|
| HOME | SUBSCRIPTIONS | CURRENT ISSUE | PAST ISSUES | CARDIOSOURCE | SEARCH | HELP | FEEDBACK |
|
|
|
|||||||||
|
|||||||||||
|
J Am Coll Cardiol, 2002; 39:1443-1449 © 2002 by the American College of Cardiology Foundation |
,*
* Divisione di Cardiologia, Ospedale SS. Annunziata, Savigliano, Italy
Divisione di Cardiologia, Ospedale Mauriziano, Umberto I, Torino, Italy
Second Department of Medicine and Cardiology Center, Albert Szent-Györgyi Medical Faculty, University of Sciences, Szeged, Hungary
National Research Council, Consiglio Nazionale delle Ricerche, Institute of Clinical Physiology, Pisa, Italy
Manuscript received June 6, 2001; revised manuscript received January 31, 2002, accepted February 8, 2002.
* Reprint requests and correspondence: Dr. Eugenio Picano, Institute of Clinical Physiology, Pisa, CNR, Via Moruzzi, 1, 56100 Pisa, Italy.
picano{at}ifc.cnr.it
 |
Abstract |
|---|
 Top Abstract MethodsResultsDiscussionReferences |
|---|
BACKGROUND: Echocardiographic parameters for assessing long-term SR maintenance after successful CV of nonvalvular AF are not accurately defined.
METHODS: Clinical, transthoracic echocardiographic and transesophageal echocardiographic (TEE) data—measured in AF lasting >48 h—of 186 consecutive patients (116 men, mean age: 65 ± 9 years) with successful CV (electrical or pharmacologic) were analyzed for assessment of one-year maintenance of SR.
RESULTS: At one-year follow-up, 91 of 186 (49%) patients who underwent successful CV continued to have SR. Mean LAA peak emptying flow velocity was higher in patients remaining in SR for one year than in those with AF relapse (41.7 ± 20.2 cm/s vs. 27.7 ± 17.0 cm/s; p < 0.001). On multivariate logistic regression analysis, only the mean LAA peak emptying velocity >40 cm/s (p = 0.0001; 
2: 23.9, odds ratio [OR] = 5.2, confidence interval [CI] 95% = 2.7 to 10.1) and the use of preventive antiarrhythmic drug treatment (p = 0.0398; 2: 4.2; OR = 2.0, CI 95% = 1.0 to 3.8) predicted the continuous preservation of SR during one year, outperforming other univariate predictors such as absence of left atrial spontaneous echocardiographic contrast during TEE, the left atrial parasternal diameter <44 mm, left ventricular ejection fraction >46% and AF duration <1 week before CV. The negative and positive predictive values of the mean LAA peak emptying velocity >40 cm/s for assessing preservation of SR were 66% (CI 95% = 56.9 to 74.2) and 73% (CI 95% = 62.4 to 83.3), respectively.
CONCLUSIONS: In TEE-guided management of nonvalvular AF, high LAA flow velocity identifies patients with greater likelihood to remain in SR for one year after successful CV. Low LAA velocity is of limited value in identifying patients who will relapse into AF.
| ||||||||||||||||||||||||||
In recent years, transesophageal echocardiography (TEE) has emerged as an accepted tool to guide management of patients with AF by screening for left atrial appendage (LAA) thrombi and allowing earlier CV (5,6). Furthermore, the assessment of thrombembolic risk by measurement of LAA velocities during TEE in AF has become widely accepted (7–9). Recent studies have suggested that long-term SR maintenance may be predicted by evaluating LAA velocities before CV (10,11). However, this finding has been challenged by other reports (4), and the conclusions are weakened by the small sample size and heterogeneous patient population of the available studies. To clarify the long-term prognostic value of the LAA anterograde flow velocities, we evaluated, in a prospective, four-center, international study design, 193 consecutive patients with nonvalvular AF lasting <1 year in whom the SR was successfully restored by either electric or pharmacologic CV.
