Echocardiographic evidence of left atrial abnormality in young patients with lone paroxysmal atrial fibrillation

Patient-specific left atrium contraction quantification associated with atrial fibrillation: A region-based approach

BACKGROUND AND OBJECTIVES

Atrial fibrillation (AF) is a widespread cardiac arrhythmia that significantly impacts heart function. AF disrupts atrial mechanical contraction, leading to irregular, uncoordinated, and slow blood flow inside the atria which favors the formation of clots, primarily within the left atrium (LA). A standardized region-based analysis of the LA is missing, and there is not even any consensus about how to define the LA regions. In this study we propose an automatic approach for regionalizing the LA into segments to provide a comprehensive 3D region-based LA contraction assessment. LA global and regional contraction were quantified in control subjects and in AF patients to describe mechanical abnormalities associated with AF.

METHODS

The proposed automatic approach for LA regionalization was tested in thirteen control subjects and seventeen AF patients. After dividing LA into standard regions, we evaluated the global and regional mechanical function by measuring LA contraction parameters, such as regional volume, global and regional strains, regional wall motion and regional shortening fraction.

RESULTS

LA regionalization was successful in all study subjects. In the AF group compared with control subjects, results showed: a global impairment of LA contraction which appeared more pronounced along radial and circumferential direction; a regional impairment of radial strain which was more pronounced in septal, inferior, and lateral regions suggesting a greater reduction in mechanical efficiency in these regions in comparison to the posterior and anterior ones.

CONCLUSION

An automatic approach for LA regionalization was proposed. The regionalization method was proved to be robust with several LA anatomical variations and able to characterize contraction changes associated with AF.

The effect of coronary slow flow on left atrial structure and function

The coronary slow flow phenomenon (CSFP) is common in coronary angiography, however its impact on left atrial (LA) function is still controversial. This study aims to evaluate the LA structure and function of patients with CSFP using two-dimensional speckle tracking echocardiography (2D-STE). Consecutive patients scheduled for coronary angiography from January 2016 to September 2017 were enrolled in this study. Patients’ demographic data, clinical histories, laboratory and angiographic findings were collected and recorded. Diagnostic criteria for CSFP is based on Beltrame et al. proposed in 2012. Meanwhile 139 patients who have no significant stenosis (≤ 40%) and normal blood flow were selected as control. All patients received an echocardiographic examination 24 h before coronary angiography. LA structure and function were measured with echocardiography and 2D-STE. Our results showed that among the 1,954 patients who had received coronary angiography, 512 patients were included in the analysis after the exclusion criteria was implemented. Of those, 101 patients met the CSFP criteria (5.5%). CSFP is mainly seen in LAD (~ 70%). There was no statistical difference in baseline characteristics between the CSFP group and control group, except for a higher proportion of smokers in the CSFP group (P = 0.001). The percentage of monocytes is an independent risk factor for the occurrence of CSFP (P = 0.036) after binary logistic regression analysis. The LA global longitudinal strain (LA-GLS, represents reservoir functions) decreased and LA strain rate at late diastole (LA-SRa, represents booster function) increased in patients with CSFP compared to the control group (P < 0.05). Correlation test of continuous variables by Pearson test suggested that LA-GLS was negatively correlated with TIMI frame count (TFC). We concluded that the percentage of monocytes is an independent risk factor for the CSFP; the LA reservoir and booster functions were impaired in patients with CSFP; LA-GLS is negatively correlated with TFC.

Biomarkers of Atrial Fibrillation in Hypertension

Background:

Atrial fibrillation (AF) is the most frequently encountered cardiac arrhythmia globally and substantially increases the risk for thromboembolic disease. Albeit, 20% of all cases of AF remain undiagnosed. On the other hand, hypertension amplifies the risk for both AF occurrences through hemodynamic and non-hemodynamic mechanisms and cerebrovascular ischemia. Under this prism, prompt diagnosis of undetected AF in hypertensive patients is of pivotal importance.

