Axial correlates of PV1 in left atrial enlargement and relation to intraatrial block

Left Atrial Remodeling Assessed by Transthoracic Echocardiography Predicts Left Atrial Appendage Flow Velocity in Patients With Paroxysmal Atrial Fibrillation

Atrial fibrillation (AF) is associated with an increased risk of stroke and other thromboembolic events. Left atrial (LA) thrombus formation is closely related to LA dysfunction, particularly to decreased LA appendage flow velocity (LAA-FV) in patients with AF. We estimated LAA-FV using parameters noninvasively obtained by transthoracic echocardiography (TTE) in patients with paroxysmal AF.Echocardiographic and clinical parameters were assessed in 190 patients with nonvalvular paroxysmal AF showing sinus heart rhythm during transesophageal echocardiography (TEE) and TTE.LAA-FV (60 ± 22 cm/s) significantly correlated with the time interval between the initiation of the P-wave on ECG and that of the A-wave of transmitral flow on TTE (PA-TMF, correlation coefficient, -0.32; P < 0.001), LA dimension (LAD, -0.31; P < 0.001), septal a' velocity of tissue Doppler imaging (TDI, 0.35; P < 0.001), E/e' ratio (-0.28, P < 0.001), E velocity of transmitral flow (-0.20, P = 0.008), E/A ratio of transmitral flow (-0.18, P = 0.02), CHA2DS2-VASc score (-0.15, P = 0.04), and BNP plasma level (-0.32, P = 0.002). Multivariate analysis revealed that PA-TMF (standardized partial regression coefficient, -0.17; P = 0.03), a' velocity (0.24, P = 0.004), and LAD (-0.20, P = 0.01) were independent predictors of LAA-FV (multiple correlation coefficient R, 0.44; P < 0.001).Parameters of atrial remodeling, ie, decreased a' velocity, increased LAD, and PA-TMF during sinus rhythm may be useful predictors of LA blood stasis in patients with nonvalvular PAF. LAA-FV can be estimated using these TTE parameters instead of TEE.

Exceptional prevalence of interatrial block in a general hospital population

BACKGROUND

Interatrial block (IAB: P wave > or = 110 ms) is a strong correlate of left atrial (LA) enlargement and an important predictor of supraventricular tachyarrhythmias, notably atrial fibrillation and flutter. It is surprising that, despite its association with arrhythmias and its effects on the electromechanical properties of the left atrium, there is widespread neglect of this common abnormality.

HYPOTHESIS

The study was undertaken to investigate the prevalence of IAB in a general hospital population.

METHODS

We prospectively evaluated the electrocardiograms of 1,000 consecutive adult patients. analyzed for P-wave duration.

RESULTS

Our results showed a very high prevalence of IAB (41.1% of patients in sinus rhythm and 32.8% of all patients). As expected, it was more common in patients aged > 60 years.

CONCLUSIONS

Given this unusually high prevalence of IAB in hospital patients and its ominous portents (LA enlargement. thrombosis and embolism, arrhythmias), physicians should be aware of its frequency and computer software should be programmed to recognize it.

Optimal P-wave duration for bedside diagnosis of interatrial block

BACKGROUND

Interatrial block (IAB; P wave > or = 110 ms) is highly prevalent and associated with atrial tachyarrhythmias, left atrial electromechanical dysfunction and is a potential risk for embolism. Investigators have often used different parameters for P-wave duration to define IAB, and this causes confusion further adding to clinician ignorance of IAB. We therefore appraised the mode P-wave duration in IAB and evaluated the sensitivity and specificity of using previously used durations.

METHODS

We prospectively evaluated 225 electrocardiograms (ECGs) of patients at a tertiary care general hospital for P-wave duration. Of these, 49 were excluded because of severe motion artifact, errors in lead placement, absence of adequate patient identification, and atrial flutter or fibrillation. Mean, standard error of mean (SEM), standard deviation (SD), mode P-wave duration, specificity, and sensitivity were calculated of the remaining 176 ECGs.

RESULTS

From the sample (N = 176; ages 15-95 years; mean +/- SD = 69.15 +/- 16.53 years, female 50.3%), measured P-wave durations ranged from 50 ms to 230 ms (mean +/- SD = 113.75 +/- 30.56 ms, SEM 2.30 ms). 96 patients (54.55%) showed IAB (P wave > or = 110 ms) with the mode P-wave duration being 120 ms. Sensitivity and specificity of using P wave > or = 110 ms is 100% and 88.9%, respectively (accuracy 94.31%), while P wave > or =130 ms yielded 64% and 100%, respectively (accuracy 82.38%).

CONCLUSIONS

Mode P-wave duration in IAB is 120 ms, and thus, for all practical reasons, it may be used to clinically diagnose IAB using ECGs recorded at the bedside at 25 mm/s with 10 mm/mV standardization.

Widely split P waves in the presence of interatrial block

Interatrial block (IAB; P wave>or=110 milliseconds), conduction delay between the atria, is highly prevalent and is associated with atrial tachyarrhythmias, left atrial electromechanical dysfunction, as well as a potential risk for systemic embolism. However, much is still yet to be known of IAB's exact pathophysiology and how it may manifest in relation to medical disease. We present an unusual case of widely split P waves in the presence of IAB in a severely ill patient.

Interatrial block as a predictor of embolic stroke

Interatrial block (IAB), defined as a prolonged (>/=110 ms) P wave, is remarkably prevalent in general hospital populations and is associated with an enlarged, poorly contractile left atrium. The investigators sought to determine whether there is an increased incidence of IAB in patients with embolic strokes. Patients' medical records were reviewed for evidence of embolic cerebrovascular events and IAB. One hundred four patients were identified. In 61 patients in normal sinus rhythm, 49 (80%) had IAB. This was almost twice the prevalence of 2 previous studies (41% and 47%). Therefore, IAB may represent a new risk factor for stroke.

Electromechanical delay in the left atrium as a consequence of interatrial block

Right and left atrial electromechanical intervals and onsets of active right and left ventricular filling were measured in patients with interatrial block and compared with control patients. Left atrial mechanical activity is significantly delayed by interatrial block.