msec and a P dispersion value of 40 msec separated patients from control subjects, with a sensitivity of 88% and 83% and a specificity of 75% and 85%, respectively. CONCLUSIONS P maximum and P dispersion are simple electrocardiographic markers that could be used for the prediction of idiopathic PAF.

Effects of Ischemia on P Wave Dispersion and Maximum P Wave Duration During Spontaneous Anginal Episodes

P wave dispersion (P dispersion), defined as the difference between the maximum and the minimum P wave duration, and maximum P wave duration (P maximum) are electrocardiographic (ECG) markers that have been used to evaluate the discontinuous propagation of sinus impulses and the prolongation of atrial conduction time, respectively. To study the effects of myocardial ischemia on P dispersion and P maximum, 95 patients with coronary artery disease (CAD) and typical angina pectoris and 15 controls with anginalike symptoms underwent 12‐lead surface ECG during and after the relief of pain. During pain and during the asymptomatic period, P maximum and P dispersion were calculated from the averaged complexes of all 12 leads. P dispersion increased significantly during spontaneous angina (45 ± 17 ms) compared to the asymptomatic period (40 ± 15 ms), P < 0.001 only in the patient group. Both P maximum and P dispersion showed higher values during angina in those patients who developed diffuse ischemia, as estimated with ST segment changes in multiple ECG leads. P dispersion showed higher values during the anginal episode in patients with left ventricular dysfunction, independently of the presence of a previous myocardial infarction. Atrial conduction abnormalities, as estimated with P maximum and particularly P dispersion, are significantly influenced by myocardial ischemia in patients with CAD and spontaneous angina.

CLimate Impacts on Myocardial infarction deaths in the Athens TErritory: the CLIMATE study

Objective: To evaluate the impact of meteorological variables on daily and monthly deaths caused by acute myocardial infarction (AMI). Methods: All death certificate data from the Athens territory were analysed for AMI deaths in 2001. Daily atmospheric temperature, pressure and relative humidity data were obtained from the National Meteorological Society for Athens for the same year. Results: The total annual number of deaths caused by AMI was 3126 (1953 men) from a population of 2 664 776 (0.117%). Seasonal variation in deaths was significant, with the average daily AMI deaths in winter being 31.8% higher than in summer (9.89 v 7.35, p < 0.001). Monthly variation was more pronounced for older people (mean daily AMI deaths of people older than 70 years was 3.53 in June and 7.03 in December; p < 0.001) and of only marginal significance for younger people. The best predictor of daily AMI deaths was the average temperature of the previous seven days; the relation between daily AMI deaths and seven-day average temperature (R2  =  0.109, p < 0.001) was U-shaped. Considering monthly AMI death rates, only mean monthly humidity was independently associated with total deaths from AMI (R2  =  0.541, p  =  0.004). Conclusion: Ambient temperature is an important predictor of AMI mortality even in the mild climate of a Mediterranean city like Athens, its effects being predominantly evident in the elderly. Mean monthly humidity is another meteorological factor that appears to affect monthly numbers of AMI deaths. These findings may be useful for healthcare and civil protection planning.

Detection of hypertensive patients at risk for paroxysmal atrial fibrillation during sinus rhythm by computer-assisted P wave analysis

OBJECTIVE AND METHODS To determine whether hypertensive patients at risk for paroxysmal atrial fibrillation (AF) could be detected while in sinus rhythm, a computer-based 12-lead surface electrocardiogram was recorded in 50 hypertensive patients with history of paroxysmal AF (group A) and in 60 hypertensive patients without history of AF (group B). The maximum P-wave duration (P(maximum)), the minimum P-wave duration (P(minimum)), P-wave dispersion (Pdispersion = Pmaximum Pminimum), adjusted P-wave dispersion (APdispersion = Pdispersion/square root of the number of measurable leads), mean P-wave duration (mean P) and the standard deviation of the P-wave duration in all measured leads (SDP) were calculated. RESULTS Pdispersion, APdispersion and SDP were significantly higher in group A than in group B (Pdispersion, 52 +/- 19 versus 41 +/- 15 ms, P< 0.001; APdispersion, 15.2 +/- 5.5 versus 11.9 +/- 4.6 ms, P< 0.001; SDP, 16 +/- 5 versus 13 +/- 5 ms, P < 0.001). P(minimum), mean P and left ventricle ejection fraction (LVEF) were significantly lower in group A than in group B (Pminimum, 79 +/- 18 versus 91 +/- 13 ms, P < 0.001; mean P, 108 +/- 18 versus 116 +/- 13 ms, P= 0.005; LVEF, 64 +/- 5 versus 69 +/- 8%, P< 0.001). Pminimum, Pdispersion, mean P, SDP, APdispersion and LVEF were found to be significant univariate predictors of paroxysmal AF, whereas only Pminimum (P< 0.001) remained a significant independent predictor of paroxysmal AF in the multivariate analysis. CONCLUSION Hypertensive patients at risk for paroxysmal AF could be detected while in sinus rhythm by computer-assisted electrocardiographic P-wave analysis.