Method:

We conducted a review of the literature for studies with biomarkers that could be used in AF diagnosis as well as in predicting the transition of paroxysmal AF to sustained AF, especially in hypertensive patients.

Results:

Potential biomarkers for AF can be broadly categorized into electrophysiological, morphological and molecular markers that reflect the underlying mechanisms of adverse atrial remodeling. We focused on P-wave duration and dispersion as electrophysiological markers, and left atrial (LA) and LA appendage size, atrial fibrosis, left ventricular hypertrophy and aortic stiffness as structural biomarkers, respectively. The heterogeneous group of molecular biomarkers of AF encompasses products of the neurohormonal cascade, including NT-pro BNP, BNP, MR-pro ANP, polymorphisms of the ACE and convertases such as corin and furin. In addition, soluble biomarkers of inflammation (i.e. CRP, IL-6) and fibrosis (i.e. TGF-1 and matrix metalloproteinases) were assessed for predicting AF.

Conclusion:

The reviewed individual biomarkers might be a valuable addition to current diagnostic tools but the ideal candidate is expected to combine multiple indices of atrial remodeling in order to effectively detect both AF and adverse characteristics of high risk patients with hypertension.

Adult Height, Prevalent Coronary Artery Calcium Score, and Incident Cardiovascular Disease Outcomes in a Multiethnic Cohort

We assessed the relationships among adult height, coronary artery calcium (CAC) score, incident atherosclerotic cardiovascular disease (ASCVD) events, and atrial fibrillation (AFib) in a multiethnic cohort. We used race/ethnicity-specific height (dichotomized by median value and in quartiles) as the predictor variable within the 4 racial/ethnic groups in the Multi-Ethnic Study of Atherosclerosis (n = 6,814). After a mean of 10.2 years of follow-up (2000-2012), 556 ASCVD events (8.2%) and 539 AFib events (7.9%) occurred. Adult height was not associated with prevalent CAC score (ln(CAC + 1) or categories). Tall stature (i.e., race/ethnicity-specific height ≥median) had a significant but opposite association with future ASCVD and AFib (hazard ratios were 0.72 (95% confidence interval: 0.56, 0.92) and 1.38 (95% confidence interval: 1.07, 1.79), respectively). We observed a gradient-response but opposite association between quartiles of race/ethnicity-specific height and ASCVD/AFib events in our multivariable models. A formal test of interaction between race/ethnicity-specific height and sex was not significant in the ASCVD model (P = 0.78) but was significant in the AFib model (P = 0.03). Tall stature was associated (in a gradient-response fashion) with reduced risk of ASCVD events and increased risk of AFib. Adult height may signal interactions between genetic and environmental factors and may provide risk information independent of current traditional risk factors and CAC score.

Is Left Atrial Function Affected by Coronary Slow Flow? A Two-dimensional Speckle-Tracking Echocardiographic Study

Background:

The coronary slow flow phenomenon (CSFP) is the slow passage of the angiographic contrast agent to the distal portion of the coronary artery in the absence of significant stenosis. We evaluated the left atrial (LA) function in patients with the CSFP using two-dimensional speckle-tracking echocardiography (2DSTE).

Methods:

The LA function was compared through 2DSTE between 36 patients with the CSFP and 36 participants with a normal coronary flow. The two groups were matched for age, sex, hypertension, diabetes mellitus, and the left ventricular function.

Results:

There were no statistically significant differences between the CSFP group and the control group regarding longitudinal systolic strain, early and late diastolic strains, and the strain rate of the LA myocardium.

Conclusions:

The LA function as evaluated with 2DSTE was not different between the CSFP group and the normal coronary flow group when they were matched for age, sex, hypertension, diabetes, and the left ventricular function.

Cytotoxin-associated gene-A bearing strains of Helicobacter pylori and atrial fibrillation due to ischemic origin: is there a link?

