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

Electrocardiographic and Echocardiographic Predictors of Atrial Fibrillation in Patients With Hypertrophic Cardiomyopathy

Background

Patients with hypertrophic cardiomyopathy (HCM) have an increased prevalence of atrial fibrillation (AF) compared to the general population, and left atrium (LA) remodeling is strongly correlated with the risk of AF. This prospective, monocentric study aimed to assess the role of LA electrocardiographic and echocardiographic (structural and functional) parameters in predicting the risk for incident AF in patients with HCM.

Methods and Results

The study population consisted of 126 HCM patients in sinus rhythm (52.6 ± 16.2 years, 54 men), 118 of them without documented AF. During a median follow-up of 56 (7–124) months, 39 (30.9%) developed a new episode of AF. Multivariable analysis showed that LA booster pump function (assessed by ASr, HR = 4.24, CI = 1.84–9.75, and p = 0.038) and electrical dispersion (assessed by P wave dispersion – Pd, HR = 1.044, CI = 1.029–1.058, and p = 0.001), and not structural parameters (LA diameter, LA volume) were independent predictors of incident AF. Seventy-two patients had a LA diameter < 45 mm, and 16 of them (22.2%) had an AF episode during follow-up. In this subgroup, only Pd emerged as an independent predictor for incident AF (HR = 1.105, CI = 1.059–1.154, and p = 0.002), with good accuracy (AUC = 0.89).

Conclusion

Left atrium booster pump function (ASr) and electrical dispersion (Pd) are related to the risk of incident AF in HCM patients. These parameters can provide further stratification of the risk for AF in this setting, including in patients considered at lower risk for AF based on the conventional assessment of LA size.

P-Wave Terminal Force in Dogs With Myxomatous Mitral Valve Disease

P-wave terminal force (PTF) is accepted as an electrocardiographic criteria to assess left atrial abnormalities in humans. In this study, the applicability of PTF in dogs with myxomatous mitral valve disease (MMVD) was evaluated, and compared its ability to identify left atrial dilatation with 4 other P-wave derived parameters. Seventy-four dogs with echocardiographically diagnosed MMVD were recruited for this prospective cross-sectional study. Also, 47 healthy dogs were included to serve as controls. All dogs underwent physical, electrocardiographic and standard echocardiographic examinations prior to enrollment. Electrocardiographic measurements were obtained from simultaneous recordings at three different locations for precordial lead V₁. PTF was defined as the deflection following the second half of the P-wave, and was best documented at the first and third right intercostal spaces. In those locations, the P-wave was negative and P-wave terminal force was recognized as a positive undulation in baseline following P-wave. P-wave terminal force and P-wave duration measured from recordings obtained at either the first or third right intercostal spaces had poor to weak correlations (P < .05) with echocardiographic surrogates of cardiac remodeling and congestion. In dogs with MMVD, only P-wave duration and P-wave area distinguished normal and dilated left atria (P < .05). In conclusion, PTF had positive polarity and was best recorded when precordial lead V₁ electrode was placed at the most cranial right intercostal locations. PTF failed to reliably identify left atrial enlargement in dogs with MMVD.

Anxiety is associated with increased risk for atrial cardiopathy

Anxiety is common in patients with atrial fibrillation (AF). The mutual causal effect between anxiety and AF is expected with limited evidence. Atrial cardiopathy is a term to describe structural or electrophysiological atrium abnormality that precedes the onset of AF. This study aimed to investigate the association of anxiety with atrial cardiopathy, giving a clue to the causal relationship of this mind-heart link. This cross-sectional study analyzed 532 patients who were free of AF, atrial flutter, stroke, acute coronary syndrome and valvular heart disease. Atrial cardiopathy was defined as P-wave terminal force in lead V1 > 5000 μV·ms on electrocardiogram or severe left atrial enlargement on echocardiogram. Generalized anxiety disorder was ascertained by a score of > 17/56 on Hamilton anxiety rating scale. Multivariable logistic regression was used to explore the association of anxiety with atrial cardiopathy. A total of 65(12.2%) patients had atrial cardiopathy and 53(10.0%) had generalized anxiety disorder, respectively. Those with atrial cardiopathy were older (74.0 vs 67.0, P < 0.001), had a bigger left ventricular posterior wall thickness (10.1 vs 9.7 mm, P = 0.030), and had a higher prevalence of hypertension (83.1% vs 65.5%, P = 0.005), premature complexes (20.0% vs 6.2%, P < 0.001), and generalized anxiety disorder (20.0% vs 8.6%, P = 0.004), respectively. Multivariable logistic regression showed the significant association of anxiety with atrial cardiopathy (OR 2.788; 95% CI 1.304-5.960, P = 0.008), independent of confounding factors. Anxiety is independently associated with atrial cardiopathy. This association indicates the triggering effect of anxiety on atrial remodeling.