|
Methods |
|---|
|
TopAbstractMethodsResultsDiscussionReferences |
|---|
Echocardiography. Transthoracic echocardiography (TTE) and TEE were performed 24 h before the CV attempt with commercially available ultrasonographic systems (Hewlett-Packard Sonos 2500 and 5500, Acuson XP125 and Sequoia; ATL HDI 9, Andover, Massachusetts). The TEE was performed with bi- or multiplane probes with a 5- or 7-MHz transducer. The following TTE measurements were taken by parasternal long-axis view from two-dimensional targeted M-mode tracings according to the recommendations of the American Society of Echocardiography (12): LA diameter, LV end-diastolic and end-systolic diameter, LV septal and posterior end-diastolic wall thickness, ejection fraction (according to the Quinones formula). The two-dimensional biplane area-length method was used for ejection fraction calculation in patients with previous infarction. All TTE indices were measured off-line, using the integrated software of the echocardiographic equipment, and were calculated as the average of five consecutive cardiac cycles.
Following the TTE and after a 6-h fasting period, all patients underwent TEE examination. During the TEE, images were analyzed on-line by an experienced observer for the presence of intracardiac thrombus. To view the maximal size and to obtain the highest resolution of the LAA, the most appropriate section was always used for the analysis. The gain was continuously adjusted to ensure the best possible visualization and to avoid noise artifact. A thrombus was considered to be present when a well-circumscribed, echodense intracavitary mass that was acoustically distinct from the underlying endocardium was detected (13). Patients demonstrating intracardiac thrombus during TEE were excluded from the study.
Videotape and/or digitally stored images were subsequently analyzed off-line for the presence of LA spontaneous echocardiographic contrast and mitral valve regurgitation grade; this was done by two independent observers who were unaware of the patient’s history. Spontaneous echocardiographic contrast was defined as an intracavitary swirling smokelike echo within the left atrium or LAA (14). Mitral regurgitation was qualitatively graded by color flow Doppler mapping as none, mild, moderate or severe on the basis of regurgitant jet area and spatial distribution of the regurgitant flow (15). Differences between observers were resolved by consensus; if observers could not agree, a third and more experienced observer reviewed the study and his judgment was binding. The LAA velocity profiles were obtained by pulsed-wave Doppler interrogation 1 cm within the orifice of the LAA and analyzed off-line from videotape or digitally stored images by a single observer (A. P.), who was unaware of the patient’s history. The LAA peak emptying velocities were averaged with each RR-interval over a minimum of five consecutive cardiac cycles (16,17).
Follow-up. Patients were followed-up regularly every three months up to one year. Serial ECGs were recorded at each visit to document the maintenance of SR or recurrence of AF. In addition, referring physicians and patients were told to confirm suspected recurrences of AF by a 12-lead ECG. Initiation of preventive antiarrhythmic drug treatment during the follow-up was decided by the patient’s referring physician on the basis of integrated clinical assessment, which included access to echocardiographic data. According to this, 72 of the 193 (37%) successfully converted patients were treated by preventive antiarrhythmic drugs during the follow-up period. Drug therapy for arrhythmia prevention was flecainide (n = 9), amiodarone (n = 19), sotalol (n = 2) and propafenone (n = 42).
Statistical analysis. All data are expressed as means ± SD. In the intergroup comparison of clinical and echocardiographic continuous variables between patients with SR preservation compared to AF relapse, the statistical significance was assessed by the unpaired Student t test. Comparison of proportions was performed using chi-square analysis or the Fisher exact test as appropriate. Receiver-operating characteristic (ROC) analysis was used to determine optimal cutoff values of continuous variables for prediction of one-year SR preservation. The ROC curve represents the relationship between sensitivity and specificity, by plotting true-positive rate (sensitivity) against the false-positive rate (specificity), as the cutoff level of the model varies. The best cutoff value was defined as the point with the highest sum of sensitivity and specificity. The area under the ROC curve was used to quantify the ability of the mean LAA emptying velocity to predict the one-year SR maintenance accurately. Univariate and multivariate logistic regression models (toward forward stepwise procedure) were used to control for all possible confounding factors and to assess interaction between variables for assessment of one-year SR maintenance. The univariate and multivariate odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) are given. All tests were two-sided, and a p value <0.05 was considered statistically significant. All analyses were performed by an SPSS 9.0 software package (SPSS Inc., Chicago, Illinois).