Background Helicobacter pylori CagA

strains could increase the risk for atrial fibrillation in patients with coronary artery disease

Methods

Serological status for H. pylori CagA using enzyme-linked immunosorbent assay, C-reactive protein, total leucocytic count and atrial size were determined in 185 coronary artery disease patients (with and without atrial fibrillation) and 80 healthy subjects (control).

Results CagA

strain showed a higher prevalence in the atrial fibrillation group. Atrial dimension and C-reactive protein (independent predictors of atrial fibrillation) were significantly increased in the CagA seropositive subgroup Conclus ons There is a strong liaison between H. pylori CagA infection and atrial fibrillation in coronary artery disease. Increased C reactive protein and atrial size in atrial fibrillation patients may reflect atrial inflammatory remodeling.

Assessments of pulmonary vein and left atrial anatomical variants in atrial fibrillation patients for catheter ablation with cardiac CT

OBJECTIVES

To provide a road map of pulmonary vein (PV) and left atrial (LA) variants in patients with atrial fibrillation (AF) before catheter ablation procedure using cardiac CT.

METHODS

Cardiac CT was performed in 1420 subjects for accurate anatomical information, including 710 patients with AF and 710 matched controls without AF. PV variants, PV ostia and spatial orientation, LA enlargement, and left atrial diverticulum (LAD) were measured, respectively. Differences between these two groups were also respectively compared. Some risk factors for the occurrence of LAD were analyzed.

RESULTS

In total, PV variants were observed in 202 (28.5 %) patients with AF patients and 206 (29.0 %) controls without AF (p = 0.8153). The ostial sizes of all accessory veins were generally smaller than those of the typical four PVs (p = 0.0153 to 0.3958). There was a significant difference of LA enlargement between the AF and control groups (36.3 % vs. 12.5 %, p < 0.0001), while the prevalence of LAD was similar in these two groups (43.2 % vs. 41.9 %, p = 0.6293).

CONCLUSION

PV variants are common. Detailed knowledge of PVs and LA variants are helpful for providing anatomical road map to determine ablation strategy.

KEY POINTS

• PVs variants are helpful for providing anatomical road map to ablation. • PV variants are common. • DSCT could recognize these anatomic features before ablation as a non-invasive imaging.

Stiff Left Atrial Syndrome: A Complication Undergoing Radiofrequency Catheter Ablation for Atrial Fibrillation

Radiofrequency catheter ablation for atrial fibrillation is an effective approach for treating atrial fibrillation. Its complications have attracted much attention, of which the stiff left atrial syndrome is a recently discovered complication that has not been completely understood. This study aims to investigate the concept, pathologic basis, clinical characteristics, predictors, and treatment protocols of the stiff left atrial syndrome after radiofrequency ablation for atrial fibrillation.

Diagnosing Paroxysmal Atrial Fibrillation in Patients With Ischemic Strokes and Transient Ischemic Attacks Using Echocardiographic Measurements of Left Atrium Function

Twenty-five to 35 percentage of stroke cases are cryptogenic, and it has been demonstrated that paroxysmal atrial fibrillation (AF) is the causal agent in up to 25% of these incidents. The purpose of this study was to investigate if left atrial (LA) parameters have value for diagnosing paroxysmal AF in patients with ischemic stroke (IS) and transient ischemic attack (TIA). We retrospectively analyzed 219 patients who after acute IS or TIA underwent a transthoracic echocardiographic examination. Patients were designated as patients with paroxysmal AF if they had one or more reported incidents of AF before or after their echocardiographic examination. Patients in the paroxysmal AF group were significantly older and had higher CHA2DS2-VASc score than patients without paroxysmal AF (p <0.05 for both). None of the conventional echocardiographic parameters were significantly associated with paroxysmal AF. However, the atrial measurements evaluating LA function (min LA volume and LA emptying fraction) were significantly different (LA emptying fraction: 45% ± 10% vs 50% ± 10%, p = 0.004; minimal LA volume: 30.2 ml ± 17.3 ml vs 24 ml ± 10 ml, p = 0.035 in patients with paroxysmal AF, even after adjustment for age, gender, CHA2DS2-VASc score, and stroke severity [p <0.05 for both]). By combining the cut-off values of age, LA emptying fraction, and minimal LA volume the diagnostic accuracy of paroxysmal AF was improved, resulting in a sensitivity of 95% and negative predictive value of 97%. In conclusion, in patients with IS and TIA, LA function measurements (minimal LA volume and LA emptying fraction) are independently associated with paroxysmal AF and may improve risk stratification for paroxysmal AF presence after IS or TIA.