P Wave Dispersion: A Valuable Electrocardiographic Marker for the Prediction of Paroxysmal Lone Atrial Fibrillation

Background: The prolongation of atrial conduction time and the inhomogeneous propagation of sinus impulses are well known electrophysiological characteristics in patients with paroxysmal atrial fibrillation.

Monitoring of arterial stiffness indices by applanation tonometry and pulse wave analysis: reproducibility at low blood pressures.

Objective. Aortic pulse wave analysis (PWA) reveals valuable information related to several hemodynamic characteristics mainly in normotensive and hypertensive patients. The main indices determined by PWA are augmentation index (AI) and reflection time index (RTI), which provide an indirect estimate of arterial stiffness and pulse wave velocity. The objective of the present study was to assess the reproducibility of aortic AI and RTI obtained by an automated and commercially available system (SphygmoCor) applied in patients with low blood pressures where such data are lacking. Methods. The study population consisted of 19 patients with cardiogenic shock due to acute myocardial infarction who underwent mechanical assistance with intraaortic balloon pump. Aortic pressure waveforms were derived from peripheral waveforms—recorded by applanation tonometry of the radial artery—by applying generalized transfer functions. On every occasion, a well-trained operator performed two measurements with 2 min interval. Multiple pairs of measurements were obtained per patient in order to study a wide range of different hemodynamic conditions. Thus, a total of 91 pairs of measurements were performed and analyzed using Bland-Altman plots. Results. AI and RTI ranged within 30–184% and 10–27%, respectively. Within-observer difference was 0.10 ± 5.82% for aortic AI and 0.14 ± 1.2% for RTI. Conclusion. Pulse wave analysis and radial artery tonometry can be used to measure AI and RTI with satisfactory reproducibility even in low blood pressures. Ongoing research is required to establish PWA utility in clinical practice especially at patients with low blood pressures.

Hour-to-hour and week-to-week variability and reproducibility of wave reflection indices derived by aortic pulse wave analysis: implications for studies with repeated measurements.

Background Wave reflections are implicated increasingly in clinical research. Aims The purpose of the present study was to investigate whether wave reflection indices are reproducible when measured repeatedly (more than twice) at longer time intervals, namely hour-to-hour and week-to-week, in healthy subjects; something that has not yet been examined. Methods Bland–Altman plots, the interclass correlation coefficients (ICC) and coefficient of variation were used for this purpose. Two series, with measurements repeated in triplicate, were performed in 22 healthy subjects: the first at intervals of 1 h and the second at 1-week time intervals. Augmentation index (AIx), heart rate-corrected AIx (AI@75) and arrival time of reflected waves at the central aorta (tr) were calculated by aortic pulse wave analysis. Results AIx and AI@75 presented very good to excellent reproducibility (ICC = 0.86) for hour-to-hour repeated measurements, while tr was also highly reproducible (ICC = 0.79). AIx, AI@75 and tr were substantially reproducible when measured repeatedly with 1-week intervals, providing ICCs greater than 0.70. Bland–Altman plots confirmed these results, indicating that more than 90% of AIx, AI@75 and tr measurements fell within two standard deviations of the mean difference. Conclusions Wave reflections are substantially reproducible even when measurements repeated in triplicate are performed at longer time intervals (hours and weeks). A quantifiable amount of variation was reported, which should be taken carefully into consideration in interventional studies with repeated measurements and in observational studies investigating differences or correlations of these indices.

The paradoxical association of common polymorphisms of the renin-angiotensin system genes with risk of myocardial infarction.