Assessment of electrocardiographic criteria of left atrial enlargement

Background Left atrial enlargement is considered to be a robust, strong, and widely acceptable indicator of cardiovascular outcomes. Echocardiography is the gold standard for measurement of left atrial size, but electrocardiography can be simple, cost-effective, and noninvasive in clinical practice. This study was undertaken to assess the diagnostic accuracy of an established electrocardiographic criterion for left atrial enlargement, taking 2-dimensional echocardiography as the gold-standard technique. Methods A cross-sectional study was conducted on 146 consecutively selected patients with the complaints of dyspnea and palpitation and with a murmur detected on clinical examination, from September 10, 2016 to February 10, 2017. Electrocardiography and echocardiography were performed in all patients. Patients with a negative P wave terminal force in lead V₁ > 40 ms·mm on electrocardiography or left atrial dimension > 40 mm on echocardiography were classified as having left atrial enlargement. Sensitivity and specificity were calculated to assess the diagnostic accuracy. Results Taking 2-dimensional echocardiography as the gold-standard technique, electrocardiography correctly diagnosed 68 patients as positive for left atrial enlargement and 12 as negative. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of electrocardiography for left atrial enlargement were 54.4%, 57.1%, 88.3%, 17.4%, and 54.8%, respectively. Conclusion The electrocardiogram appears to be a reasonable indicator of left atrial enlargement. In case of nonavailability of echocardiography, electrocardiography can be used for diagnosis of left atrial enlargement.

P-wave morphology is unaffected by atrial size: a study in healthy athletes

BACKGROUND

Orthogonal P-wave morphology has previously been described in different populations, but its relation to atrial size has not been studied in detail. In this study, we investigated whether atrial size affects P-wave morphology in athletes, who are known to have different degrees of atrial enlargement.

METHODS

A total of 504 healthy, male, professional soccer players were included (median age 25 years). All underwent echocardiographic and 12-lead electrocardiographic (ECG) recordings. The ECG was transformed into orthogonal leads, using the inverse Dower transform. The association between echocardiographic parameters and standard P-wave measures (i.e., orthogonal morphology, left atrial abnormality assessed as negative P-wave terminal force [PTF] in lead V1 > 0.04 mm × s, and duration) was analyzed.

RESULTS

The vast majority had either type 1 P-wave morphology (75%) (positive leads X and Y and negative lead Z) or type 2 P-wave morphology (22%) (positive leads X and Y and biphasic lead Z [negative/positive]). Left atrial enlargement (≥29 mL/m(2) ) was found in 79% on echocardiography. There was no significant difference in left atrial end-systolic volume, left or right atrial diameters, or right atrial area between individuals with different P-wave morphologies. ECG signs of left atrial abnormality were found in eight subjects, who did not have significantly larger left atrial dimensions than the rest.

CONCLUSIONS

We demonstrated that P-wave morphology does not depend on the size of the atria in young, healthy athletes, and that PTF is not a reliable marker of left atrial enlargement in the current population.

Usefulness of electrocardiographic parameters as compared with computed tomography measures of left atrial volume enlargement: from the ROMICAT trial

INTRODUCTION

The 12-lead surface electrocardiogram (ECG) is commonly used as a noninvasive modality to assess for left atrial enlargement (LAE), but data comparing ECG against cardiac computed tomography (CT) for LAE is lacking. We aimed to determine the diagnostic performance of 6 ECG criteria for LAE as compared with CT left atrial volume (LAV) and index to body surface area (LAVI) as the reference standard.

MATERIALS AND METHODS

In 339 patients (age: mean ± mean, 53 ± 12 years; 63% male), we evaluated the quantitative ECG parameters of P duration, P to PR segment ratio, P wave area, and P terminal force in lead V1. We also assessed qualitatively the morphology of bifid and biphasic P waves. Patients were stratified into top and lowest quartile of LAV and LAVI by CT.

RESULTS

Of the 6 ECG criteria, patients with P duration greater than 110 milliseconds had a 2½-fold increase likelihood of being in the top quartile of LAV (adjusted odds ratio [OR], 2.51; P = .01) and LAVI (adjusted OR, 2.74; P = .007) as measured by CT. For this ECG criterion, the sensitivity and specificity were 71% and 55% for CT LAE by LAV and 61% and 55% for LAVI. The remaining ECG parameters of LAE assessed (P to PR segment ratio, P terminal force in lead V1, P wave area, bifid, and biphasic P wave) were not associated with LAE by CT-based LAV or LAVI (all P ≥ .20).