Diagnosing Paroxysmal Atrial Fibrillation: Are Biomarkers the Solution to This Elusive Arrhythmia?

Atrial fibrillation (AF) is the commonest sustained arrhythmia globally and results in significantly increased morbidity and mortality including a fivefold risk of stroke. Paroxysmal atrial fibrillation (PAF) constitutes approximately half of all AF cases and is thought to represent an early stage of the disease. This intermittent form of atrial arrhythmia can be a challenge to identify and as a result many affected individuals are not prescribed appropriate antithrombotic therapy and hence are at risk of stroke and thromboembolism. Despite these adverse outcomes there have been relatively few diagnostic advances in the field since the introduction of the Holter monitor in 1949. This review aims to establish the available evidence for electrophysiological, molecular, and morphological biomarkers to improve the detection of PAF with reference to the underlying mechanisms for the condition.

Impact of gout on left atrial function: a prospective speckle-tracking echocardiographic study

The purpose of our study was to evaluate the left ventricular (LV) and left atrial (LA) function in patients with gout. A total of 173 patients underwent a comprehensive Doppler-echocardiography examination. Participants were divided into four groups–Stage 0: control (n = 35), Stage I: asymptomatic hyperuricemia (n = 30), Stage II: gouty arthritis without tophi (n = 58), and Stage III: tophaceous gout (n = 50). Serum uric acid levels were not significantly different between stage I, II and III. Stage III patients demonstrated a higher ratio of the transmitral and myocardial peak early diastolic velocities (E/Em) (10.50±3.18 vs. 8.58±2.07; P = 0.008), and larger maximal LA volume index (LAVi) (29.60±9.89 vs. 20.07±4.76 ml/m²; P<0.001) compared with controls. Stage III patients had decreased LV global longitudinal systolic strain (LVε) compared with controls (−20.2±3.06 vs. −21.79±2.27; P = 0.002). Stage III patients also had decreased peak atrial longitudinal strain rate during ventricular systole (ALSR_syst), peak atrial longitudinal strain rate during ventricular early diastole (ALSR_early), and peak atrial longitudinal strain rate during ventricular late diastole (ALSR_late) compared with controls (1.73±0.48 vs. 2.05±0.55 1/s, −1.44±0.53 vs. −2.07±0.84 1/s, −2.07±0.7 vs. −2.66±0.91 1/s, respectively; all P<0.005). Multiple regression analysis revealed severity of gout had an independent negative impact on LA pump function (ALSR_late). In conclusion, gout caused LV diastolic dysfunction, LV subclinical systolic dysfunction and LA reservoir, conduit, and booster pump dysfunction.

Quantification of the functional consequences of atrial fibrillation and surgical ablation on the left atrium using cardiac magnetic resonance imaging

OBJECTIVES

The effect of atrial fibrillation (AF) on left atrial (LA) function has not been well defined and has been largely based on limited echocardiographic evaluation. This study examined the effect of AF and a subsequent Cox-Maze IV (CMIV) procedure on atrial function.

