[Nonpharmacological methods of prevention of thromboembolic complications in patients with atrial fibrillation]

We present in this review modern methods of prevention of thromboembolic complications in patients with atrial fibrillation and give comparative description of evidence base, efficacy and safety of available techniques.

Differential gene expression during atrial structural remodeling in human left and right atrial appendages in atrial fibrillation

Extracellular matrix (ECM) remodeling increases the vulnerability to atrial fibrillation (AF). Some gene expressions are crucial for the metabolism of ECM. The left atrium plays an important role in maintaining AF. However, most studies investigated only the right atrial tissue. We therefore chose human tissue samples from both the left and right atrial to detect the different gene expressions during structural remodeling in AF. The atrial appendages tissue samples from 24 patients with chronic AF and 12 patients with sinus rhythm were obtained when they were undergoing mitral/aortic valve replacement operation. The mRNA levels of matrix metalloproteinases-9 (MMP-9), tissue inhibitor of metalloproteinase-1 (TIMP-1), disintegrin, metalloproteases-15, and integrins β1 were determined by reverse transcription-polymerase chain reaction (RT-PCR). In AF group, the level of MMP-9 in left atrial appendage (LAA) was increased (P< 0.001), while integrin β1 level was decreased (P< 0.05) compared with those expressed in right atrial appendage (RAA) tissue. The levels of disintegrin, metalloproteinases-15, and TIMP-1 genes in the LAA and RAA had no significant differences. The results demonstrated that the gene expressions in the LAA and RAA are different during AF, which implied that the mechanism of atrial structural remodeling in AF is due to multiple sources and is complicated.

Left atrial appendage function in mitral stenosis: is it determined by cardiac rhythm?

BACKGROUND AND AIM OF THE STUDY

The left atrial appendage (LAA) is a common source of cardiac thrombus formation associated with systemic embolism in patients with mitral stenosis (MS). Low flow velocities in the LAA are important factors in the development of thrombosis. Whilst oral anticoagulant therapy is used routinely in MS with atrial fibrillation (AF), the characteristics of LAA contractile functions and the protective role of oral anticoagulant treatment in patients with MS in sinus rhythm (SR) are unclear. The study aim was to compare LAA contractile functions in patients with MS who were either in SR or had AF.

METHODS

The study population comprised 51 patients with MS, who had undergone both standard transthoracic and transesophageal echocardiography. The patients were allocated to two groups, according to the presence of AF or SR. Ten healthy, gender-matched subjects were included in the study as a control group.

RESULTS

Except for age, the characteristics of the groups were similar. In patients with SR and AF, the LAA contractile functions were significantly lower than in controls. While the LAA contractile functions of the SR group were significantly lower than the AF group (LAA emptying/filling velocity: 26 +/- 7/24 +/- 8 versus 19 +/- 5/17 +/- 5 cm/s; p = 0.002 and p = 0.001, respectively, LAA maximum/minimum area: 5.4 +/- 1.2/3.2 +/- 0.9 versus 6.2 +/- 1.1/3.7 +/- 0.8 cm2, p = 0.02 and p =0.02, respectively), no statistically significant differences were observed between patients in SR with mitral valve area (MVA) <1.5 cm2 and patients in AF. Four SR patients (13%) and six AF patients (27%) had LAA thrombus. A strong correlation was observed between the MVA and LAA peak emptying/filling velocity in patients with MS in SR (r = 0.739, p = 0.0001 and r = 0.728, p = 0.0001, respectively).

CONCLUSION

The study results showed that LAA contractile function is diminished in patients with moderate-severe MS in SR, and to a similar degree as patients in AF. It was concluded that patients with moderate-severe MS in SR have a higher risk for thromboembolic events than MS patients in AF.

[Electrophysiological characterization and efficacy of radiofrequency ablation of focal atrial tachycardia originating from the left atrial appendage]

OBJECTIVE

To analyze the electrophysiological characteristics and efficacy of radiofrequency catheter ablation (RFA) of focal atrial tachycardia (AT) originating from the left atrial appendage (LAA).

METHODS

Electrophysiologic study and RFA were performed in 9 patients (4 female) with focal AT originating from the LAA. Atrial appendage angiography was performed to identify the origin of AT. P waves were classified as negative, positive, isoelectric, or biphasic.

RESULTS

The mean age was (21 +/- 9) years. AT occurred spontaneously or was induced by isoproterenol infusion rather than programmed extrastimulation and burst atrial pacing. A characteristic P-wave morphology and endocardial activation pattern were observed. Positive P-wave in inferior leads was seen in all patients, upright or biphasic (+/-) component P wave was observed in lead V1, isoelectric component or an upright component P wave with low amplitude ( < 0.1 mV) was seen in lead V2-V6. Earliest endocardial activity occurred at the distal coronary sinus (CS) in all patients. The earliest endocardial activation at the successful RFA site occurred (36.7 +/- 7.9) ms before the onset of P wave. RFA was successful in all 9 patients immediately post procedure. AT reoccurred in 2 patients within 1 month post RFA and AT disappeared post the 2nd-RFA. AT reoccurred in 1 patient and terminated after the 3rd RFA. At the final follow-up (12 +/ 5) months, all 9 patients were free of arrhythmias without antiarrhythmic drugs.

CONCLUSIONS

The LAA is an uncommon site of origin for focal AT. The characteristic P wave and activation timing are suggestive for focal AT originating from the LAA. LAA focal ablation is safe and effective for patients with focal AT originating from the LAA.

[Predictors of occurrence of left atrium and left appendage thrombosis in patients with nonvalvular atrial fibrillation]

OBJECTIVE

To determine the predictors of thrombosis in left atrium (LA) or left atrial appendage (LAA) in patients with nonvalvular atrial fibrillation.

METHODS

Two hundred and eight patients under 65 year old with atrial fibrillation (AF) were included and all of them received examination of transesophageal echocardiography (TEE). Thrombus formation in LA/LAA was found in 23 patients (thrombus group) but absent in the remaining 185 patients (nonthrombus group). All patients were analyzed by univariate regression and binary logistic regression to investigate the relationship between the occurrence of LA/LAA thrombosis and these factors (such as case history, smoking/drinking preference, indicators of clinical blood examination and ultrasound imaging study, etc)

RESULTS

Univariate analysis revealed that diameter of LA [(34.9 +/- 4.4) mm vs (42.2 +/- 6.5) mm, P = 0.000], ratio of chest and heart (60/185 vs 20/23 P = 0.000), brain infarction/transient ischemic attack (TAI) (7/185 vs 6/23 P = 0.000), smoking (30/185 vs 8/23, P = 0.030), fibrinogen (FIB) [(3.0 +/- 0.7)g/L vs (3.5 +/- 1.0) g/L, P = 0.000], coronary artery disease (CAD) (10/185 vs 6/23, P = 0.000) and LVDd [(45.7 +/- 4.1) mm vs (48.5 +/- 5.7) mm, P = 0.000] and LVEF [(65.1 +/- 6.6) mm vs (59.3 +/- 1.3) mm, P = 0.050] were significant between nonthrombus group and thrombus group (P < 0.05). However binary logistic regression analysis identified that only LAD, ratio of chest and heart, brain infarction/TAI and FIB were the significant and independent predictors of LA/LAA thrombosis.

CONCLUSION

Diameter of LA, ratio of chest and heart, brain infarction/TAI and FIB are independent risk factors of thrombosis in patients under 65 year old with nonvalvular atrial fibrillation. These patients need a better anticoagulation.

Percutaneous closure of the left atrial appendage versus warfarin therapy for prevention of stroke in patients with atrial fibrillation: a randomised non-inferiority trial

BACKGROUND

In patients with non-valvular atrial fibrillation, embolic stroke is thought to be associated with left atrial appendage (LAA) thrombi. We assessed the efficacy and safety of percutaneous closure of the LAA for prevention of stroke compared with warfarin treatment in patients with atrial fibrillation.