|
Results |
|---|
|
TopAbstractMethodsResultsDiscussionReferences |
|---|
|
|
|
|
2 23.9, p < 0.0001) and the use of preventive antiarrhythmic drug during follow-up (OR = 2.0, CI 95% = 1.0 to 3.8; 2 4.2, p < 0.05) (Table 2). The diagnostic values of the different clinical and echocardiographic parameters are presented in Table 3.
|
|
|
Discussion |
|---|
|
TopAbstractMethodsResultsDiscussionReferences |
|---|
Comparison with previous studies. Previous studies have already demonstrated that the LAA velocity is related to the LA size (18,19) and the duration of AF (8,16), all of which are predictors of long-term SR maintenance. However, conflicting and scarce data exist on the usefulness of LAA flow to predict long-term preservation of SR (4,10,11). The discrepancy of the data can be easily reconciled by taking into account the limited sample size and variable inclusion criteria of the previous reports. Our study has distinct features: 1) the prospective, multicenter design, whereas all previous studies came from single-center experience; 2) the large number of patients enrolled (186 patients, whereas previous studies enrolled 38 to 75 patients); and 3) the strict selection criteria, which allowed us to exclude patients with valvular heart disease. The relatively large sample size enabled us to demonstrate that mean LAA peak emptying velocity has independent and additive prognostic value over other echocardiographic and clinical predictors, such as LA diameter, LA spontaneous echocardiographic contrast, ejection fraction and duration of AF whose prognostic value is totally eclipsed by LAA flow.
The possible link between LAA velocity and prediction of SR maintenance. In chronic nonvalvular AF, a time-related structural and histologic remodeling develops both in the LAA and in the left atrium (chamber dilation, loss of myofibrils, fragmentation of sarcoplasmatic reticulum and marked collagen formation) (20–25). These unfavorable degenerative changes may cause inhomogeneity of atrial repolarization, nonuniform anisotropy or slowing of conduction, and they are important components in the pathogenesis of AF (25,26). Loss of contractile elements of LAA may result in its reduced mechanical function, which could be expressed in low LAA flow velocities profile. However, according to our knowledge, there is no published data in the literature studying the direct link between LAA flow and histopathologic changes in the appendage in patients with nonvalvular AF.
Study limitations. The study population may appear heterogeneous with regard to the clinical parameters such as duration of AF, mode of CV, type of preventive antiarrhythmic therapy, but it corresponds to the variable clinical situations encountered in hospital practice. Therefore, the conclusions of this study can be reasonably applied to the general population of patients with nonvalvular AF of <1-year duration. It is important to note that the duration of follow-up influences the rate of preserved SR to some extent and may, therefore, affect the relationship between clinical parameters and outcome. Consequently, our conclusions are not necessarily valid for a longer follow-up period. Selection of patients for antiarrhythmic drug treatment may have introduced a potential bias that might have influenced the results to some extent. Nonetheless, the postcardioversion treatment was not randomized in our study the antiarrhythmic drug use were equally distributed in patients with high and low LAA flow.
Short, asymptomatic episodes of AF between the regular follow-up visits may have been missed in some patients, and this potential misclassification could have resulted in an underestimation of some difference.