METHODS

Cardiac magnetic resonance imaging (cMRI) was performed in 20 healthy volunteers, 8 patients with paroxysmal atrial fibrillation (PAF) and 7 patients with persistent or long-standing persistent atrial fibrillation (LSP AF). Six of the PAF patients underwent surgical ablation with the CMIV procedure and 5 underwent both pre- and postoperative cMRIs. The persistent or LSP AF patients underwent only postoperative cMRIs because all scans were performed with patients in normal sinus rhythm. Volume-time curves throughout the cardiac cycle and regional wall shortening were evaluated using the cine images and compared across groups.

RESULTS

Compared with normal volunteers, patients with PAF had significantly decreased reservoir contribution to left ventricular (LV) filling (P = 0.0010), an increased conduit function contribution (P = 0.04) and preserved booster pump function (P = 0.14). Following the CMIV procedure, significant reductions were noted with respect to reservoir and booster pump function, with corresponding increases in conduit function. These differences were more drastic in patients with persistent/LSP AF. Regional wall motion was significantly reduced by PAF in all wall segments (P < 0.05), but was not further reduced by the CMIV. Despite changes in LA function, LV function was preserved following surgery.

CONCLUSIONS

PAF significantly altered LA function and has a detrimental effect on regional wall motion. Surgical intervention further altered LA function, but the reasons for this are likely multifactorial and not entirely related to the lesion set itself.

Atrial fibrillation from the pathologist's perspective

Atrial fibrillation (AF), the most common sustained cardiac arrhythmia encountered in clinical practice, is associated with increased morbidity and mortality. Electrophysiologically, it is characterized by a high rate of asynchronous atrial cell depolarization causing a loss of atrial contractile function and irregular ventricular rates. For a long time, AF was considered as a pure functional disorder without any structural background. Only in recent years, have new mapping and imaging techniques identified atrial locations, which are very often involved in the initiation and maintenance of this supraventricular arrhythmia (i.e. the distal portion of the pulmonary veins and the surrounding atrial myocardium). Morphological analysis of these myocardial sites has demonstrated significant structural remodeling as well as paved the way for further knowledge of AF natural history, pathogenesis, and treatment. This architectural myocardial disarrangement is induced by the arrhythmia itself and the very frequently associated cardiovascular disorders. At the same time, the structural remodeling is also capable of sustaining AF, thereby creating a sort of pathogenetic vicious circle. This review focuses on current understanding about the structural and genetic bases of AF with reference to their classification, pathogenesis, and clinical implications.

Left atrial functional remodeling in lone atrial fibrillation: a two-dimensional speckle tracking echocardiographic study

OBJECTIVE

The aim of this study was to assess left atrial (LA) functional remodeling in lone atrial fibrillation (LAF) patients via two-dimensional speckle tracking echocardiography (2DSTE).

METHODS

Forty-five paroxysmal LAF patients and 30 healthy controls underwent 2DSTE in sinus rhythm. Longitudinal LA strain/strain rate (LAS/LASR) of booster, reservoir, and conduit function in apical four- and two-chamber views were measured and averages of the 2 views were used.

RESULTS

The 2 groups had similarity in LA volume. LAS and LASR of the 3 phasic functions were reduced in patients. Comparing the 2 groups, LA booster strain (LASa) and strain rate were -12.31 ± 3.15 versus -15.30 ± 2.52% and -1.64 ± 0.51 versus -2.08 ± 0.48 1/sec, respectively, P < 0.05 for both. Multivariate regression confirmed that LAF was an independent determinant of LAS/LASR reduction. LASa was the most accurate parameter for differentiating LAF patients from controls (area under receiver operating characteristic curve, 0.763; cutoff value, -14.3%; sensitivity, 71.1% and specificity, 70.0%). Finally, LASa decrement was found to be the only significant predictor of early atrial fibrillation (AF) recurrence (odds ratio [OR], 1.39 per unit decrement; 95% CI, 1.02-1.89; P = 0.038).

CONCLUSIONS

Remodeling of LA booster pump, reservoir, and conduit function in LAF patients can be detected by 2DSTE before structural remodeling. Occurrence of LAF is associated with impairment of LA intrinsic myocardial properties. LASa can differentiate LAF patients and lower LASa is associated with early recurrence of AF after ablation.

