Comparison of left atrial size and pulmonary capillary pressure with P wave of electrocardiogram

Electrocardiographic deep terminal negativity of the P wave in V1 and risk of mortality: the National Health and Nutrition Examination Survey III

INTRODUCTION

Deep terminal negativity of P wave in V1 (DTNPV1), defined as negative P prime larger than one small box (1 mm, or 0.1 mV), could be easily detected by simple visual inspection of the resting 12-lead ECG. The objective of this study was to determine the relationship between DTNPV1 and all-cause-, cardiovascular disease (CVD), and ischemic heart disease (IHD) mortality in the National Health and Nutrition Examination Survey III (NHANES III).

METHODS AND RESULTS

After exclusion of participants with atrial fibrillation and missing data, DTNPV1 was automatically measured from standard 12-lead ECG in 8,146 participants. Minnesota and Novacode algorithms were used for the determination of major and minor ECG abnormalities. National Death Index was used to identify the date and cause of death. During a median follow-up of 13.8 years, a total of 2,975 deaths (1,303 CVD and 742 IHD deaths) occurred. After adjustment for age, gender, race/ethnicity, IHD, heart failure, chronic obstructive pulmonary disease, cancer, diabetes, body mass index, smoking, dyslipidemia, hypertension, use of antihypertensive and lipid-lowering medications, and ECG abnormalities, DTNPV1 was associated with significantly increased risk of all-cause death (HR [95% CI]: 1.30 [1.10, 1.53]; P = 0.002), CVD death (HR [95% CI]: 1.36 [1.08, 1.72]; P = 0.010), and IHD death (HR [95% CI]: 1.36 [1.00, 1.85]; P = 0.047).

CONCLUSION

In a large sample of the adult United States population, DTNPV1 is independently associated with increased risk of death due to all-cause, CVD, and IHD, findings suggesting its potential usefulness as a simple marker to identify individuals at risk of poor outcomes.

P-wave dispersion and heart rate variability in children with mitral valve prolapse

Previous studies have reported that patients with mitral valve prolapse (MVP) may display autonomic dysfunction. Measurement of heart rate variability (HRV) and P-wave dispersion (PWD) may provide insights into the functional state of the autonomic nervous system. Heart rate variability (HRV) has been used as a noninvasive marker of autonomic activity. However, to the authors' knowledge, PWD has not been studied in the context of MVP. This study aimed to examine HRV and PWD in patients with MVP and to determine whether differences exist between symptomatic and asymptomatic patients. The study population consisted of 54 healthy children (17 boys and 37 girls) ages 6-18 years and 76 patients with MVP (20 boys and 56 girls) ages 6-18 years. The duration and dispersion of the P-wave were measured by surface 12-lead electrocardiograms (ECGs). Heart rate variability was quantified using both time-domain and frequency-domain analyses of Holter ECGs. The minimum duration of the P-wave was significantly lower in the MVP patients (42.4 ± 10.0 ms) than in the control subjects (54.4 ± 12.8 ms) (p < 0.01), and the PWD was significantly increased in the MVP group (42.7 ± 10.8 ms) compared with the control subjects (31.8 ± 10.9 ms) (p < 0.01). However, no significant differences were found between the symptomatic and asymptomatic patients. In addition, the HRV parameters were not statistically different between the two groups. In conclusion, although HRV parameters were not significantly different between the MVP and control groups, the findings show that PWD was increased for the children with MVP. However, no relationship could be established between PWD and clinical symptoms.

Accuracy of electrocardiographic criteria for atrial enlargement: validation with cardiovascular magnetic resonance

BACKGROUND

Anatomic atrial enlargement is associated with significant morbidity and mortality. However, atrial enlargement may not correlate with clinical measures such as electrocardiographic (ECG) criteria. Past studies correlating ECG criteria with anatomic measures mainly used inferior M-mode or two-dimensional echocardiographic data. We sought to determine the accuracy of the ECG to predict anatomic atrial enlargement as determined by volumetric cardiovascular magnetic resonance (CMR).

METHODS

ECG criteria for left (LAE) and right atrial enlargement (RAE) were compared to CMR atrial volume index measurements for 275 consecutive subjects referred for CMR (67% males, 51 +/- 14 years). ECG criteria for LAE and RAE were assessed by an expert observer blinded to CMR data. Atrial volume index was computed using the biplane area-length method.