The LAA areas were not assessed in our study; however, these measurements are inherently prone to substantial interobserver variability during both data registration and off-line analysis (8,27), possibly due to the complex three-dimensional anatomy of the LAA. In contrast, assessment of LAA function by Doppler echocardiography during TEE could be easily performed and it was reproducible and clinically highly relevant (7–9). The negative predictive value of LAA emptying flow velocity >40 cm/s for prediction of long-term SR preservation was relatively low, with a value of 66%. Thus, we do not know accurately whether a patient with low LAA flow velocity will relapse into AF within one year.
Conclusions. Our study showed that high LAA flow identifies those patients who will remain in SR for one year. Conversely, low LAA velocity is of limited value in identifying patients who will relapse into AF. In patients with nonvalvular AF, the same TEE-derived parameter often used to assess the embolic risk and to predict the chances of acute success of CV (28) (i.e., LAA flow) can be of use in predicting one-year outcome of successful CV.
|
Footnotes |
|---|
|
References |
|---|
|
TopAbstractMethodsResultsDiscussionReferences |
|---|
This article has been cited by other articles:
|
|
 |
|
  D. E. Singer, G. W. Albers, J. E. Dalen, M. C. Fang, A. S. Go, J. L. Halperin, G. Y. H. Lip, and W. J. Manning Antithrombotic Therapy in Atrial Fibrillation: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition) Chest, June 1, 2008; 133(6_suppl): 546S - 592S. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R I Dewar, G Y H Lip, and on behalf of the Guidelines Development Group for Identification, diagnosis and assessment of atrial fibrillation Heart, January 1, 2007; 93(1): 25 - 28. [Full Text] [PDF]
|
|
|
|
 |
|
 F. Holmqvist, M. Stridh, J. E.P. Waktare, L. Sornmo, S. B. Olsson, and C. J. Meurling Atrial fibrillatory rate and sinus rhythm maintenance in patients undergoing cardioversion of persistent atrial fibrillation Eur. Heart J., September 2, 2006; 27(18): 2201 - 2207. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Strandberg, M.J. P. Raatikainen, M. Niemela, M. Luotolahti, J. Hartiala, and K.E. J. Airaksinen Clinical practicality and predictive value of transoesophageal echocardiography in early cardioversion of atrial fibrillation Europace, June 1, 2006; 8(6): 408 - 412. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. D. Hoit Assessing Atrial Mechanical Remodeling and Its Consequences Circulation, July 19, 2005; 112(3): 304 - 306. [Full Text] [PDF]
|
|
|
|
|
|
M R M Jongbloed, M J Schalij, K Zeppenfeld, P V Oemrawsingh, E E van der Wall, and J J Bax Clinical applications of intracardiac echocardiography in interventional procedures Heart, July 1, 2005; 91(7): 981 - 990. [Full Text] [PDF]
|
|
|
|
|
|
T. R. Engel and S. K. Topalian The Pathology of Lone Atrial Fibrillation Chest, February 1, 2005; 127(2): 424 - 425. [Full Text] [PDF]
|
|
|
|
|
|
I. A. Paraskevaidis, T. Dodouras, D. Tsiapras, and D. T. Kremastinos Prediction of Successful Cardioversion and Maintenance of Sinus Rhythm in Patients With Lone Atrial Fibrillation Chest, February 1, 2005; 127(2): 488 - 494. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. E. Singer, G. W. Albers, J. E. Dalen, A. S. Go, J. L. Halperin, and W. J. Manning Antithrombotic Therapy in Atrial Fibrillation: The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy Chest, September 1, 2004; 126(3_suppl): 429S - 456S. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. L. McNamara, L. J. Tamariz, J. B. Segal, and E. B. Bass Management of Atrial Fibrillation: Review of the Evidence for the Role of Pharmacologic Therapy, Electrical Cardioversion, and Echocardiography Ann Intern Med, December 16, 2003; 139(12): 1018 - 1033. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | SUBSCRIPTIONS | CURRENT ISSUE | PAST ISSUES | CARDIOSOURCE | SEARCH | HELP | FEEDBACK |