METHODS

Adult patients with non-valvular atrial fibrillation were eligible for inclusion in this multicentre, randomised non-inferiority trial if they had at least one of the following: previous stroke or transient ischaemic attack, congestive heart failure, diabetes, hypertension, or were 75 years or older. 707 eligible patients were randomly assigned in a 2:1 ratio by computer-generated randomisation sequence to percutaneous closure of the LAA and subsequent discontinuation of warfarin (intervention; n=463) or to warfarin treatment with a target international normalised ratio between 2.0 and 3.0 (control; n=244). Efficacy was assessed by a primary composite endpoint of stroke, cardiovascular death, and systemic embolism. We selected a one-sided probability criterion of non-inferiority for the intervention of at least 97.5%, by use of a two-fold non-inferiority margin. Serious adverse events that constituted the primary endpoint for safety included major bleeding, pericardial effusion, and device embolisation. Analysis was by intention to treat. This study is registered with Clinicaltrials.gov, number NCT00129545.

FINDINGS

At 1065 patient-years of follow-up, the primary efficacy event rate was 3.0 per 100 patient-years (95% credible interval [CrI] 1.9-4.5) in the intervention group and 4.9 per 100 patient-years (2.8-7.1) in the control group (rate ratio [RR] 0.62, 95% CrI 0.35-1.25). The probability of non-inferiority of the intervention was more than 99.9%. Primary safety events were more frequent in the intervention group than in the control group (7.4 per 100 patient-years, 95% CrI 5.5-9.7, vs 4.4 per 100 patient-years, 95% CrI 2.5-6.7; RR 1.69, 1.01-3.19).

INTERPRETATION

The efficacy of percutaneous closure of the LAA with this device was non-inferior to that of warfarin therapy. Although there was a higher rate of adverse safety events in the intervention group than in the control group, events in the intervention group were mainly a result of periprocedural complications. Closure of the LAA might provide an alternative strategy to chronic warfarin therapy for stroke prophylaxis in patients with non-valvular atrial fibrillation.

FUNDING

Atritech.

Focal atrial tachycardia arising from the right atrial appendage: electrophysiologic and electrocardiographic characteristics and catheter ablation

BACKGROUND

Focal atrial tachycardia (AT) arising from the crista terminalis, pulmonary veins, para-Hisian region, tricuspid annulus and coronary sinus ostium regions are well described. Less information exists regarding AT arising from the right atrial appendage (RAA).

OBJECTIVE

The study was done to characterise the electrocardiographic and electrophysiologic features and radiofrequency ablation (RFA) of focal AT arising from the RAA.

METHODS

Six patients of a consecutive series of 250 patients undergoing RFA for focal AT are reported. Mapping was performed during tachycardia or frequent atrial ectopy to identify the earliest activation in the atria. Atrial appendage angiography was performed to identify the origin in the RAA after RFA.

RESULTS

All the six (2.4%) patients (four women; mean age 26 +/- 11 years) had tachycardia originating from RAA. The tachycardia demonstrated a characteristic P-wave morphology and endocardial activation pattern. P-wave morphology was upright in I, II, III and aVF, inverted in aVR, inverted or isoelectric in aVL. Lead V1 showed a negative component and lead V4-V6 showed an upright component in all the patients. The earliest endocardial activity occurred at the high right atria in all the patients. The earliest endocardial activation at the successful RFA site occurred 48 +/- 18 ms before the onset of the P wave. RFA was highly successful in all the six patients. Long-term success was achieved in six of the six patients over a mean follow-up of 24 +/- 5 months.

CONCLUSIONS

The RAA is an uncommon site of origin for focal AT 2.4%. There is consistent P-wave morphology and endocardial activation associated with this type of AT. Using mapping targeted to anatomic structures achieved a high success rate for ablation. Irrigated-tip catheter may be helpful for patients who had a recurrence.

Influence of age on left atrial appendage function in patients with nonvalvular atrial fibrillation

BACKGROUND

Age is an independent risk factor for thromboembolism in nonvalvular atrial fibrillation (NVAF). An association between low left atrial appendage (LAA) Doppler velocities and thromboembolic risk in NVAF has been reported.

HYPOTHESIS

The study was undertaken to identify age-related differences in LAA function that may explain the higher thromboembolic rates in older patients with NVAF.

METHODS

Forty-two consecutive patients (age 69+/-2 years [range 42-92], 24 [57%] men) with NVAF underwent transthoracic and transesophageal echocardiography. The following were compared in 22 patients younger and 20 older than 70 years: left ventricular (LV) diameter, mass and ejection fraction, left atrial (LA) diameter and volume, LAA area and volume, LAA peak emptying (PE) and peak filling (PF) velocities, presence and severity of spontaneous echo contrast (SEC) and mitral regurgitation (MR).

RESULTS

Left atrial diameter (4.6+/-0.1 vs. 4.5+/-0.2 cm), LA volume (105+/-10 vs. 92+/-8 ml), LAA area (6.8+/-0.6 vs. 5.2+/-0.8 cm2), and LAA volume (5.6+/-0.9 vs. 3.9+/-1.0 ml) were similar (p>0.05) in both groups. Older patients had lower LAA PE (26+/-2 vs. 34+/-3 cm/s, p = 0.02) and PF (32+/-2 vs. 41+/-4 cm/s, p = 0.04) velocities, lower LV mass (175+/-13 vs. 234+/-21 gm, p = 0.02), higher relative wall thickness (0.52+/-0.02 vs. 0.43+/-0.03, p = 0.02), smaller LV diastolic diameter (4.3+/-0.1 vs. 5.2+/-0.2 cm, p < 0.001), and higher LV ejection fraction (62+/-2 vs. 55+/-2%, p = 0.025). Frequency and severity of SEC and MR were similar in both groups. Multivariate analysis identified older age as the only significant predictor of reduced LAA velocities.

CONCLUSION

Compared with younger patients, older patients with NVAF have lower LAA velocities despite higher LV ejection fraction, smaller LV size, and similar LA and LAA volumes. These findings may explain the higher thromboembolic rates in older patients with NVAF.

Usefulness of intensity variation in the left atrial appendage with contrast echocardiography to predict ischemic stroke recurrence in patients with atrial fibrillation

The left atrial appendage (LAA) is 1 of the common thromboembolic sources in patients with atrial fibrillation (AF) with stroke. The aim of this study was to examine the usefulness of LAA opacification seen on contrast echocardiography for predicting stroke recurrence in patients with AF. In 192 patients with stroke with AF who underwent transesophageal echocardiography within 7 days after the onset, intracardiac intensity variation at the orifice of the LAA just after intravenous infusion of Levovist (1,500 mg) was measured. During a mean follow-up of 450 days, the association between LAA intensity variation and recurrence of cerebrovascular events was assessed. LAA intensity variation was markedly lower in 19 patients with stroke recurrence than 173 patients without stroke recurrence (8.1 +/- 4.7 vs 12.1 +/- 5.1 dB; p <0.001). LAA thrombus-negative patients with low LAA intensity variation (< or =9.2 dB; n = 45) had higher cerebrovascular recurrent event rates than those with high LAA intensity variation (>9.2 dB; n = 109; 20.0% vs 3.7%; p <0.001) and thrombus-positive patients (15.8%). Cox multivariate hazard analysis showed that of routine echocardiographic parameters, decreased LAA intensity variation was the only independent predictor of stroke recurrence (hazard ratio 5.244, p <0.01). In conclusion, LAA intensity variation on contrast transesophageal echocardiography is a new sensitive index for LAA flow stagnation and recurrent cerebrovascular events in patients with AF with stroke.

Mitral valve replacement impairs the flow in the left atrial appendage in mitral regurgitation

OBJECTIVE

We aimed to assess the left atrial appendage (LAA) flow velocities of rheumatic valves in 46 patients, diagnosed with isolated mitral regurgitation (MR) (16 patients), mitral stenosis (MS) (14 patients) and combined MS and MR (MS + MR) (16 patients) before and after operation.

METHODS

The patients were subdivided into two groups, according to rhythm: sinus (SR) (20 patients) and atrial fibrillation (AF) (26 patients). All patients underwent transthoracic and transoesophageal echocardiography before and after the operation.