RESULTS

The prevalence of CMR LAE and RAE was 28% and 11%, respectively, and by any ECG criteria was 82% and 5%, respectively. Though nonspecific, the presence of at least one ECG criteria for LAE was 90% sensitive for CMR LAE. The individual criteria P mitrale, P wave axis < 30 degrees , and negative P terminal force in V1 (NPTF-V1) > 0.04s.mm were 88-99% specific although not sensitive for CMR LAE. ECG was insensitive but 96-100% specific for CMR RAE.

CONCLUSION

The presence of at least one ECG criteria for LAE is sensitive but not specific for anatomic LAE. Individual criteria for LAE, including P mitrale, P wave axis < 30 degrees , or NPTF-V1 > 0.04s.mm are highly specific, though not sensitive. ECG is highly specific but insensitive for RAE. Individual ECG P wave changes do not reliably both detect and predict anatomic atrial enlargement.

Contribution of left atrial pressure and dimension to signal-averaged P-wave duration in patients with chronic congestive heart failure

In a group of patients with chronic heart failure, a longer P-wave duration on signal-averaged electrocardiogram was found in those patients with higher pulmonary capillary wedge pressure, whereas the left atrium end-systolic diameter was not significantly different. Furthermore, an acute reduction in pulmonary capillary wedge pressure induced by sodium nitroprusside infusion was associated with a reduction in P-wave duration.

Effects of autonomic stimulation and blockade on signal-averaged P wave duration

OBJECTIVES

This study sought to evaluate the effects of autonomic stimulation and blockade on the signal-averaged P wave duration.

BACKGROUND

Signal-averaged P wave duration has been shown to have prognostic implications for patients prone to develop atrial fibrillation, but autonomic influences on the signal-averaged P wave duration have not been studied.

METHODS

In 14 healthy volunteers (8 men, 6 women; mean [ +/- SD] age 28.5 +/- 4.8 years, range 22 to 38), signal-averaged P wave duration was measured on day 1 at baseline, during sympathetic stimulation with infusions of epinephrine (50 ng/kg body weight per min) and isoproterenol (50 ng/kg per min), beta-blockade with propranolol (0.2 mg/kg) and autonomic blockade with propranolol followed by atropine (0.04 mg/kg). On a second day, 10 of the 14 subjects returned for repeat baseline recordings and recordings during parasympathetic blockade with atropine (0.04 mg/kg). Signal averaging was performed using a P wave template. Both unfiltered and filtered (least-squares fit filter with 100-ms window) P wave durations were measured. Day to day and interobserver variability were assessed by calculation of intraclass correlation coefficients.

RESULTS

The mean ( +/- SD) baseline filtered P wave duration on day 1 was 141 +/- 10 ms. Isoproterenol infusion significantly shortened the P wave duration to 110 +/- 16 ms (p < 0.001), and epinephrine resulted in significant prolongation to 150 +/- 10 ms (p < 0.05). Beta-adrenergic blockade increased the P wave duration to 153 +/- 10 ms (p < 0.005). Autonomic blockade shortened the P wave duration to 143 +/- 16 ms (p < 0.05 vs. beta-blockade). On the second day, the mean baseline P wave duration was slightly longer (144 +/- 10 ms, p < 0.02). Parasympathetic blockade with atropine resulted in mild shortening of the P wave duration to 136 +/- 15 ms (p < 0.1). Interobserver reproducibility was excellent (intraclass correlation coefficient 0.99). Day to day reproducibility was good (intraclass correlation coefficient 0.56).

CONCLUSIONS

The signal-averaged P wave duration is not a fixed variable because it may change significantly under different autonomic conditions. This has important implications for the application of this test to the heterogeneous population susceptible to atrial fibrillation.

Relationship between Doppler left ventricular diastolic filling indexes and the electrocardiographic criteria for left atrial enlargement

Traditional electrocardiographic (ECG) criteria for left atrial enlargement (LAE) emphasize the increased amplitude and width of the corresponding component of the hypertrophied atrium. Although a correlation exists between LAE and ECG criteria, a cause-and-effect relationship has not been conclusively demonstrated. Because the diastolic properties of the left ventricle directly influence left atrial emptying, these properties might also influence the ECG diagnosis of LAE. Therefore, the authors hypothesized that the ECG criteria for LAE are influenced by diastolic properties of the left ventricle as defined by Doppler-derived parameters.