DISCUSSION

Only P duration greater than 110 milliseconds was independently associated with LAE based on CT-derived LA volume and index. However, none of the established ECG parameters of LAE have sufficient diagnostic accuracies for predicting volumetric enlargement by CT, thus limiting its clinical utility.

Abnormal P-wave morphology is a predictor of atrial fibrillation development and cardiac death in MADIT II patients

BACKGROUND

Several ECG-based approaches have been shown to add value when risk-stratifying patients with congestive heart failure, but little attention has been paid to the prognostic value of abnormal atrial depolarization in this context. The aim of this study was to noninvasively analyze the atrial depolarization phase to identify markers associated with increased risk of mortality, deterioration of heart failure, and development of atrial fibrillation (AF) in a high-risk population with advanced congestive heart failure and a history of acute myocardial infarction.

METHODS

Patients included in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) with sinus rhythm at baseline were studied (n = 802). Unfiltered and band-pass filtered signal-averaged P waves were analyzed to determine orthogonal P-wave morphology (prespecified types 1, 2, and 3/atypical), P-wave duration, and RMS20. The association between P-wave parameters and data on the clinical course and cardiac events during a mean follow-up of 20 months was analyzed.

RESULTS

P-wave duration was 139 + or - 23 ms and the RMS20 was 1.9 + or - 1.1 microV. None of these parameters was significantly associated with poor cardiac outcome or AF development. After adjustment for clinical covariates, abnormal P-wave morphology was found to be independently predictive of nonsudden cardiac death (HR 2.66; 95% CI 1.41-5.04, P = 0.0027) and AF development (HR 1.75; 95% CI 1.10-2.79, P = 0.019).

CONCLUSION

Abnormalities in P-wave morphology recorded from orthogonal leads in surface ECG are independently predictive of increased risk of nonsudden cardiac death and AF development in MADIT II patients.

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.

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.

Atrial gradient as a potential predictor of atrial fibrillation

OBJECTIVES

We tested the utility and comparability of the atrial gradient and atrial ERP as early markers of electrical remodeling and a propensity to atrial fibrillation (AF).

BACKGROUND

Pacing at physiologic rates from the left atrium alters the atrial gradient and is associated with atrial tachyarrhythmias. At these physiologic rates, there is no change in the atrial effective refractory period (ERP).

METHODS

Sixty-one chronically instrumented mongrel dogs in complete heart block were paced from the left or right atrium at 400 to 900 bpm for 46 +/- 3 days. Dogs were monitored weekly and electrophysiologic studies conducted to determine changes in the atrial gradient, ERP, and rhythm.

RESULTS

Rapid atrial pacing was associated with concordant decreases in atrial gradient, ERP, and occurrence of AF. Incidence of AF increased with increasing pacing rate. Although there ultimately was an equal incidence of AF with left atrial and right atrial pacing, the onset of AF occurred earlier with left atrial pacing. As expected, ERP decreased in both atria. Animals with long control ERP did not fibrillate.

CONCLUSIONS

Rapid pacing induces changes in atrial gradient, which can be used as a noninvasive marker of electrical remodeling. AF is accompanied by decreases in atrial gradient and ERP, and the incidence is highest in dogs with short control ERP.

Detection of patients with hypertrophic cardiomyopathy at risk for paroxysmal atrial fibrillation during sinus rhythm by P-wave dispersion

BACKGROUND

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 - Pmin) 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.

Effects of P-wave dispersion on atrial fibrillation in patients with acute anterior wall myocardial infarction

BACKGROUND

P-wave dispersion (P dispersion), defined as the difference between the maximum and the minimum P-wave duration (P minimum), and maximum P-wave duration (P maximum) have been used to evaluate the discontinuous propagation of sinus impulse and the prolongation of atrial conduction time respectively. The aim of this study was to investigate whether early assessment of P dispersion predicts paroxysmal atrial fibrillation (AF) in patients with acute anterior wall myocardial infarction (MI).

METHODS

We prospectively evaluated 147 consecutive patients (45 women, 102 men; aged 55 +/- 9 years) with a first acute anterior wall MI. All patients were evaluated by echocardiography to measure the left atrial diameter and left ventricular ejection fraction (LVEF). Electrocardiography was recorded from all patients on admission and every day during hospitalization.

