Evaluation of ECG criteria for P-wave abnormalities

Predictor of A4 amplitude using preprocedural electrocardiography in patients with leadless pacemakers

BACKGROUND

Based on historical studies of leadless pacemakers (LPs), high atrioventricular synchrony (AVS) with mechanical sensing-based VDD pacing is largely influenced by A4 amplitude. A limited study investigated the predictors of A4 amplitude using clinical and echocardiographic parameters.

OBJECTIVE

The purpose of this study was to investigate the predictors of A4 amplitude preoperatively to select patients who could benefit the most from AVS among patients with VDD LPs (Micra-AV, Medtronic).

METHODS

Data from patients who received Micra-AV implantations from November 2021 to August 2023 at Tottori University Hospital were analyzed. Twelve-lead electrocardiography and transthoracic echocardiography were performed before the Micra-AV implantations. To assess the electrical indices associated with the A4 signal, electrocardiographic morphologic P-wave parameters were analyzed, including P-wave duration, P-wave amplitude, maximum deflection index (MDI), and P-wave dispersion.

RESULTS

A total of 50 patients who underwent Micra-AV implantations (median age 84 years; 64% male) were included and divided into 2 groups based on the median value of A4 amplitude, the high-A4 group (A4 amplitude >2.5 m/s2; n = 26), and low-A4 group (A4 amplitude ≤2.5 m/s2; n = 24). There was a significant difference between the high-A4 and low-A4 groups with regard to left ventricular ejection fraction (P = .01), P-wave dispersion (P = .01), and MDI (P <.001). Multivariate logistic analysis revealed that lower MDI was an independent predictor of high A4-amplitude (odds ratio 0.78; 95% confidence interval 0.67-0.92; P = 0.003).

CONCLUSION

Preoperative electrocardiographic evaluations of P-wave morphology may be useful for predicting A4 amplitude. MDI was the only independent A4 amplitude predictor that seemed promising for selecting Micra-AV patients.

The Impact of Pulmonary Vein Anatomy on P-Wave Appearance during Sinus Rhythm: Cardiac Computed Tomography Study

Electrocardigraphy remains a first-line evaluation method for cardiac electrical activity, recorded from the body surface. Since atrial activation is seen on the ECG as a P-wave, several factors are known to impact the appearance of the P-wave, such as the direction of electric impulse, conduction abnormalities, and anatomical characteristics of the atria. This retrospective study aimed to find statistically significant associations between the anatomy of pulmonary veins (PVs) observed in cardiac computed tomography (CT) and P-wave appearance during sinus rhythm on resting ECG. For each patient, a resting 12-lead ECG was recorded, and the field of analysis was P-wave-its duration, morphology, and axis. The evaluation of the CT scan recordings was performed by creating 3D models of the left atrium and analyzing the anatomy of the PVs and left atrial appendages (LAA). Noteworthy correlations were found: anatomy of the left PVs showed an association with LAA volume, LAA morphology, and P-wave notching in lead II. The right PVs demonstrated a relation with the P-wave axis and amplitude. Although these correlations cannot be classified as strong, the results not only expand understanding about discussed variables but also suggest the presence of a subtle and complex relationship, that warrants further exploration.

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.

Right Bundle Branch Block: A New Parameter Revealing the Progression Rate of Mitral Stenosis

BACKGROUND

Mitral stenosis has a generally slow but often variable clinical course. However, the factors that influence the rate of stenosis progression have not been completely identified. The aim of this study was to evaluate whether right bundle branch block (RBBB) may be related to the rapid progression of pure mitral stenosis besides echocardiographic parameters.

METHODS

Four hundred and thirty-six patients (300 females) were reviewed retrospectively. The patients were classified according to RBBB existence in electrocardiography: group A included 83 patients with RBBB existence, and group B contained 353 patients without RBBB. The patients were further classified as subjects who had an echocardiographic valve score < or =8 (325 patients, group 1) and those with a valve score >8 (111 patients, group 2).