RESULTS

Preoperatively LAA flow velocities were the best in the MR group among the three groups. Postoperatively there was no statistically significant difference between the MR group and the other two groups for mean peak emptying and filling velocities in patients with SR and AF. The incidence of spontaneous echo contrast (SEC) and thrombus significantly increased in the MR group after operation. Thrombus was only seen in patients with AF at the postoperative period.

CONCLUSIONS

Mitral valve replacement disturbs LAA flow velocities and increases the risk of thrombus formation in patients with MR. This risk was more obvious in cases with AF. Impaired left atrial appendage flow velocities increase the risk of thrombus formation. We recommend close follow-up for the increased possibility of thrombus formation in patients who had MR preoperatively and AF postoperatively.

Electrophysiologic and electrocardiographic characteristics and radiofrequency catheter ablation of focal atrial tachycardia originating from the left atrial appendage

BACKGROUND

The left atrial appendage (LAA) is one of the major sources of focal atrial tachycardias (ATs).

OBJECTIVE

The purpose of this study was to investigate the detailed electrophysiologic characteristics and catheter ablation of focal ATs originating from the LAA.

METHODS

The study population consisted of 47 consecutive patients with 50 focal ATs originating from the left atrium (LA): LAA in 13, left pulmonary veins (PVs) in 14, right PVs in 12, and mitral annulus in 11. Programmed electrical stimulation and pharmacologic testing were performed to examine the mechanism of LAA AT. Left atriography was performed prior to radiofrequency ablation to identify the focus in the LAA.

RESULTS

The mechanism of LAA AT was automaticity in 11 and triggered activity in 2. The 13 LAA foci were located mainly at the LAA base: 11 on the medial side and 2 on the lateral side. Atrial activation sequences within the distal coronary sinus were helpful in differentiating these LAA foci. The criterion of a negative P wave in leads I and aVL indicating an LAA AT focus was associated with sensitivity of 92.3%, specificity 97.3%, positive predictive value 92.3%, and negative predictive value 97.3%. No complications occurred in any of the 13 patients. All 13 patients were free of atrial arrhythmias without any antiarrhythmic drugs during follow-up of 8 +/- 3 years.

CONCLUSION

LAA ATs have typical electrophysiologic and electrocardiographic characteristics that are helpful in guiding radiofrequency catheter ablation.

Atrial myocardial deformation properties are temporarily reduced after cardioversion for atrial fibrillation and correlate well with left atrial appendage function

AIM

This study was conducted to evaluate whether left atrial strain and strain rate correlate well with transesophageal parameters of stunning after atrial fibrillation.

METHODS AND RESULTS

Twenty-two consecutive patients with chronic atrial fibrillation >/=3 months and <1 year were enrolled in the study. Transthoracic (TTE) and transesophageal (TEE) echocardiography with color Doppler myocardial imaging were performed before, 1 day after and 10 days after successful cardioversion. Left atrial transthoracic strain (S) and strain rate (SR) from lateral, inferior and anterior atrial walls, left atrial appendage tissue velocities, strain and strain rate values were measured with offline analysis. Left atrial appendage emptying (LAAEV) and filling (LAAFV) velocities were obtained from transesophageal echocardiography. Left atrial transthoracic, and left atrial appendage strain and strain rates were significantly lower following 1 day after cardioversion (TTE S/SR, 5.0 +/- 2.8%/2.3 +/- 1.0; TEE (septal) S/SR, 7.6 +/- 3.6%/1.6 +/- 0.7). There was a good correlation between these parameters and LAAEV (LA systolic strain and LAAEV, r = 0.73, P = 0.007). Left atrial and LAA strain and strain rate values improved over time, and correlated well with LAAEV, measured 10 days after cardioversion.

CONCLUSIONS

Transthoracic atrial and TEE LAA strain and strain rate, which are quantitative measures of atrial function, are reduced after cardioversion, and recover subsequently. The good correlation between LAA function and TTE strain and strain rate suggests that TTE atrial parameters may help determine duration of anticoagulation.

The Time Interval from the Initiation of the P-Wave to the Start of Left Atrial Appendage Ejection Flow: Does It Reflect ?nteratrial Conduction Time?

Recurrence of atrial fibrillation is more common in patients with atrial conduction delay. In the present study, we evaluated whether findings obtained from transesophageal echocardiography (TEE), a semi-invasive method, correlate with those from an invasive method, electrophysiologic study (EPS), in measuring interatrial conduction time.

METHODS AND RESULTS

We compared two methods of calculating interatrial conduction time in a group of 33 patients. The origin of the P-wave on the surface electrocardiogram (ECG) was taken as the onset of atrial activation. The time interval from this point to the commencement of the left atrial appendage ejection flow (P-LAA) was measured by TEE. Meanwhile, simultaneous recordings of the left atrial appendage were obtained with a catheter positioned in the LAA, and an invasive interatrial conduction time was measured from the origin of the surface's earliest P-wave (I-IACT). The mean I-IACT (46.27 +/- 13.25 ms) correlated strongly with the mean P-LAA (49.91 +/- 12.72 ms; r = 0.839, P < 0.0001).

CONCLUSION

The interatrial conduction time can be estimated with a relatively noninvasive method using P-LAA measurements. This technique can be applied widely in predicting AF recurrence, and appropriate therapy may be applied.

Echocardiographic Evaluation of the Left Atrium and Left Atrial Appendage Function in Patients with Atrial Septum Aneurysm - Implications for Thromboembolic Complications

BACKGROUND

Our study aimed to assess left atrium (LA) and left atrial appendage (LAA) function in patients with atrial septum aneurysm (ASA) and to relate it to thromboembolic complications.

METHODS

The study group comprised 25 patients with isolated ASA (group I) and 17 clinically healthy subjects (control group = group II). Transthoracic and transesophageal echocardiography were performed in all investigated patients.

RESULTS

In group I, the following parameters were significantly higher than in the controls: LA minimal dimension (LA (min)) was 2.13 vs. 1.7 cm; LA presystolic dimension (LA (a)) was 2.66 vs. 2.29 cm and LA pre-ejection period/LA ejection time index (PEP/ETLA) was 1.26 vs. 0.41 ( P < 0.05). There were no statistically significant differences between groups as to P wave and PR-interval duration, which were 69 vs. 72 ms and 167 vs. 173 ms, respectively. All LAA parameters were investigated, but LAA minimal areas (LAA (area min)) were higher in the study group than in controls: LAA transversal dimension (LAA (trans)) was 1.89 vs. 1.32 cm; LAA longitudinal dimension (LAA (long)) was 4.24 vs. 3.11 cm; LAA maximal area (LAA (area max)) was 4.35 vs. 3.1 cm (2); LAA ejection fraction (EFLAA) was 56 vs. 33 %; LAA peak emptying (LAAE) was 0.64 vs. 0.41 m/s, and filling velocities (LAAF) was 0.55 vs. 0.42 m/s ( P < 0.05). The results indicate a depression of LA systolic and an enhancement of LAA function in patients with ASA compared with clinically healthy subjects.

CONCLUSION

(1) Atrial septum aneurysm impairs left atrium systolic function. (2) In patients with atrial septum aneurysm, left atrium appendage function changes; its systolic as well as a reservoir function improve. (3) The enhancement of LAA function in ASA may be a compensatory mechanism for LA systolic function deterioration. (4) As LAA systolic function is enhanced, it is rather unlikely that LAA is the place of origin of thrombi, which occur relatively frequently (according to the literature) in patients with ASA. The thrombi seem to be formed in the bulging sack of ASA, i.e., in the part of the LA whose systolic function is depressed.

Strain and Strain Rate Imaging in Evaluating Left Atrial Appendage Function by Transesophageal Echocardiography

BACKGROUND

This study was planned to assess whether strain rate (Sr) and strain (S) echocardiography is a useful method for functional assessment of the left atrial appendage (LAA).