Left atrial deformation analysis by speckle tracking echocardiography for prediction of cardiovascular outcomes

The incremental value of left atrial (LA) deformation analysis by speckle tracking echocardiography compared with LA volume or LA ejection fraction as a cardiovascular risk marker has not been evaluated prospectively. We sought to compare LA function by speckle tracking echocardiography to other conventional LA parameters for prediction of adverse cardiovascular outcomes. This prospective study included 312 adults (mean age 71 ± 6 years, 56% men) in sinus rhythm who were followed for development of first atrial fibrillation, congestive heart failure, stroke, transient ischemic attack, myocardial infarction, coronary revascularization, and cardiovascular death. Global peak atrial longitudinal strain (PALS) by speckle tracking echocardiography was measured in all subjects by averaging all atrial segments. Left atrium was assessed with biplane LA volume, LA ejection fraction, 4-chamber LA area, and M-mode dimension. Of 312 subjects at baseline, 43 had 61 new events during a mean follow-up of 3.1 ± 1.4 years. All LA parameters, traditional parameters, and parameters derived by speckle tracking echocardiography were independently predictive of combined outcomes (p <0.0001 for all comparisons). Overall performance for prediction of cardiovascular events was greatest for global PALS (area under receiver operator characteristic curve: global PALS 0.83, indexed LA volume 0.71, LA ejection fraction 0.69, LA area 0.64, LA diameter 0.59). A graded association between degree of LA enlargement and risk of cardiovascular events was evident only for global PALS and indexed LA volume. In conclusion, global PALS is a strong and independent predictor of cardiovascular events and appears to be superior to conventional parameters of LA analysis.

Novel echocardiographic techniques to assess left atrial size, anatomy and function

Three-dimensional echocardiography (3DE) and speckle tracking echocardiography (STE) have recently applied as imaging techniques to accurately evaluate left atrial (LA) size, anatomy and function. 3DE and off-line quantification softwares, have allowed, in comparison to magnetic resonance imaging, the most time-efficient and accurate method of LA volume quantification. STE provides a non-Doppler, angle-independent and objective quantification of LA myocardial deformation. Data regarding feasibility, accuracy and clinical applications of LA analysis by 3DE and STE are rapidly gathering. This review describes the fundamental concepts of LA 3DE and STE, illustrates how to obtain respective measurements and discuss their recognized and emerging clinical applications.

QRS duration is associated with atrial fibrillation in patients with left ventricular dysfunction

BACKGROUND

QRSduration (QRSd) is associated with higher mortality and morbidity in patients with left ventricular (LV) dysfunction. The association between QRSd and atrial fibrillation (AF) has not been studied in this patient population.

OBJECTIVES

To investigate the association between QRSd and AF in patients with LV dysfunction.

METHODS

Data were obtained from the National Registry to Advance Heart Health (ADVANCENT) registry, a prospective multicenter registry of patients with left ventricular ejection fraction (LVEF) < or = 40%. A total of 25 268 patients from 106 centers in the United States, were enrolled between June 2003 and November 2004. Demographic and clinical characteristics of patients were collected from interviews and medical records.

RESULTS

: Mean age was 66.3+/-13 years, 71.5% were males, and 81.9% were white. A total of 14 452 (57.8%) patients had a QRSd < 120 ms, 5304 (21.2%) had a QRSd between 120 and 150 ms, and 5269 (21%) had a QRSd > 150 ms. Atrial fibrillation occurred in 20.9%, 27.5%, and 35.5% of patients in the QRS groups, respectively (P < 0.0001). After adjusting for potential AF risk factors (age, gender, race, body mass index, hypertension, diabetes, renal failure, cancer, lung disease, New York Heart Association [NYHA] class, ejection fraction, etiology of cardiomyopathy) and the use of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, and lipid lowering drugs, QRS duration remained independently associated with AF (odds ratio: 1.20, 95% confidence interval: 1.14-1.25).