RESULTS

The mean age of the patients was similar in groups A and B. In group A, the mean mitral valve gradient was higher (12.63 +/- 4.43 vs. 10.58 +/- 3.37 mm Hg; p < 0.0001), the mitral valve area smaller (1.05 +/- 0.2 vs. 1.14 +/- 0.52 cm2; p = 0.011), and the systolic pulmonary artery pressure higher (53.5 +/- 16.2 vs. 46.9 +/- 13.2 mm Hg; p = 0.001) than in group B. The mean age and mitral valve area were similar in groups 1 and 2. The mean mitral valve gradient (10.5 +/- 3.7 vs. 12.3 +/- 3.0 mm Hg; p < 0.0001) and systolic pulmonary artery pressure were higher in group 2 (46.7 +/- 13.3 vs. 52.5 +/- 15 mm Hg; p < 0.0001).

CONCLUSION

These findings indicate that RBBB existence correlates with the severity of the disease and the grade of valve calcification in moderate and severe pure mitral stenosis.

The electrocardiogram in the primary care office

A 12-lead electrocardiogram (ECG) graphically displays the heart's electrical activity. It is the most common clinical tool for detection and diagnosis of heart disease, and is especially useful for detecting conditions related to abnormalities of cardiac rhythm. ECG should be considered in patients who have known cardiovascular disease or an increased risk for it. The responsibility for correctly interpreting an ECG lies with the physician, who should be able to recognize patient-dependent errors, operator-dependent errors, and artifact. Current ECG tracings should always be compared with previous tracings. Following a specific routine and methodical analysis of the data will ensure an accurate interpretation result. In the worst-case scenario, they can always be faxed or transmitted for inter-consultation with a more experienced reader.

Peripheral Edema Masks the Diagnoses of P Pulmonale, P Mitrale, and Biatrial Abnormality: Clinical Implications for Patients With Heart Failure

Peripheral edema (PED) impacts the size of the electrocardiogram, attenuating the amplitude and duration of QRS complexes and P waves. Diagnostic configurations of P pulmonale (Pp), P mitrale (Pm), and biatrial abnormality (Pb) are based on measurements of the amplitude and duration of the P waves. To investigate whether PED masks the diagnoses of Pp, Pm, and Pb, 15 patients (nine who suffered PED and six who did not gain weight during hospitalization, who served as controls) were studied. Of nine patients with PED, one had Pp, four had Pm, and four had Pb on admission, but such configurations were abolished after development of PED, except in one patient with Pm. Of six controls, one patient had Pp, three had Pm, and two had Pb, both on admission and at discharge. There was no difference in sex (p=0.61) or age (p=0.27) between the patients with PED and the controls; however, patients with PED were sicker and eventually died, while none of the controls did so. Electrocardiographic atrial abnormalities can be masked by PED, resulting from the attenuation of P waves and mediated by a decrease in the electrical impedance of the body's volume conductor due to water overload. These have clinical implications for patients with heart failure.

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 angina like 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.

Abnormalities of electrocardiographic P wave morphology and their relation to electrophysiological parameters of the atrium in patients with sick sinus syndrome

We examined the incidence of long P wave duration in lead II and increased P terminal force in lead V1 (PTFV1), and their relationship to electrophysiological findings of atrial muscle in 34 patients with sick sinus syndrome (SSS). Patients were divided into three groups: Group I, consisting of 20 patients with various cardiac arrhythmias other than SSS and paroxysmal atrial fibrillation (PAF) who served as controls; Group II, consisting of 18 patients with SSS but without PAF; and Group III consisted of 16 patients with SSS and PAF. P wave duration was significantly longer in Group III (122 +/- 11 ms, mean +/- SD, P < 0.0001) and Group II (111 +/- 15 ms, P < 0.002) than in Group I (98 +/- 10 ms). PTFV1 was greater in Group III (0.052 +/- 0.025 ms) than in Group I (0.028 +/- 0.011 ms, P < 0.05). P wave duration and PTFV1 had significantly and/or borderline correlations with longest duration of right atrial electrograms (r = 0.84, P < 0.0001 and 0.47, P < 0.02, respectively), maximal number of fragmented deflections of atrial electrograms (r = 0.69, P < 0.0001 and r = 0.51, P < 0.02, respectively), repetitive atrial firing zone (RAFZ) (r = 0.81, P < 0.0001 and 0.48, P < 0.05, respectively) and fragmented atrial activity zone (FAAZ)(r = 0.53, P < 0.01 and r = 0.45, P = 0.06, respectively). We concluded that long P wave duration and increased PTFV1 are electrocardiographic indicators for coexistence of electrophysiological abnormalities in the atria in SSS without recognizable heart disease.