MATERIAL AND METHODS

Fifty-seven consecutive patients underwent a clinically indicated study. LAA late empty velocity (LAAEV) was calculated as a gold standard for left atrial appendage function. Real-time 2-dimensional color Doppler myocardial imaging data were recorded from the LAA at a high frame rate. Analysis was performed for LAA longitudinal strain rate and strain from midsegment of lateral wall of LAA. LAA strain determines regional lengthening expressed as a positive value or shortening expressed as a negative value. Peak systolic values were calculated from the extracted curve.

RESULTS

Spearman correlation test results showed a statistically significant positive correlation was between the S, Sr variables and LAAEV (LAAEV vs S; r = 0.886, P < 0.001; LAAEV vs Sr: r = 0.897, P < 0.001, respectively). Strain and strain rate values were also significantly lower in patients with spontaneous echocardiographic contrast when compared with those without (strain; 2.42 +/- 0.98 vs 13.1 +/- 5.9, P < 0.001 and strain rate: 0.97 +/- 0.54 vs 3.34 +/- 1.15, P < 0.001, respectively). In addition, LAA strain and strain rate values were significantly lower in the patients with LAA thrombus (strain; 2.15 +/- 0.96 vs 8.35 +/- 6.9, P < 0.001, strain rate; 0.79 +/- 0.46 vs 2.30 +/- 1.48, P < 0.001, respectively).

CONCLUSION

S and Sr imaging can be considered a robust technique for the assessment of the LAA systolic deformation.

Systolic Tissue Velocity Is a Useful Echocardiographic Parameter in Assessment of Left Atrial Appendage Function in Patients with Mitral Stenosis

BACKGROUND

The incidence of thromboembolism remains high in patients with mitral stenosis (MS). The left atrial appendage (LAA) is a potential site for development of thrombus and LAA dysfunction is an independent predictor of thromboembolism. The LAA dysfunction is represented by reduced LAA late emptying velocity. But the magnitude of LAA flow velocities is dependent on acute changes in loading conditions.

AIM

To investigate the value of the LAA tissue velocities obtained by tissue Doppler imaging (TDI) in assessment of LAA function in MS patients with and without thromboembolic events.

METHODS

The study population consisted of 98 isolated MS patients of 32 age and sex-matched healthy controls. All subjects underwent transesophageal echocardiography (TEE). LAA late peak emptying (LAAEV) and filling (LAAFV) flow velocities were recorded. LAA peak late tissue systolic (LSV) and diastolic (LDV) tissue velocities by TDI were measured. The patients were divided into three groups as Group I (n = 38, sinus rhythm and LAAEV > or = 25 cm/s), Group II (n = 26, sinus rhythm and LAAEV < 25 cm/s), and Group III (n = 34, atrial fibrillation).

RESULTS

Twenty-one patients had thromboembolic events. LAAEV, LAAFV, LSV, and LDV were significantly reduced in patients with embolic events. Spontaneous echo contrast (SEC) density was strongly negative correlated with LSV, whereas weakly negative correlated with LAAEV. Multivariate regression analysis showed that LSV and the presence of SEC were independently associated with embolic events.

CONCLUSION

LSV seems more reliable and useful parameter in evaluating LAA function. LAA function is more depressed among patients with embolic events.

Dual-site right atrial pacing increases left atrial appendage flow in patients with sick sinus syndrome and paroxysmal atrial fibrillation

BACKGROUND

Dual-site right atrial pacing has been proposed as a promising concept for prevention of paroxysmal atrial fibrillation (PAF). Effects of this pacing configuration on left atrial appendage (LAA) flow and transmitral flow may be of prognostic and hemodynamic relevance. This study aims to characterize acute changes in left atrial flow depending on dual-site right atrial pacing.

METHODS

In 12 patients (66 +/- 8.8 years, 4 women) with PAF and sinus bradycardia a pacemaker with a right atrial dual-site lead configuration (right atrial lateral and coronary sinus ostium) was implanted. Flow velocities in the left pulmonary vein (LPV), LAA, and across the mitral valve were assessed by transesophageal echocardiography and compared during sinus rhythm (SR) and dual-site (DS) pacing.

RESULTS

Dual-site pacing resulted in higher maximum (SR: 0.57 m/s; pacing: 0.77 m/s; P < 0.02) and mean (SR: 0.33 m/s; DS: 0.47 m/s; P < 0.01) LAA emptying flow when compared with SR. The passive transmitral flow component (maximum E-wave velocity) was lower during dual-site pacing (SR: 0.53 m/s vs DS: 0.44 m/s, P < 0.02). The E/A ratio tended to be lower during dual-site pacing (SR: 1.21 vs DS: 1.01, P = 0,10). LPV flow velocities during SR and DS pacing did not differ.

CONCLUSION

DS right atrial stimulation in patients with PAF increases the LAA emptying flow velocity and shifts the transmitral flow pattern towards a lower passive component when compared with sinus rhythm. The change in LAA flow may contribute to a lower incidence of thromboembolism and merits further investigation.

Carvedilol Therapy Is Associated with an Improvement in Left Atrial Appendage Function in Patients with Congestive Heart Failure

Heart failure is one of the leading death reasons in the world. Left atrial appendage (LAA) is of great importance in maintaining cardiac function. We examined the effect of carvedilol therapy on left atrial appendage functions in patients with symptomatic congestive heart failure. Twenty patients with symptomatic congestive heart failure and resting ejection fraction < or = 40% were included in this study. LAA was visualized by transesophageal echocardiography. LAA area change (LAAAC), LAA empty velocity (LAAEV) and LAA empty velocity time integral (LAAEVTI) were calculated as the average of five cardiac cycles. A minimum dose of carvedilol administered to each patient, was titrated up to maximal dose that the patients could tolerate, during an 8-week period. After the third month of completing treatment, a second transthoracic and transesophageal echocardiographic study was performed. Heart rate (P < 0.001), systolic (P = 0.002) blood pressures were reduced by carvedilol therapy at the end of the third month. LAAEV (P < 0.001), LAAEVTI (P < 0.001), and LAAAC (P < 0.001) were significantly increased at the end of the third month of carvedilol therapy. This study indicates that in patients with symptomatic congestive heart failure, carvedilol therapy is associated with an improvement in left atrial appendage function.

Radiofrequency catheter ablation for atrial tachycardia originating from the left atrial appendage

A 36-year-old woman presented with drug-refractory atrial tachycardia. During the tachycardia episodes, P waves were positive in leads II, III, aVF, and V1, while they were negative in leads I and aVL. It was hard to determine whether the origin was the left atrial appendage or left superior pulmonary vein on the surface electrocardiogram. Electrophysiologic evaluation revealed that the earliest endocardial activation occurred at the base of the left atrial appendage, preceding the onset of P waves by 38 ms. On initiation of the tachycardia, a warm-up phenomenon was observed. There was a fixed relation between the coupling interval of a single extrastimulus and the return cycle length during the tachycardia. These findings suggested that the mechanism of the tachycardia was automaticity. Application of radiofrequency energy at the left atrial appendage terminated the tachycardia and it was not inducible after ablation.

Focal Atrial Tachycardias Arising from the Right Atrial Appendage: Electrocardiographic and Electrophysiologic Characteristics and Radiofrequency Ablation

OBJECTIVE

To characterize the electrocardiographic and electrophysiological features and frequency of focal atrial tachycardia (AT) originating from the right atrial appendage (RAA).

BACKGROUND

The RAA has been described as a site of origin of AT, but detailed characterization of these tachycardias is limited.

METHODS

Ten patients (3.8%) of 261 undergoing radiofrequency ablation (RFA) for focal AT are reported. Endocardial activation maps (EAM) were recorded from catheters at the CS (10 pole), tricuspid annulus (20 pole Halo catheter), and His positions. P waves were classified as negative, positive, isoelectric, or biphasic.