Electrocardiographic diagnosis of chamber enlargement

The purpose of this article is to review the changing role of the electrocardiogram in the diagnosis of cardiac chamber enlargement. Electrocardiographic criteria for the diagnosis of ventricular hypertrophy and atrial enlargement are reviewed in relation to autopsy, angiographic, echocardiographic and imaging findings. The electrocardiographic theory underlying the recognition of hypertropphy or dilation incorporates a number of sound physical principles that may lead to meaningful correlations with the tissue mass, chamber diameter and intracardiac blood volume. However, there are limiting factors related to the variable orientation of the heart in the chest, variable extracardiac factors and nonspecificity of each depolarization and repolarization abnormality used in the diagnosis of hypertrophy or dilation. This explains the superiority of the new noninvasive methods, in particular echocardiography, in the diagnosis of hypertrophy. Echocardiography is superior to electrocardiography in the detection of mild hypertrophy, and is more useful in the serial follow-up of changes during progression or regression of chamber enlargement.

Exercise P-vector magnitude changes in angina pectoris: Frank-Vectorcardiographic and hemodynamic correlations

Multistage bicycle ergometer exercise testings with Frank vectorcardiogram and M-mode echocardiogram were performed on 12 patients with effort angina pectoris. The left atrial and left ventricular end-diastolic volume (LAV and LVEDV) were calculated as a cube of the left atrial and left ventricular end-diastolic dimension. The mean pulmonary artery wedge pressure (mPAWP) was measured with a Swan-Ganz catheter during the testing. At peak exercise a statistically significant increase was observed in mPAWP (p less than 0.001), LAV (p less than 0.005), the maximal horizontal P-vector magnitude (Hmax) (p less than 0.05) and the percent change in Hmax (%Hmax). %Hmax showed a significant correlation with the increment of mPAWP (delta mPAWP) (r = 0.66, p less than 0.05), the increment of LVEDV (delta LVEDV) (r = 0.83, p less than 0.01) and the increment of LAV (delta LAV) (r = 0.81, p less than 0.001). Multiple regression analysis was performed on %Hmax as a dependent variable with delta LAV, delta mPAWP, and the increment of heart rate (delta HR) as independent variables (r = 0.84, p less than 0.05), but the partial correlation coefficients of delta mPAWP and delta HR were not significant. The present study demonstrated that the increase in Hmax had a close relationship with the increase in mPAWP and LVEDV and that the preload of the left ventricle during exercise-induced anginal attack could be predicted noninvasively by %Hmax. The increase in Hmax was thought to be due to the increase in LAV during anginal attack.

Sensitivity and specificity of commonly used electrocardiographic criteria for left atrial enlargement determined by M-mode echocardiography

To assess the sensitivity and specificity of 6 commonly used electrocardiographic criteria for left atrial (LA) enlargement, the rest ECGs of 99 patients in normal sinus rhythm were analyzed. Fifty-seven of the patients had LA enlargement and 42 had a normal LA dimension as determined by M-mode echocardiography. The 6 criteria studied and their respective sensitivities and specificities were as follows: (1) duration of the negative phase of the P wave in lead V1 greater than 40 ms: sensitivity, 83%; specificity, 80%; (2) notched P wave in any standard lead with an interpeak duration greater than 40 ms: sensitivity, 15%; specificity, 100%; (3) P terminal force (depth X duration of the terminal portion of the P wave) in lead V1 more negative than -0.04 mm X s: sensitivity, 69%; specificity 93%; (4) depth of the negative phase of the P wave in lead V1 greater than or equal to 1 mm: sensitivity, 60%; specificity, 93%; (5) total P-wave duration greater than 110 ms in any standard lead: sensitivity, 33%; specificity, 88%; (6) total P wave duration/P-R interval duration greater than 1.6: sensitivity, 31%; specificity, 64%. Combining 2 or more of these criteria did not substantially improve sensitivity and specificity.

Assessment of electrocardiographic criteria for left atrial enlargement in childhood

Ninety children, aged 1 day to 18 years (median 7 months), with electrocardiographic or echocardiographic evidence of left atrial (LA) enlargement were selected to determine if electrocardiographic criteria accurately reflected increased LA dimension as determined by echocardiography. Four cardiac defects known to produce LA enlargement were chosen: ventricular septal defect (24 patients), patient ductus arteriosus (25 patients), cardiomyopathy (27 patients) and mitral regurgitation (14 patients). Different electrocardiographic criteria for LA enlargement were assessed. The data indicated that the overall sensitivity and predictive value of the ECG to detect LA enlargement were 40 and 85%, respectively. The ECG and echocardiogram failed to agree in 62% of the patients. The most predictive variable for LA enlargement was the presence of a notched P wave in the limb leads with a large negative terminal deflection in lead V1. The sensitivity of ECG was highest in patients with chronic LA overload status, in mitral regurgitation (77%), cardiomyopathy (50%) and ventricular septal defect (54%). The results show that in the pediatric population, electrocardiographic criteria are moderately predictive for LA enlargement but not as sensitive as generally believed.