Evaluation of electrocardiographic criteria for right atrial enlargement by quantitative two-dimensional echocardiography

OBJECTIVES

This study was conducted to evaluate the sensitivity and specificity of traditional electrocardiographic (ECG) criteria for right atrial enlargement and identify improve criteria, using quantitative two-dimensional echocardiography.

BACKGROUND

Traditional ECG criteria for right atrial enlargement, such as P pulmonale, have been increasingly criticized as insensitive and nonspecific. Quantitative two-dimensional echo-cardiography has been shown to be a useful method for evaluating atrial size.

METHODS

Hospitalized patients with mild, moderate and severe right atrial enlargement were selected from our laboratory's data base and compared with age- and gender-correlated hospitalized control subjects. After exclusions, 100 patients with right atrial enlargement and 25 control patients remained. Planimetric measurement of right atrial volumes was accomplished by two independent observers using the single-plane method of discs algorithm. Electrocardiograms were independently evaluated for current and newly proposed right atrial enlargement criteria.

RESULTS

Fifty-two patients (52%) were in sinus rhythm, 41 were in atrial fibrillation, 5 were in atrial flutter, and 2 were in ectopic atrial rhythm. All control subjects were in sinus rhythm. The right atrial volume for the control group was 35.0 +/- 7.4 ml (mean +/- SD), with a narrow, roughly normal distribution. The right atrial volume for the patient group was 147.6 +/- 69.1 ml (median 127.2) in a wide, skewed distribution. The difference of mean values was highly significant (p = 0.0001). Right ventricular enlargement was found to some degree in all patients with right atrial enlargement. The most powerful predictors of right atrial enlargement were a QRS axis > 90 degrees, a P wave height in lead V2 > 1.5 mm and an R/S ratio > 1 in lead V1 in the absence of complete right bundle branch block. The combined sensitivity of these three criteria was 49%, with preservation of 100% specificity. P pulmonale detected only 6% of patients with right atrial enlargement.

CONCLUSIONS

Using quantitative two-dimensional echocardiography, we found that most previously reported ECG criteria for right atrial enlargement have low predictive power. The best predictors of right atrial enlargement were a P wave height > 1.5 mm in lead V2 and, as new criteria, a QRS axis > 90 degrees and an R/S ratio > 1 in lead V1 in the absence of complete right bundle branch block. The combined sensitivity of these three criteria was 49%, with preservation of 100% specificity. Further studies are needed to prospectively validate these findings.

Diagnostic accuracy of the resting electrocardiogram in detection and estimation of left atrial enlargement: an echocardiographic correlation in 551 patients

The identification of LA enlargement may have important clinical implications. Previous correlations of ECG P wave morphologies associated with LA enlargement and echocardiography have been limited by the use of small numbers of patients and by the employment of M-mode echocardiography without the benefit of two-dimensional guidance. The purpose of this study was to further examine the sensitivity and specificity of various P wave morphologies (P wave greater than or equal to 110 msec, notched P greater than or equal to 40 msec, and PTFV1 greater than or equal to 40 msec.mm) for the diagnosis of LA enlargement and to determine if these waveforms may be predictive of LA size. ECGs and surface echocardiograms obtained within 1 week of each other were evaluated in 551 patients (140 normal and 411 study subjects). The various P wave morphologies were found to be poorly sensitive (30% to 60%) but very specific (90%) for LA enlargement. Combinations of P wave morphologies did not improve sensitivity or specificity. ECG features did give an estimate of the degree of LA enlargement. When PTFV1 is greater than or equal to 40 msec.mm, 95% of patients had LA size greater than or equal to 40 mm; and when this parameter was greater than or equal to 60 msec.mm, 75% had LA size greater than or equal to 60 mm. These criteria for LA enlargement on the ECG are specific and predictive of the degree of LA enlargement measured by echocardiography.