RESULTS

The mean age was 39 +/- 20 years, nine males, with symptoms for 4.1 +/- 5.1 years. Tachycardia was incessant in seven patients, spontaneous in one patient, and induced by programmed extrastimuli in two patients. These foci had a characteristic P wave morphology. The P wave was negative in lead V(1) in all patients, becoming progressively positive across the precordial leads. The P waves in the inferior leads were low amplitude positive in the majority of patients. Earliest EAM activity occurred on the Halo catheter in all patients. Mean activation time at the successful RFA site =-38 +/- 15 msec. Irrigated catheters were used in six patients, due to difficulty achieving adequate power. RFA was acutely successful in all patients. Long-term success was achieved in all patients over a mean follow up of 8 +/- 7 months.

CONCLUSIONS

The RAA is an uncommon site of origin for focal AT (3.8%). It can be suspected as a potential anatomic site of AT origin from the characteristic P wave and activation timing. Irrigated ablation catheters are often required for successful ablation. Long-term success was achieved with focal ablation in all patients.

Left atrial appendage functions in patients with severe rheumatic mitral regurgitation

AIM

The left atrial appendage (LAA) function was evaluated in patients with severe rheumatic mitral regurgitation, having sinus rhythm or atrial fibrillation, by standard and tissue Doppler echocardiographic examinations.

METHODS AND RESULTS

Sixty patients with rheumatic severe mitral regurgitation were enrolled. The patients (14 females and 6 males) having sinus rhythm were selected as group I and 20 patients (15 females and 5 males) with atrial fibrillation formed group II. 20 healthy subjects (15 female and 5 males) served as the control group (group III). In order to determine the LAA functions, LAA peak filling flow velocity (LAAPFV), LAA peak emptying flow velocity (LAAPEV) and percentage of LAA area change (LAAAC %) were measured. In the TDI records of the subjects with sinus rhythm, the first positive wave identical to the LAA late emptying wave (LEW) following the P-wave was accepted as LAA late systolic wave (LSW), and the second negative wave identical to the LAA late filling flow was accepted as late diastolic wave (LDW). In patients with atrial fibrillation, the positive wave was accepted as LAA late systolic wave (LSW), and the second negative wave identical to the LAA late filling flow was accepted as late diastolic wave (LDW). LAA outflow and inflow velocities were lower in the group having atrial fibrillation (P < 0.002, and P < 0.007, respectively). LAAAC% was also reduced in group II (P < 0.0001). The pulsed Doppler LSW and LDW velocities, measured with TDI method were found to be quite reduced in patients with AF (P: 0.002 and P: 0.001, respectively). The study parameters were statistically similar in patients with normal sinus rhythm and controls.

CONCLUSION

In this study, we found that the LAA functions are impaired in patients with severe mitral regurgitation, having AF, whereas preserved in patients with normal sinus rhythm, compared to controls.

Relationship between Slow Coronary Flow and Left Atrial Appendage Blood Flow Velocities

AIMS

This study was undertaken to assess whether slow coronary flow (SCF)is related to low left atrial appendage (LAA) blood flow velocities.

METHODS

Study subjects consist of 44 patients with SCF and 11 volunteer subjects with normal coronary angiogram. The diagnosis of SCF was made using the TIMI frame count method. The blood flow velocities were obtained by placing a pulsed-wave Doppler sample volume inside the proximal third of the LAA.

RESULTS

The mean LAA emptying velocities (MEV)were significantly lower in patients than control subjects (34.5 +/- 9.9 cm/sec vs 84.0 +/- 12.1 cm/sec; P < 0.001). In bivariate analysis, significant correlation was found between MEV, and systolic pulmonary venous flow, mean TIMI frame count, deceleration time, and isovolumetric relaxation time (P < 0.05). By multiple linear regression analysis, mean TIMI frame count (beta=-0.865, P < 0.001) was identified as independent predictors of MEV.

CONCLUSION

This study indicates that SCF phenomenon may be related to low LAA blood flows.

Identifying far-field superior vena cava potentials within the right superior pulmonary vein

BACKGROUND

Far-field extra-pulmonary vein (PV) potentials originating from the left atrial appendage and adjacent left atrium have been identified within the left PVs, but no systematic study of extra-PV potentials within the right superior PV (RSPV) has been described.

OBJECTIVES

The purpose of this study was to prospectively analyze extra-PV contributions to RSPV potentials.

METHODS

In a consecutive, prospective series of 114 patients (96 men and 18 women; 56 +/- 10 years) undergoing electrophysiologically guided ostial PV isolation, residual potentials recorded with a circular mapping catheter in the RSPV after ostial isolation were analyzed. Their extra-PV origin was validated by mapping a site with identical timing (in sinus rhythm or atrial fibrillation) within the adjacent superior vena cava (SVC) where, in sinus rhythm, local pacing (until threshold amplitude) concealed the residual potential within the stimulus artifact because of very short activation timing. The timing of residual potentials with respect to surface ECG P-wave onset was measured and compared with the earliest timing of ablated RSPV potentials.

RESULTS

Residual low-amplitude (mean 0.29 +/- 0.17 mV, range 0.07-0.65 mV) extra-PV potentials were recorded from the anterior and superior aspect of the RSPV in 3.6 +/- 1 bipoles in 26 (23%) patients (all men, 51 +/- 10 years) with a timing from sinus P-wave onset of 17 +/- 12 ms (range 0-40 ms) vs 52 +/- 9 ms (range 35-70 ms) for the earliest RSPV potential (P <.001, t-test). Extra-PV potentials all originated from the posterior aspect of the SVC. The SVC potential was identified during ongoing atrial fibrillation in eight patients and later confirmed in sinus rhythm. An extra-PV potential of SVC origin could be identified by timing earlier than 30 ms from onset of the sinus P wave, with sensitivity of 92%, specificity 100%, positive predictive value 100%, and negative predictive value 89%.

CONCLUSION

Extra-PV potentials of right-sided SVC origin were recorded within the RSPV in 23% of patients and can be identified with high sensitivity and specificity by a timing within 30 ms of sinus P-wave onset. Recognizing these potentials can avoid unnecessary additional ablation and possibly PV stenosis or phrenic paralysis.

Mitral Annular Systolic Velocity Reflects the Left Atrial Appendage Function in Mitral Stenosis

BACKGROUND

Left atrial appendage (LAA) dysfunction is an independent predictor of thromboembolism in mitral stenosis (MS).

OBJECTIVES

To investigate whether there is a relation between annular velocities obtained by tissue Doppler imaging and LAA function and to determine if the annular velocities can predict the presence of the inactive LAA in MS.

METHODS

Eighty-five MS patients and 80 healthy controls were evaluated by transthoracic echocardiography and all patients underwent transesophageal echocardiography. The annular systolic (S-wave) and diastolic (E- and A-waves) velocities were recorded. Inactive LAA was defined as LAA emptying velocity <25 cm/sec. Patients were divided into three groups; group I (n = 43): sinus rhythm (SR) and LAA emptying velocity > or =25 cm/sec, group II (n = 15): SR and LAA emptying velocity <25 cm/sec and group III (n = 27): atrial fibrillation.

RESULTS

Thrombus was detected in 12 patients and spontaneous echo contrast (SEC) was detected in 48 patients. Both S-wave and peak LAA emptying velocities were decreasing, while SEC frequency and density were increasing from group I to group III. There was a positive correlation between LAA emptying and S-wave velocities (P < 0.001, r = 0.682). Multivariate regression analysis showed that only S-wave is the independent predictor of inactive LAA (P = 0.001, odds ratio = 0.143, 95% CI = 0.047-0.434). In patients with SR, the cutoff value of S-wave was 13.5 cm/sec for the prediction of the presence of inactive LAA (sensitivity: 95.3%, specificity: 93.3%).

CONCLUSIONS

S-wave is an independent predictor of inactive LAA and a useful parameter in estimating inactive LAA in MS with SR.