The terminal P wave vector in lead V1 of the electrocardiogram in healthy young airmen

The terminal P wave vector in lead V1 of the electrocardiograph (V1PTV) was abnormal in 93 (3.2%) of 3119 healthy recruits into the Royal Air Force of mean age 19 (SD 4) years. The inference that an abnormal V1PTV indicates left atrial enlargement should be made with caution in otherwise healthy young men.

The effect of left atrial histology and dimension on P wave morphology

This study correlates left atrial appendage cell size, atrial fibrosis and echocardiographic (echo) measurement of left atrial size with P wave morphology. Twelve patients with known mitral valve disease had echo measurements of left atrial size with P wave morphology. Twelve patients with known mitral valve disease had echo measurements of left atrial size prior to mitral valve surgery; patients had varying degrees of left atrial enlargement. The left atrial appendage, removed at the time of surgery, was stereologically assessed for percent fibrosis and the diameters of 50 cells were measured and averaged. These factors were correlated with P wave amplitude and duration in lead II, greatest length in any led, PR segment (end of P wave to onset of QRS), P to PR segment ratio (in lead II) and the PR interval. There was a good correlation of left atrial cell diameter with P wave amplitude (r = .69, p = 0.01). There was a good inverse correlation of percent fibrosis with the PR segment (r = -.72, p = 0.01) and a direct correlation of fibrosis with the ratio of P wave length to PR segment (r = .67 p = 0.01). There was a trend for percent fibrosis to correlate with PO wave duration but not height. No correlation was noted for any of the P wave characteristics and left atrial size. This study demonstrates that there is a correlation of P wave height with cell diameter and P wave length and PR segment with fibrosis. These data are helpful in understanding the electrocardiographic P wave.

Electrocardiographic recognition of left atrial enlargement

The ECG is widely used as a screening test for left atrial enlargement (LAE). Surprisingly, the most widely used criterion of LAE, the P-terminal force in lead V1 (PTF-V1) has not been systematically evaluated to determine the optimal level of PTF-V1 for detection of LAE in clinical populations. Accordingly, we examined the relationship between PTF-V1 and left atrial size by echocardiogram in 361 patients and performed a Bayesian analysis of test performance in populations with a varying prevalence of LAE. As PTF-V1 increased from greater than or equal to 0.03 to greater than or equal to 0.08, sensitivity in the 82 patients with LAE (LA dimension greater than 40 mm) fell from 51% to 23%, and specificity rose from 70% to 93%. In our study population (LAE prevalence = 23%), diagnostic performance of criteria was: PTF-V1 greater than or equal to 0.03 greater than or equal to 0.04 greater than or equal to 0.05 greater than or equal to 0.06 greater than or equal to 0.08 Positive Predictive Accuracy 33 46 52 58 50 Negative Predictive Accuracy 83 83 84 83 80 Per Cent Correct Diagnosis 66 76 78 80 77 Positive predictive accuracy and per cent correct diagnosis improved progressively as PTF-V1 rose from greater than or equal to 0.03 to greater than or equal to 0.06, but fell at greater than or equal to 0.08. Applying our sensitivity and specificity data to Bayesian analysis, PTF-V1 greater than or equal to 0.06 performed best in all populations with prevalence of LAE less than or equal to 50%. We conclude that use of PTF-V1 greater than or equal to 0.06 is superior to the standard criterion of PTF-V1 greater than or equal to 0.04 for all purposes ranging from screening of a general population to evaluation of diseased individuals whose likelihood of LAE ranges up to 50%.

Reassessment of electrovectorcardiographic signs of left atrial enlargement

Echocardiographic left atrial size was correlated with 27 electrovectorcardiographic parameters in 93 subjects. In 20 of them hemodynamic studies, including calculation of the left atrial volume, were performed. Subjects were divided into four groups as follows: Group I, 21 healthy subjects; group II, 45 patients with heart disease but no left atrial enlargement; group III, 15 patients with heart disease and left atrial size from 4.1 to 5 cm; and group IV, 12 patients with heart disease and a left atrial size exceeding 5 cm. A good correlation was found between left atrial size and the following parameters: Duration of P wave in standard lead II, voltage of both terminal forces of P wave in lead V1 and its maximal vector in the frontal and sagittal planes. A new index (duration/voltage of P wave in lead II) was postulated, which showed an excellent correlation with left atrial size (p less than 0.001). In all cases the superposition between groups was excessive. These findings indicate the limitations of the classical patterns and raise interest in new parameters concerning the electrocardiographic diagnosis of left atrial enlargement.