Electrocardiographic signs of atrial overload in hypertensive patients: indexes of abnormality of atrial morphology or function?

Left atrial electrocardiographic (ECG) abnormalities have been reported as common findings in hypertension; however, their relationships with atrial anatomy are still uncertain. In addition, in arterial hypertension several studies demonstrated an abnormal left ventricular filling. The aim of this study was to investigate the relationships of the ECG signs of left atrial abnormality to atrial anatomy and left ventricular filling as evaluated by pulsed-wave (PW) Doppler in a group of patients with uncomplicated essential hypertension. To this end, 53 untreated essential hypertensive patients (age 44 +/- 8 years; blood pressure 160.5 +/- 21.5/104.7 +/- 13.5 mm Hg) underwent a complete 12-lead ECG and a PW Doppler study of the transmitral flow velocities. The ECG criteria of left atrial abnormality were: P wave wider than 0.12 (or 0.10) second or higher than 0.25 mV in lead II; P wave/PR segment ratio (Macruz index) greater than 1.6 in lead II; and P wave terminal forces in lead V1 equal to or more negative than 0.04. Echocardiographic measurements were made according to American Society of Echocardiography (ASE) convention. Doppler parameters of left ventricular filling were measured as E and A peak velocity, A/E ratio, and the ratio between the velocity-time integral under the E peak and that of the whole diastolic flow, which represents the rapid filling fraction (RFF). At least one ECG sign of atrial abnormality was present in 34 patients (64%); the Macruz index gave the most common ECG index of atrial abnormality (31 patients).(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocardiographic diagnosis of left atrial enlargement. Role of the P terminal force in lead V1

The ability of the electrocardiographic criterion, P terminal force in lead V1 (PTF-V1), to diagnosis left atrial enlargement (LAE) is evaluated in a group of 317 men. A left atrial index greater than 2.2 cm/m2, determined by echocardiography, is used as the standard for LAE. The value for this criterion of 0.04 mm-sec performs best, although there is no significant difference in percent correct diagnosis for values of PTF-V1 ranging from 0.03 to 0.09 mm-sec.

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.

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.

The prognostic value of the P wave morphology in the discharge ECG in a 5-year follow-up study after myocardial infarction

The discharge ECG's of 641 patients with acute myocardial infarction (AMI) (WHO categories "definite" and "possible" AMI) were studied to assess the prognostic value of P wave morphology as an index of left ventricular dysfunction. Of 69 patients with abnormal P terminal force (PTF), i.e., --0.03 mm.sec. or more negative, 53.6 per cent died within the next 5 years of ischemic heart disease, compared with 20.4 per cent of 558 patients with normal PTF. The odds ratio (age-corrected risk to die, Mantel-Haenszel test) was 4.1 (95 per cent confidence limits 2.4 to 7.0). The mortality curve of patients with normal PTF was linear whereas there was an abrupt rise in mortality rate during the first six months if PTF was abnormal. Of a group of 15 patients with the frontal axis of the terminal P wave --30 degrees or more negative, 8 died (Odds ratio 4.7; 1.3 to 17.1). Ten patients had atrial fibrillation, and five of them died (Odds ratio 2.; 0.5 to 12.9). In 14 cases the duration of the P wave in Lead II was 0.12 sec. but it showed no relationship to mortality (p less than 0.10). The significance of the P wave morphology on the discharge ECG to long-term survival after MI has been demonstrated. These simple ECG variables, related to left ventricular failure, can easily be put to clinical use to differentiate MI patients who are in greater risk of dying during the chronic phase.