RESULTS

AF occurred in 25 patients. In 122 patients, AF did not occur. P maximum was found to be significantly higher in patients with AF than in patients without AF (115 +/- 17.3 ms vs 101 +/- 14.7 ms, P = 0.001). P dispersion also was significantly higher in patients with AF than in patients without AF (50 +/- 12.5 ms vs 43 +/- 10.1 ms, P = 0.01). There was no significant difference between the two groups in P minimum (64 +/- 12.5 ms vs 59 +/- 11.7 ms, P = 0.057). The echocardiographically left atrial diameters were not significantly higher in the patients with AF than those without (25 +/- 3.38 mm and 23 +/- 3.36 mm, respectively, P = 0.76). LVEF was found to be significantly different in the patients who developed AF and in those who did not (37.96 +/- 6.18% vs 47.70 +/- 6.01%, P = 0.0001).

CONCLUSIONS

Although P maximum and P dispersion are significant predictive factors of AF in patients with acute anterior wall MI in the univariate analysis, on the basis of multivariate analysis, only age and LVEF were independent predictive parameters for AF.

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.

F-amplitude, left atrial appendage velocity, and thromboembolic risk in nonrheumatic atrial fibrillation. Stroke Prevention in Atrial Fibrillation Investigators

BACKGROUND

Reduced left atrial appendage velocity (LAAV) has been identified as a marker for thromboembolism in patients with atrial fibrillation.

HYPOTHESIS

It was postulated that electrocardiographic (ECG) F-wave amplitude would correlate with LAAV, and inversely with the risk of thromboembolism in patients with atrial fibrillation.

METHODS

In all, 53 patients with nonrheumatic (NRAF) and 7 patients with rheumatic (RAF) atrial fibrillation underwent assessment of maximum LAAV, which was correlated to the maximum ECG F-wave voltage from lead V1 (F(max)). In 450 NRAF patients on neither aspirin nor warfarin, the relationship between F(max) and thromboembolic risk was assessed over an average follow-up of 1.3 years.

RESULTS

F(max) did not correlate with LAAV (r = 0.2, p = 0.07). Patients with intermittent atrial fibrillation (n = 123) had smaller F(max) amplitude than patients with constant atrial fibrillation (n = 327) (mean 0.73 vs. 0.88 mV-1, p = 0.001). F(max) amplitude was not related to a history of hypertension, systolic blood pressure, duration of NRAF, abnormal transthoracic echocardiographic left ventricular (LV) systolic function or left atrial (LA) diameter. There was a strong trend for increased LV mass being related to smaller F(max) amplitude after adjusting for body surface area (p = 0.06). F(max) amplitude was not correlated with risk of embolic events, including only those events presumed by a panel of case-blinded neurologists to be cardioembolic.

CONCLUSIONS

F(max) amplitude in NRAF is smaller in patients with intermittent versus constant AF. It does not correlate with LAAV, LA size, increased LV mass, or systolic dysfunction, hypertension, or risk of embolism. Therefore, F(max) amplitude may not be used as a surrogate for LAAV, or as a measure of thromboembolic risk in NRAF.

Predictive value of the P wave at implantation for atrial fibrillation after VVI pacemaker implantation

This study assesses the value of P wave measurements on the surface ECG at implantation, in the prediction of atrial fibrillation in VVI paced patients. From a consecutive series of 320 pacemaker implantations 172 VVI paced patients for symptomatic atrioventricular block (AVB) (n = 126; mean age 69 +/- 14) or sick sinus syndrome (SSS) (n = 56; mean age 68.6 +/- 12) and in sinus rhythm at implantation were used in this study. P wave duration in V1 is correlated with the incidence of atrial fibrillation during 5 years of follow-up. V1 at implantation was significantly longer (114.6 +/- 2.7 msec) in the patients who developed atrial fibrillation than in those who did not (91.9 +/- 2.7 msec) (P < 0.001). Although positive predictive accuracy increases progressively for higher V1 values for AVB and SSS, the negative predictive and diagnostic accuracy of V1 criteria were less in SSS. Application of the Bayes' theorem showed that in SSS the probability to develop atrial fibrillation is 33% for V1 < 110 msec and is for V1 < 90 msec still higher than that reported in DDD paced patients. In the AVB group the probability to develop atrial fibrillation is 8% for V1 < 110 msec and 6% for V1 < 100 msec. It seems, therefore, that atrial stimulation (AAI or DDD) is always indicated in SSS. In AVB with V1 < 100 msec, DDD pacing, if not needed for other indications, apparently does not offer much benefit in the prophylaxis of atrial fibrillation.

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)

Evolution of P wave characteristics after pacemaker implantation

This study is an investigation of the long-term effects of VVI pacing on the atrium as derived from the evolution of P wave characteristics of 285 patients. The occurrence of left and right atrial disease is demonstrated as well as the evolution of left atrial hypertrophy in some cases. A comparison is made with DDD pacing and special attention is given to the progression to atrial fibrillation.