CONCLUSION

In this large cohort of patients, QRSd was strongly associated with AF and therefore may predict the occurrence of this arrhythmia in patients with LV dysfunction. This association persisted after adjusting for disease severity, comorbid conditions, and the use of medications known to be protective against AF.

Prognostic implications of left atrial dilation evaluated by echocardiographic volume in patients with normal left atrial antero-posterior dimensions

BACKGROUND

The purpose of this study was to clarify the clinical characteristics and prognostic implications of left atrial (LA) dilation evaluated echocardiographic volume in patients with normal LA dimension (LAD).

METHODS

A total of 140 consecutive patients (81 men, mean age: 57 ± 18 years) with normal LAD (<39 mm for women and <41 mm for men) who underwent conventional echocardiography and tissue Doppler imaging were enrolled. LA volume (LAV) ≥29 ml/m(2) was defined as abnormal LAV. Hospitalization for heart failure (HF) and cardiac death were defined as cardiac events.

RESULTS

Eighty-seven (62%) of the patients had LA dilation, defined as a normal LAD but an abnormal LAV. Patients with LA dilation were significantly older and had a significantly higher left ventricular (LV) mass index (LVMI) and incidences of hypertension and HF than did patients with both normal LAD and normal LAV. Logistic regression analysis revealed that increased LVMI was an independent (p < 0.01) determinant of LA dilatation. During a follow-up period of 16 ± 10 months, ten patients had cardiac events. Patients with cardiac events had a higher incidence of LA dilation than those without cardiac events (100 vs. 59%, p < 0.05). A Kaplan-Meier survival curve showed that patients with LA dilation had a significantly lower survival rate than those with both normal LAD and normal LAV (log rank 6.1, p = 0.014).

CONCLUSIONS

LV hypertrophy is an independent determinant of LA dilation in patients with normal LAD. Assessment of LA morphology using LAV can contribute to risk stratification in patients with normal LAD.

Atrial fibrosis and atrial fibrillation: the role of the TGF-β1 signaling pathway

BACKGROUND

Atrial fibrosis concurs with chronic atrial fibrillation (AF), a phenomenon that contributes to the resistance to restore and maintain sinus rhythm (SR). Fibrogenesis represents a complex process in which the transforming growth factor-β1 (TGF-β1) pathway may play a major role, e.g. in the setting of myocardial infarction. The present study addresses the potential contribution of the TGF-β1 signaling pathway to atrial fibrosis in patients with AF.

METHODS AND RESULTS

Right atrial appendages of 163 patients were excised during heart surgery and grouped according to rhythm (SR vs. AF) and AF duration. Five groups were defined: SR, paroxysmal/chronic persistent AF (<6 months), chronic permanent AF (CAF) of 7-24 months, 25-60 months, and >60 months duration. Collagen content of atria, determined morphometrically, revealed a steady and significant increase in patients with SR (14.6±8.9%) up to patients with CAF of >60 months (28.1±7.1%). Likewise, expression of TGF-β1 mRNA and protein, TGF-β-receptor-II protein, profibrotic phospho-Smad-2 and -4 proteins increased. However, the TGF-β(1) effect appeared to decline with increasing AF duration, characterized by a decrease in TGF-β-receptor-I protein, increases of TGF-β inhibiting Smad-7 protein and a reduction of ph-Smad-2.

CONCLUSIONS

Human atrial fibrogenesis in patients with atrial fibrillation is accompanied by a biphasic response, an early increase and later loss of responsiveness to TGF-β(1). It appears that fibrosis progresses despite compensatory changes in the TGF-β-signaling pathway. The sequential changes in the contribution of different profibrotic processes during the establishment of AF may offer the opportunity to selectively interfere with the atrial remodeling process at different stages.