The vulnerability of the right atrium. III. Electrophysiologic correlates of atrial vulnerability

70 patients were investigated by means of the atrial extrastimulus method at three different driving rates: 80, 100 and 120/min. At each rate the effective, the relative, the total and the functional refractory periods were measured. 30 patients who showed signs of atrial vulnerability at least one of the tested rates were included in the so called vulnerability group. The remaining 40 patients, who did not fulfill the criteria for atrial vulnerability, were included in the nonvulnerability group. When the two groups were compared to each other there were significant larger P waves (p less than 0.005), shorter effective refractory periods (p less than 0.001) and longer relative refractory periods (p less than 0.001) in the vulnerability group. With increasing driving rate there was an increased tendency to repletitive firing in the vulnerability group. The phenomenon of vulnerability correlated well with the rate-induced shortening of the effective and the lengthening of the relative refractory period. The above described phenomena are compatible with the concept of re-entry as the electrophysiologic mechanism of atrial vulnerability in man.

Echocardiographic left atrial enlargement. Comparison of vectorcardiogram and electrocardiogram for detection

Standard electrocardiograms (ECG) and Frank vectorcardiograms (VCG) were obtained in 43 consecutive patients in sinus rhythm who had echocardiographic evidence of left atrial enlargement (left atrial internal dimension greater than 4.0 cm; x +/- 1SD = 4.7 +/- 0.5 cm). High gain VCG P loop measurements for the study group were: maximal posterior magnitude, 0.11 +/- 0.03 mv; duration, 106 +/- 14 msec and ratio of maximal posterior to maximal anterior P vector magnitudes, 3.2 +/- 1.4. Thirty of 43 (70%) patients with echocardiographic determined left atrial enlargement had VCGs diagnostic of that condition. Utilizing New York Heart Association criteria for left atrial enlargement, 17 of 43 patients (40%) had ECGs which were diagnostic. Fifteen of 43 (35%) subjects manifested both ECG and VCG criteria for left atrial enlargement and only two patients had diagnostic ECGs and normal VCGs. It is concluded that analysis of high gain VCG P loops provides a 30% higher yield for the diagnosis of echocardiographically determined left atrial enlargement when compared with P wave examination on the standard ECG.

The non-invasive recognition of left atrial enlargement: comparison of electro- and echocardiographic measurements

The aim of this study was to compare the ability of electro- and echocardiography to detect enlargement of the left atrium. Seventy-four patients, divided into three groups (eighteen normal, thirty-six valvular disease, twenty hypertension and/or coronary artery disease) were studied. The P wave terminal force in lead V1 (PTF-V1) was measured from a standard 12 lead electrocardiogram, and the internal left atrial dimension (LAD) was measured from time-motion echocardiograms. Linear regression analysis showed a small but significant linear correlation between PTF-V1 and LAD (r = 0-32, P less than 0-01). Both methods would separate patients with diseases known to cause left atrial enlargement from normals, but echocardiography showed greater "specificity" (100% v. 94+) and "sensitivity" (75% v. 67%). It was much superior to the ECG in detecting milder grades of left atrial enlargement and for following serial changes.

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.

Comparison of the electrocardiogram and vectorcardiogram for the diagnosis of left atrial enlargement

Standard 12 lead electrocardiograms (ECG) and Frank vectorcardiograms (VCG) were recorded in 21 consecutive patients with mitral valvular disease and angiographically documented left atrial enlargement. Comparative sensitivities for the detection of left atrial enlargement were: diagnostic, ECG = 6/21 (29%), VCG = 14/21 (67%); suggestive, ECG = 3/21 (14%), VCG = 2/21 (9%); non-diagnostic, ECG = 12/21 (57%), VCG = 5/21 (24%). It is concluded that the Frank atrial vectorcardiogram is superior to the standard electrocardiogram for the diagnosis of left atrial enlargement.