Background The insertion/deletion polymorphism of the angiotensin-converting enzyme (ACE) and the A1166C polymorphism of the angiotensin-II AT1 receptor (AT1R) have been extensively investigated as possible risk factors for myocardial infarction (MI). Design and methods Genetic association, case-control study, specifically designed to investigate the association of the above-mentioned polymorphisms with risk of MI in a homogeneous, low coronary risk, Caucasian population. The study population consisted of 1603 consecutive patients with acute MI who were recruited from nine clinics, located in three cities, and 699 unrelated adults who were randomly selected from the city catalogues. Results In univariate analysis, the DD genotype was found to be more prevalent among controls (40.8 vs. 35.2%, P = 0.011). In multivariate analysis adjusted for age, gender, smoking status, diabetes mellitus, hypercholesterolemia, hypertension and family history of coronary artery disease, the presence of the DD genotype was independently and negatively associated with risk of AMI (RR = 0.743, 95% CI = 0.595–0.927, P = 0.008). The CC genotype was not found to be significantly associated with risk of MI, either in univariate (6.2 vs. 6.4%, P = 0.856), or in multivariate analysis adjusted for the same confounders (RR = 0.743, 95% CI = 0.473–1.167, P = 0.197). Conclusions Contrary to previous reports, in this study the DD genotype of the ACE gene, but not the CC genotype of the AT1R gene, was associated with a lower risk of MI. Our results emphasize the complexity of genotype-phenotype interactions in the pathogenesis of ischaemic heart disease and question the previously hypothesized role of the DD genotype on risk of acute myocardial infarction.

Spatial aspects of ventricular repolarization in postinfarction patients.

DILAVERIS, P., et al.: Spatial Aspects of Ventricular Repolarization in Postinfarction Patients. QT dispersion has been proposed to reflect the heterogeneity of ventricular repolarization, but a poor reproducibility limits its clinical usefulness. Spatial vectorcardiographic descriptors constitute a novel approach to quantify ventricular repolarization. To test the ability of vectorcardiographic descriptors to discriminate among different subsets of postinfarction patients, 50 consecutively recruited patients with acute MI, 50 patients with history of an old (> 6 months) MI, and 50 healthy controls were evaluated. The maximum and minimum QT and JT intervals and QT and JT dispersion were manually measured from a digitally recorded 12‐lead ECG. X, Y, and Z leads were reconstructed from the 12‐lead ECG. The amplitude of the maximum spatial T vector (spatial T amplitude), the angle between the maximum spatial QRS and T vectors (spatial QRS‐T angle), and the frontal plane QRS‐T angle were automatically calculated. The spatial T amplitude and the spatial QRS‐T angle did not differ between patients with a recent and those with an old MI (P = 1). QT dispersion was significantly lower in patients with an old MI than in patients with a recent one (P = 0.002). The spatial repolarization descriptors showed better short‐term reproducibility than the dispersion indices. In conclusion, the spatial T amplitude and the spatial QRS‐T angle are accurate measures of ventricular repolarization that do not differ between patients with recent and those with old MI. The different QT dispersion values observed in this study between the two post‐MI groups should be considered cautiously because of the low accuracy of the manual measurements.

Myocardial mechanics for the early detection of cardiac sarcoidosis

Background: Speckle tracking has emerged as valuable tool for comprehensive assessment of regional myocardial function, providing angle-independent measurements of ventricular strain. Aim of this study was to evaluate left ventricular (LV) function in patients with newly diagnosed sarcoidosis, utilizing the novel method of 2D speckle tracking. Methods: Forty one patients with sarcoidosis and unremarkable medical history of cardiovascular disease, as well as 20 healthy age- and gender-matched controls underwent echocardiographic study. Apical 4-,2-,3- chamber as well as short axis acquisitions were made. In addition to conventional 2D, Doppler and TDI measurements, speckle tracking echocardiography was applied and LV global longitudinal strain was derived from the obtained images. Moreover, LV base and apex rotation angles were assessed from which LV twist was derived. Results: The mean age of patients (17 men) was 41 ± 6.5 years old. Compared with controls, patients had similar conventional 2D and Doppler measurements. TDI revealed increased E/E9 in the patient group vs control group (8.72 ± 1.65 vs 4.6 ± 1.32, p Conclusions: Speckle tracking echocardiography revealed impaired strain and rotational indices, implying elevated filling pressures of the left ventricle. This may represent a sign of myocardial involvement in patients with sarcoidosis. Therefore deformation imaging could be valuable adjunct for screening.