Antithrombotic therapy in atrial fibrillation: beyond the AFFIRM study

In the last few decades several clinical studies evaluated the efficacy and safety of different strategies for antithrombotic prophylaxis to prevent thromboembolic events in patients with atrial fibrillation (AF). Nowadays, a frequently debated point is related to the high embolic risk deriving from the asymptomatic and symptomatic AF recurrence after cardioversion or in paroxysmal AF, especially in patients with a large number of prolonged episodes of AF. In fact, after the recent AFFIRM and RACE trials, patients after successful cardioversion at risk for thromboembolism could also need lifelong anticoagulation. Considering this, should we anticoagulate all patients with clinical risk factors for thromboembolism with a single episode of AF, without considering the hemorrhagic risk? Based on recent trials, it is reasonable to hypothesize that long AF recurrences (> 48 h), both symptomatic and asymptomatic, are present mostly (if not exclusively) in patients with structural left atrial appendage (LAA) dysfunction and remodeling. Conversely, AF recurrences in patients without LAA dysfunction and remodeling, could be too short to allow thrombi formation in the LAA, and the anticoagulation could also be avoided. Once other clinical and echocardiographic determinants of stroke have been excluded, the LAA velocity could select patients with a normal appendage function at low embolic risk who could benefit from anti-aggregation and patients with irreversible appendage dysfunction, at high embolic risk, who need lifelong anticoagulation.

Electrophysiological pulmonary vein antrum isolation with a multielectrode basket catheter is feasible and effective for curing paroxysmal atrial fibrillation: Efficacy of minimally extensive pulmonary vein isolation

BACKGROUND

How extensive should an appropriate pulmonary vein (PV) ablation be is a matter of controversy.

OBJECTIVE

The study's aim was to investigate the efficacy of minimally extensive PV ablation for isolating the PV antrum (PVA) with the guidance of electrophysiological parameters.

METHODS

Fifty-five consecutive symptomatic paroxysmal atrial fibrillation (PAF) patients underwent PV mapping with a multielectrode basket catheter (MBC). A 31-mm MBC was deployed in 3-4 PVs as proximally as possible without dislodgement, and the longitudinal PV mapping enabled us to recognize single sharp potentials formed by the total fusion of the PV and left atrial potentials around the PV ostium or the transverse activation patterns that were observed. Those potentials were defined as PVA potentials. Radiofrequency ablation was performed circumferentially targeting PVA potentials with the end point being their elimination.

RESULTS

After circumferential PVA ablation, electrical disconnection was achieved in 77% and residual PVA conduction gaps were observed in 23% of all targeted PVs. Those residual conduction gaps were mainly located at the border between ipsilateral PVs (42%) and between the left PVs and left atrial appendage (33%) and were eliminated by a mean of 3 +/- 2 minutes of local radiofrequency deliveries. During the follow-up period (11 +/- 5 months), 46 (84%) patients were free of symptomatic PAF without any anti-arrhythmic drugs. No PV stenosis or spontaneous left atrial flutter occurred.

CONCLUSIONS

Electrophysiological PVA ablation with an MBC is feasible and effective for curing PAF because this minimally extensive PVA isolation technique targets the optimal sites, achieving both high efficacy and safety.

Left Atrial Appendage-Flow Velocity Predicts Cardioversion Success in Atrial Fibrillation

Restoration of sinus rhythm by electrical cardioversion is a therapeutic option in appropriately selected patients with atrial fibrillation. It is important to determine predictors of electrical cardioversion outcome in patients with atrial fibrillation. Predictive value of clinical and conventional echocardiographic parameters for predicting cardioversion outcome is limited. The role of left atrial appendage (LAA) function, which may reflect left atrial contractile function, for prediction of cardioversion outcome remains unclear. We conducted a single center prospective study to evaluate the role of LAA function for prediction of cardioversion success in patients with atrial fibrillation. One hundred sixty three patients with atrial fibrillation underwent transthoracic and transesophageal echocardiography (TEE) before electrical cardioversion. LAA functions, including LAA peak flow velocity, LAA area and LAA ejection fraction, were examined. Cardioversion was successful in 133 patients and unsuccessful in 30 patients. Mean LAA peak emptying flow velocity was significantly higher in the patients with successful cardioversion than in those with unsuccessful cardioversion (0.34 +/- 0.14 vs 0.27 +/- 0.1 m/sec; p = 0.013). At multivariate logistic regression analysis, only LAA flow velocity (> 0.28 m/sec, odds ratio = 2.8 ; p = 0.03) proved to be an independent predictor of cardioversion success. LAA area (p = 0.18) and LAA ejection fraction (p = 0.52) were not different between successful and unsuccessful cardioversion groups. Therefore, measurement of LAA flow velocity provides valuable information for prediction of cardioversion outcome in patients with atrial fibrillation before TEE guided cardioversion.

Transthoracic Echocardiographic Predictors of the Left Atrial Appendage Contraction Velocity in Stroke Patients with Sinus Rhythm

Systemic embolization is a potential complication in patients with thrombi situated in the left atrium and particularly, in the left atrial appendage (LAA). Reduced LAA contraction velocities, determined by the transesophageal echocardiography (TEE), are associated with increased risk of LAA spontaneous echocontrast and thrombus formation, and a history of systemic embolism. However, TEE remains a semi-invasive procedure, limiting its serial application as a screening tool. Therefore, it is desirable to obtain information regarding LAA function by transthoracic echocardiography in patients having cardioembolic stroke. The present study was designed to investigate various echocardiographic variables for patients with stroke to predict LAA dysfunction, reflected as reduced LAA contraction velocity. We studied a total of 61 patients with newly diagnosed acute embolic stroke (42 patients) and transient ischemic attack (19 patients). Computerized tomographic scanning was performed for the diagnosis of embolic stroke. Left atrial functional parameters determined by transthoracic echocardiography, such as left atrial active emptying fraction and acceleration slope of mitral inflow A wave, had significant correlations with the LAA contraction velocity (r = 0.57, p < 0.001; r = 0.54, p < 0.001, respectively). Left atrial volume index, left atrial active emptying volume and left atrial fractional shortening were also correlated with LAA contraction velocity (r = -0.44, p < 0.001; r = 0.38, p = 0.003; r = 0.37, p = 0.004, respectively). In conclusion, transthoracic echocardiography can provide valuable and reliable information about the LAA contraction velocity in stroke patients with sinus rhythm. This finding gives new insights for the appropriate strategy in the evaluation of an acute ischemic stroke.

Higher Levels of Serum Fibrin-Monomer Reflect Hypercoagulable State and Thrombus Formation in the Left Atrial Appendage in Patients With Acute Ischemic Stroke

BACKGROUND

It is sometimes difficult to make a diagnosis of cardioembolic stroke in the stroke care unit, because of the splashing and vanishing of the intracardiac source of the emboli on transesophageal echocardiography. Serum fibrin-monomer (FM) is a new marker for coagulation activity that is useful for identifying older individuals at increased risk of ischemic stroke.

METHODS AND RESULTS

Two hundred and four patients with acute ischemic stroke were examined for serum coagulation and fibrinolytic activity on admission, and underwent transesophageal echocardiography within 7 days of onset. Serum levels of FM was significantly higher in patients with left atrial appendage (LAA) thrombus formation (n=24) than in those with no thrombus (88+/-52 vs 14+/-9 microg/ml, p<0.0001). On multivariate logistic regression analysis, FM was an independent predictor for LAA thrombus (RR 2.975, 95% confidence interval 1.114 to 4.820, p=0.0214). In patients with LAA thrombus negative group, cases with LAA emptying flow velocity at atrial systole that was absent or smaller than at early diastole had significantly higher FM levels as compared to cases with larger velocity (42+/-12 vs 8+/-5 microg/ml, p<0.0001).

CONCLUSION

Higher levels of serum FM reflect LAA flow pattern alterations and thrombus formation in patients with acute ischemic stroke.

[Influence of age of patients with atrial fibrillation on left atrium function]

Frequency of occurrence of atrial fibrillation (FA) increases with age. In the elderly this arrhythmia might influence the enlargement and function of left atrium (LA) and its appendage (LAA). The aim of this study was to assess the association between age of patients and selected echocardiographic parameters concerning left atrium.