Electrocardiographic detection of left atrial enlargement. Correlation of P wave with left atrial dimension by echocardiography

The validity of various electrocardiographic P wave measurements was tested in 48 patients by comparing them to left atrial dimensions determined by echocardiography (echo), a proved method of left atrial size estimation. Of all the measurements considered, only the width of the P wave (PW), the P terminal force in lead V1 (PV1), and the PW/PR segment ratio (PW/PR) showed statistically significant correlations with left atrial size measurements by echo, with r values of 0-746, 0-491, and 0-479, respectively. The results indicated that P widths in excess of 105 ms were present in all the patients who had left atria equal to or greater than 3-8 cm by echo and in 11 per cent of patients without atrial enlargement (false positives), and that when measurements were less than 105 ms left atrial enlargement was unlikely.

Relationship between P wave form and left atrial pressure and volume in mitral valve disease

The P wave of the ECG, recorded with both conventional and special techniques, was compared with left atrial (LA) pressure and volume in 22 patients with mitral valve disease. The patients were also compared with 2 groups of normal subjects as to the P wave, recorded with the special technique. Changes in the P wave, such as increased duration, increased bipeak interval or P terminal force were significantly more common in the patients than in normal subjects. Among the patients, no significant correlations were found between degree of LA pressure elevation, LA enlargement and P wave changes. It is concluded that for the diagnosis of increased LA load it is more useful to study the terminal vector of the P wave than signs of increased atrial asynchrony. Recordings with high amplification and paper speed as in the present special technique are of advantage for such measurements. However, the special leads by themselves were not ideal for study of an increased terminal vector directed to the left and backwards.

P wave analysis in 2464 orthogonal electrocardiograms from normal subjects and patients with atrial overload

The purpose of this study was to establish limits of normal for P wave measurements, and to propose criteria for routine electrocardiographic readings and for multivariate analysis to recognize left atrial overload (LAO) and right atrial overload (RAO) in the orthogonal electrocardiogram (ECG). Frank ECG's were obtained from 2464 subjects, including 580 normals, 164 patients with mitral valve disease (MVD) forming the LAO group, and 623 with chronic lung disease (CLD) as the RAO sample. Each group was divided into training and test sets. Using a digital computer, 120 different P wave measurements were computed for each ECG to find optimal discriminators between normal (N), LAO, and RAO.

In the training set of MVD, using three scalar measurements, LAO was recognized in 57% with 3% false positives. These criteria diagnosed LAO in 70% of the test cases of MVD. Four discriminators identified RAO in 30% and 37% of training and test cases of CLD with 11% false positives.

A set of 15 measurements obtained by multivariate analysis was used in a classification in which the three groups, N, LAO, and RAO were considered simultaneously. Ninety-four percent N, 74% LAO, and 45% RAO in the training sets, and 95%, 71%, and 24% in N, LAO, and RAO test sets were correctly identified. An attempt was made to correlate the rate of recognition of LAO with the degree of LAO estimated by cardiac catheterization. Data reported in the present study can serve as standard for P wave analysis in the Frank ECG.

Prediction of left heart filling pressure and its sequential change in acute myocardial infarction from the terminal force of the P wave

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Value of serial P wave changes in indicating left heart failure in myocardial infarction

In order to evaluate ventricular failure in acute myocardial infarction, electrocardiographic left atrial overloading was correlated to several simultaneous clinical and radiological signs of left ventricular dysfunction in 200 consecutive patients. Analyses were made at three time periods after infarction. Left atrial overloading, measured by P terminal force, was significantly associated with the signs of left ventricular dysfunction, though in this unselected series of infarctions the prevalence of abnormal values was not high (46%). This finding is to be considered rather as a contributory sign than as a diagnostic one in the entire clinical picture. In an individual patient, however, conspicuous serial changes are helpful in indicating the direction of course of the haemodynamic disorder. The prognostic value of the P terminal force was found to be significant.