Left atrial size and left ventricular function in coronary artery disease: an echocardiographic-angiographic correlative study

M-mode echocardiography was used to determine left atrial size in 100 patients with coronary artery disease undergoing cardiac catheterization. Patients were divided in two groups on the basis of left atrial diameter (greater than or equal to 40 mm in 40 patients and less than 40 mm in 60). Patients with larger left atria had a higher frequency of electrocardiographic evidence of left atrial abnormality (p less than 0.01) and myocardial infarction (p less than 0.001). Pulmonary capillary wedge and left ventricular end-diastolic pressures were higher (p less than 0.005) in patients with larger left atria. An abnormal end-diastolic volume (greater than 100 ml/M2) was observed in 13 patients with enlarged left atria compared to none with normal left atrial size (p less than 0.001). Triple vessel disease was more frequent (63% vs 32%) and single vessel disease less frequent (10% vs 37%) in patients with larger left atria (p less than 0.005). Abnormal left ventricular contractile patterns were noted in 45% of patients with normal left atrial diameters compared to 80% in those with an enlarged left atrium (p less than 0.001). An abnormally low ejection fraction (less than 0.5) was observed in 25% and 80%, respectively, in patients with normal and enlarged left atria (p less than 0.001). Of 58 patients with normal ejection fractions, only 17% had left atrial diameters greater than or equal to 40 mm compared to 71% of 42 patients with abnormally low ejection fractions (p less than 0.001). Of 18 patients with left atrial diameters greater than 42 mm, only two had normal ejection fractions. The mean ejection fraction for patients with left atrial diameters less than 40 mm was 0.63 +/- 0.13 compared to 0.41 +/- 0.18 for those with diameters greater than or equal to 40 mm (p less than 0.001). The sensitivity, specificity, and predictive value for an enlarged left atrium in identifying an abnormal ejection fraction were, respectively, 71, 83, and 75%. These findings indicate that M-mode echocardiographic left atrial enlargement is a useful marker of advanced hemodynamic and angiographic abnormality in patients with coronary artery disease.

Electrocardiographic left atrial enlargement. Electrophysiologic, echocardiographic and hemodynamic correlates

The mechanism of the electrocardiographic pattern termed left atrial enlargement was evaluated in 21 patients. Left atrial size and pressure as well as interatrial conduction were correlated with electrocardiographic left atrial enlargement using echocardiography, mean pulmonary capillary wedge pressure and activation time from the P wave to the coronary sinus. In the group as a whole only prolongation of interatrial conduction time was consistently related to the electrocardiographic pattern of left atrial enlargement; left atrial size or pressure was not predictably abnormal in patients with this pattern. Five patients had neither elevation of pulmonary capillary wedge pressure nor echocardiographic evidence of an enlarged left atrium. When the etiologic type of heart disease was analyzed, an enlarged left atrium correlated with electrocardiographic left atrial enlargement only in patients with rheumatic mitral valve disease (eight of nine patients). Elevated pulmonary capillary wedge pressure correlated with electrocardiographic left atrial enlargement in all four patients with cardiomyopathy. In patients with coronary artery disease the electrocardiographic pattern was unrelated to either left atrial pressure or volume overload. Thus, the electrocardiographic pattern termed left atrial enlargement appears to represent an interatrial conduction defect that can be produced by a variety of factors.

Correlation of mean pulmonary artery wedge pressure, left atrial dimention, and PTF-V1 in patients with acute myocardial infarction

The mean pulmonary artery wedge pressure (PAWP), left atrial dimension (LAD) by echocardiography, and PTF-V1 in the electrocardiogram were correlated with each other in 16 patients with acute myocardial infarction in the control period and after therapeutic intervention with either Dextran or furosemide and/or nitroprusside. No significant correlation was found between a normal control PAWP and the LAD. An increased control PAWP correlated well with an increased LAD (r = 0.98). No significant correlation was found between the LAD and the PAWP whether normal or elevated after therapeutic intervention. No significant correlation was found between the PAWP whether normal or elevated and the PTF-V1. No significant correlation was found between the LAD and the PTF-V1. We conclude in acute myocardial infarction 1) the PTF-V1 is not useful in assessing PAWP before or after therapeutic intervention, 2) the LAD correlates poorly with a normal control PAWP but correlates well with an elevated control PAWP, and 3) the LAD cannot be used to assess PAWP after therapeutic intervention.