MATERIAL AND METHODS

120 consecutive patients (52 women and 68 men) with FA were studied 36-89 years old (mean 68.7 +/- 10.9). Patients were divided into two groups using a cut-off value age of 70 years. Older than 70 years were 64 patients, whereas below this age were 56 persons. Duration time of arrhythmia did not differ significantly between studied groups. In all patients transthoracic (TTE) and transoesophageal (TEE) echocardiography were performed to assess selected echocardiographic parameters concerning left atrium (LA) and its appendage (LAA). During TTE were measured: LA maximal diameter in M-mode (LAmax), LA transversal diameter in 4-CH (LAtrans), LA longitudinal diameter in 4-CH (LAlong), LA circulum in 4-CH (LAcirc), LA area in 4-CH (LAarea). Consequently TEE was done to assess LAA transversal diameter (LAAtrans), LAA longitudinal diameter (LAAlong), LAA circulum (LAAcirc), LAA area (LAAarea), spontaneous echocardiographic contrast (SEC), thrombus (THR), maximal LAA outflow velocity (LAAF), maximal LAA inflow velocity (LAAB), integral of LAA outflow velocity (LAAFintg) and integral of LAA inflow velocity (LAABintg).

RESULTS

LAmax (4.91 +/- 0.61 vs. 4.22 +/- 0.49), LAtrans (4.75 +/- 0.71 vs. 4.11 +/- 0.44) and LAarea (31.85 +/- 6.9 vs. 27.51 +/- 6.54) were significantly greater in older patients compared to those below 70 years old. LAlong, LAcirc, LAarea, LAA trans, LAAlong, LAAcirc did not differ between studied groups. Thrombi in LAA were detected rarely in study population and were found often in older patients (in 2 vs. 6 patients). In almost 2/3 older patients SEC in LAA was visualized, which was markedly frequent when compared to younger group. In older patients parameters characterizing LAA function had significantly lower values than in younger patients (LAAF respectively 19.8 +/- 9.16 vs. 28.57 +/- 10.7, LAAB respectively 21.6 +/- 8.12 vs. 31.81 +/- 10.88).

CONCLUSIONS

In patients with atrial fibrillation left atrium and its appendage diameters are greater in the elderly. Left atrium appendage function is more deteriorated in older patients with atrial fibrillation. During atrial fibrillation thrombus formation and appearance of spontaneous echocardiographic contrast is more often in the elderly.

Techniques, Evaluation, and Consequences of Linear Block at the Left Atrial Roof in Paroxysmal Atrial Fibrillation

BACKGROUND

There are no reports describing the technique, electrophysiological evaluation, and clinical consequences of complete linear block at roofline joining the superior pulmonary veins (PVs) in patients with paroxysmal atrial fibrillation (AF).

METHODS AND RESULTS

Ninety patients with drug-refractory paroxysmal AF undergoing radiofrequency ablation were prospectively randomized into 2 ablation strategies: (1) PV isolation (n=45) or (2) PV isolation in combination with linear ablation joining the 2 superior PVs (roofline; n=45). In both groups, the cavotricuspid isthmus, fragmented peri-PV-ostial electrograms, and spontaneous non-PV foci were ablated. Roofline ablation was performed at the most cranial part of the left atrium (LA) with complete conduction block demonstrated during LA appendage pacing by the online mapping of continuous double potential and an activation detour propagating around the PVs to activate caudocranially the posterior wall of the LA. The effect of ablation at the LA roof was evaluated by the change in fibrillatory cycle length, termination and noninducibility of AF, and clinical outcome. PV isolation was achieved in all patients with no significant differences in the radiofrequency duration, fluoroscopy, or procedural time between the groups. Roofline ablation required 12+/-6 (median 11, range 3 to 25) minutes of radiofrequency energy delivery with a fluoroscopic duration of 7+/-2 minutes and was performed in 19+/-7 minutes. Complete block was confirmed in 43 patients (96%) and resulted in an activation delay that was shorter circumventing the left than the right PVs during LA appendage pacing (138+/-15 versus 146+/-25 ms, respectively; P=0.01). Roofline ablation resulted in a significant increase in the fibrillatory cycle length (198+/-38 to 217+/-44 ms; P=0.0005), termination of arrhythmia in 47% (8/17), and subsequent noninducibility of AF in 59% (10/17) of the patients inducible after PV isolation. However, LA flutter, predominantly perimitral, could be induced in 10 patients (22%) after roofline ablation. At 15+/-4 months, 87% of the roofline group and 69% with PV isolation alone are arrhythmia free without antiarrhythmics (P=0.04).

CONCLUSIONS

This prospective randomized study demonstrates the feasibility of achieving complete linear block at the LA roof. Such ablation resulted in the prolongation of the fibrillatory cycle, termination of AF, and subsequent noninducibility and is associated with an improved clinical outcome compared with PV isolation alone.

Predictors of left atrial spontaneous echocardiographic contrast or thrombus formation in stroke patients with sinus rhythm and reduced left ventricular function

The objective of the present study was to identify predictors of left atrial spontaneous echocardiographic contrast (SEC) or thrombus in patients with stroke with sinus rhythm and left ventricular dysfunction. Of 500 consecutive patients with stroke, 48 with sinus rhythm and reduced left ventricular ejection fractions (EFs) < or =45% were examined. Ten patients presented with SEC or thrombus. The patients with SEC or thrombus had larger left atrial diameters (47 +/- 4 vs 42 +/- 6 mm, p <0.05), smaller EFs (30 +/- 9% vs 38 +/- 8%, p <0.01), and slower left atrial appendage (LAA) flow velocities (42 +/- 13 vs 61 +/- 17 cm/s, p <0.01). Multivariate analysis identified EF < or =35% and LAA flow velocity < or =55 cm/s as predictors of SEC or thrombus (p <0.05). Patients with stroke with sinus rhythm and moderate- to high-grade reduction of the left ventricular EF represent a risk group for a left atrial source of embolism and should undergo transesophageal echocardiography.

Surgical Closure of the Left Atrial Appendage – A Beneficial Procedure?

BACKGROUND

Closure of the fibrillating left atrial appendage (LAA) has been recommended during valve surgery to decrease the risk of arterial embolism. However, patients undergoing surgical LAA closure have not systematically been reevaluated for complete LAA obliteration.

METHODS AND RESULTS

During a 12-month period, we studied 6 consecutive patients with paroxysmal (n = 3) or permanent (n = 3) atrial fibrillation who underwent surgical LAA closure at the time of valve surgery. Transesophageal echocardiography (TEE) performed 23-159 days (mean 51) postoperatively demonstrated complete LAA closure in only 1 patient. In 5 patients, incomplete LAA closure was found due to disruption of the closure line. The size of the residual LAA orifice ranged from 3 to 20 mm. There was a high flow velocity at the LAA orifice (0.33-2.2 m/s), whereas flow in the LAA body was low (<0.2 m/s). Spontaneous echocardiographic contrast (SEC) in the LAA had newly developed (n = 3) or was much more intense than preoperatively (n = 2). Despite therapeutic anticoagulation 2 patients showed a LAA thrombus which had not been present on the preoperative TEE, and 1 patient with SEC suffered a stroke 4 weeks after attempted LAA closure.

CONCLUSION

Surgical LAA closure was incomplete in most patients, resulting in blood stagnation and an increased likelihood of clot formation. Incomplete surgical LAA closure, therefore, may promote rather than reduce the risk of stroke. Intraoperative TEE is mandatory to verify complete LAA obliteration.

The Left Atrial Appendage, a Small, Blind-Ended Structure

The increasing prevalence of stroke and atrial fibrillation is a stimulus for new therapeutic strategies and also warrants a review of imaging modalities of the most important source of cardiac systemic embolic events: the left atrial appendage (LAA). This blind-ended, complex structure is embryologically distinct from the body of the left atrium and is sometimes regarded as just a minor extension of the atrium. However, it should routinely be analyzed as part of a transesophageal echocardiographic (TEE) examination. A pulsed Doppler TEE analysis of LAA emptying flow should supplement a two-dimensional (2-D) analysis; these examinations have proven to be highly reproducible and to help assess thromboembolic risk. In 2-D imaging, potential thrombus and spontaneous echo contrast should be sought. In addition, LAA plays a hemodynamic role that participates in atrial function and is influenced by various hemodynamic conditions. In view of the embolic risks from a dysfunctional appendage, the LAA is often ligated during cardiac valve surgery. New devices are under evaluation for percutaneous closure of the LAA, and further studies should improve the definition, understanding, and treatment of LAA dysfunction.

The effect of gliclazide and glibenclamide on preconditioning of the human myocardium

The cardioprotection of ischaemic preconditioning may be abolished in diabetic patients especially when some oral hypoglycaemics are used. The dose-response effect of gliclazide and glibenclamide on ischaemic preconditioning and the action of glibenclamide on signal transduction in human myocardium were investigated using right atrial appendages from cardiac surgery patients. Glibenclamide (0.1, 1, 3 and 10 microM) and gliclazide (1, 10, 30 and 100 microM) were added for 10 min prior to ischaemic preconditioning. The cardioprotection was abolished by glibenclamide at all concentrations and by gliclazide at supratherapeutic concentrations of 30 and 100 microM. Glibenclamide abolished the protective effect of mitoK(ATP) channel opening but not that of protein kinase C (PKC) or p38 mitogen activated protein kinase (p38MAPK) activation. In conclusion, glibenclamide and gliclazide differential effects may be a result of differential sensitivities. Glibenclamide does not block protection conferred by either PKC or p38MAPK activation. These findings may have clinical implications in ischaemic heart disease.

Comparison of frequency of thromboembolic events and echocardiographic findings in patients with chronic nonvalvular atrial fibrillation and coarse versus fine electrocardiographic fibrillatory waves

In patients with nonvalvular atrial fibrillation, the electrocardiographic fibrillatory wave reflects the structural and electrical remodeling of the atria. This study examined whether the fibrillatory wave amplitude could predict the risk of thromboembolism and demonstrated that this amplitude was related to the duration of atrial fibrillation. We also showed that the presence of fine fibrillatory waves (<1 mm in amplitude) could predict the thromboembolic potential in patients with chronic nonvalvular atrial fibrillation.

[Functional assessment of the left atrial appendage with transesophageal echocardiography before and after percutaneous valvotomy in the mitral stenosis]

OBJECTIVE

To assess the effects of the relief of the mitral stenosis by percutaneous ballon valvotomy in the function of the left atrial appendage.

METHODS

Twelve patients with symptomatic mitral stenosis, in sinus rhythm, were studied. They were submitted to the transesophageal echocardiogram before and after effective percutaneous ballon valvotomy. Concerning the left atrial appendage, the peak flow velocities and the respective integral of the anterograde and retrograde flow, in addition to the ejection fraction calculated through the planimetry of the area of that structure, were analyzed at the pulsatile Doppler.

RESULTS

There was a significant increase of the anterograde flow velocity of the left atrial appendage after percutaneous ballon valvotomy (pre: mean of 0.30 m/s; post: mean of 0.47 m/s; p<0.05) and their respective integrals. The same happened with the retrograde flow velocity (pre: mean of 0.35 m/s, post: mean of 0.53 m/s; p<0.05). There was a tendency of increase of the ejection fraction of the left atrial appendage after the procedure (pre: mean of 20%, post: mean of 31%; p=0.08).

CONCLUSION

The effective opening of the stenosed mitral orifice resulting from the percutaneous ballon valvotomy determined an improvement of the flow pattern of the left atrial appendage, which can potentially contribute for the reduction of the embolic risk.

Effect of cardiac resynchronization therapy on left atrial appendage function and pulmonary venous flow pattern

BACKGROUND

Previous studies have shown improvement in left ventricular function and development of the reverse remodeling in the left ventricle and left atrium after cardiac resynchronization therapy (CRT). The aim of this study was to investigate the effect of CRT on left atrial appendage (LAA) function and pulmonary venous flow pattern.

METHODS

Eighteen patients with systolic heart failure and complete left bundle branch block underwent implantation of biventricular pacemaker devices. In order to follow changes in LAA, transthoracic and transesophageal echocardiographic examinations were performed 1 week before and repeated 1 and 6 months after pacemaker implantation.

RESULTS

CRT resulted in significant clinical improvement and decrease in NYHA functional class in 17 patients (94%). Maximum and minimum areas of left atrial appendage (LAAAmax and LAAAmin) decreased, with a concomitant increase in LAA ejection fraction. [LAAAmax: from 4.6+/-2 to 4.2+/-1.8 cm2 at the first (P < 0.001) and to 4.0+/-1.8 cm2 at the sixth month (P < 0.001); LAAAmin: from 2.7+/-1.3 to 2.3+/-1.2 cm2 at the first (P < 0.001) and to 2.2+/-1.2 cm2 at the sixth month (P < 0.001) and LAA ejection fraction: from 41+/-12% to 46+/-10% at the first (P = 0.007) and to 47+/-8% at the sixth month (P = 0.003)]. LAA active emptying and filling flow and pulmonary venous systolic velocities also increased after CRT. The appendage active emptying velocity correlated significantly with left ventricular ejection fraction (r = 0.50, P = 0.002), LAA ejection fraction (r = 0.51, P = 0.002), left atrial maximal volume, LAVmax (r = -0.44, P = 0.007), left atrial minimal volume, LAVmin (r = -0.50, P = 0.002) and pulmonary vein systolic flow velocity (r = 0.33, P = 0.05).

CONCLUSION

Treatment of heart failure by CRT results with marked improvements in LAA function and increases pulmonary venous systolic velocity.

Patients With Atrial Fibrillation and Dense Spontaneous Echo Contrast at High Risk

OBJECTIVES

We sought to assess the prognosis of patients with atrial fibrillation (AF) and dense spontaneous echo contrast (SEC) and to determine the incidence of cerebral embolism under continued oral anticoagulation.

BACKGROUND

Patients with AF and dense SEC have an increased risk of cerebral embolism. However, there is little knowledge about the long-term fate and the rate of clinical silent cerebral embolism under continued oral anticoagulation.

METHODS

Between 1998 and 2001, all consecutive patients with AF and dense SEC were included in the study. We performed serial and prospective transesophageal echocardiography, cranial magnetic resonance imaging, and clinical examinations during a period of 12 months.

RESULTS

A total of 128 patients with dense SEC and AF were included. The control group consisted of 143 patients with faint SEC and AF. During the follow-up period, three patients (2%) had cerebral embolism with neurologic deficits. A total of eight patients (6%) died due to embolic events, and 19 (15%) patients had silent embolism, as documented on cerebral magnetic resonance imaging. Patients with an event had significantly lower left atrial appendage peak emptying velocities and more commonly had a history of previous thromboembolism and denser SEC, as compared with patients without an event.

CONCLUSIONS

Patients with AF and dense SEC have a high likelihood of cerebral embolism (22%) and/or death, despite oral anticoagulation. Low peak emptying velocities of the left atrial appendage and dense SEC are independent predictors of an event.

Percutaneous occlusion of the left atrial appendage for systemic embolism prevention in patients with atrial fibrillation: state of the art and report of two cases

Atrial fibrillation is a benign arrhythmia but it is associated with an elevated thromboembolic risk. The treatment of choice is oral anticoagulation. However not all the patients can benefit from oral anticoagulation, due to bleeding risk or other contraindications. Considering that the most common embolic source in patients with atrial fibrillation is the left atrial appendage, different surgical techniques have been suggested for its closure. For patients at high risk, since August 2001 a device is available for percutaneous occlusion of the left atrial appendage (PLAATO). The PLAATO device consists of a self-expandable nitinol cage with small anchors on its surface to avoid systemic migration. The implantation procedure is performed with local anesthesia. It requires transseptal puncture and the device is delivered to the appendage through a specially designed sheath. The maneuver is performed under transesophageal and fluoroscopic guidance. At present more than 250 patients have been implanted, and the results, as far as the safety and the effectiveness are concerned, are really promising. We report 2 cases of recently successfully implanted at our Center.