Physical activity, height, and left atrial size are independent risk factors for lone atrial fibrillation in middle-aged healthy individuals

AIMS

The aetiology of atrial fibrillation (AF) remains unknown in some patients. The aim of the study was to identify new risk factors for developing lone AF (LAF).

METHODS AND RESULTS

A series of 107 consecutive patients younger than 65, seen in the emergency room for an episode of LAF of <48 h duration were included in the study. A group of 107 healthy volunteers matched for age and sex were recruited as controls. All subjects answered a validated questionnaire concerning leisure and occupational activities performed throughout their lifetimes to estimate accumulated hours of physical effort, classified in four levels of intensity. Demographic and echocardiographic measurements were also recorded. There were 69% of males and mean age was 48 +/- 11 years. AF was paroxysmal in 57% and persistent in the remaining 43%. Patients with AF performed more hours of both moderate and heavy intensity physical activity. They also were taller, and had a larger left atria, ventricle, and body surface area. At the multivariable analysis, only moderate and heavy physical activity, height, and anteroposterior atrial diameter were independently associated with LAF.

CONCLUSIONS

Accumulated lifetime physical activity, height, and left atrial size are risk factors for LAF in healthy middle-aged individuals.

Left atrial enlargement as a predictor of recurrences in lone paroxysmal atrial fibrillation

BACKGROUND

A mild increase in left atrial (LA) size predicts arrhythmia onset and adverse events in patients with lone paroxysmal atrial fibrillation (LPAF). However, the role of LA size as a predictor of LPAF recurrences is still controversial.

OBJECTIVE

The potential role of LA size in affecting the frequency of recurrent episodes in patients with LPAF was investigated.

METHODS

Fifty-one patients who were admitted for a first episode of LPAF and presenting with one recurrence (group A, n=20), two or three recurrences (group B, n=18), or four or more recurrences (group C, n=13) during an average follow-up period of two years were retrospectively selected. The M-mode LA anteroposterior diameter (LAAPd) was used as an echocardiographic surrogate of LA size.

RESULTS

At baseline, LA size was normal or borderline in the control group, group A and group B, but significantly increased in group C. At two years' follow-up, a significant further LA enlargement from baseline was observed in group B (LAAPd 40+/-1.1 mm versus 40.7+/-1.2 mm, P<0.01) and in group C (LAAPd 41.4+/-1.6 mm versus 42.7+/-1.7 mm, P<0.001), while LA size remained substantially unchanged in the control group and in group A.

CONCLUSIONS

Observations confirmed the association of increased LA size and LPAF onset, and provide the first evidence for a potential role of LA progressive enlargement as a predictor of arrhythmic recurrences.

Cardiovascular Imaging in the Management of Atrial Fibrillation

Atrial fibrillation (AF) is he most commonly encountered arrhythmia in clinical practice, with an overall prevalence of 0.4% in the general population. Recent advances in technology and in the understanding of the pathophysiology of AF have led to more definitive and potentially curative therapeutic approaches. Echocardiography has a well-established role in the assessment of cardiac structure and function and risk stratification, and has become an essential part of the guidelines for management of AF. The development of intracardiac echocardiography has led to real-time guidance of percutaneous interventions, including radiofrequency ablation and left atrial appendage closure procedures for patients with AF. Other imaging modalities, including computed tomography and magnetic resonance angiography, have allowed for more accurate measurement and better understanding of the cardiac anatomy. We review the impact of various imaging modalities in the evaluation and management of AF.

Lone atrial fibrillation: Pathologic or not?

Atrial fibrillation risk has been strongly associated with increasing age and visceral obesity. These characteristics are strongly associated with diabetes, decreased heart rate variability, and chronic inflammation. Lone atrial fibrillation (LAF) on the other hand exhibits a predilection for the physically fit and the middle aged, especially males. Given these opposing features it is postulated that pathologic AF is due to cardiac fibrosis and other age related changes while LAF is due to physiologic neurohormonal changes related to autonomic tone, insulin sensitivity, and electrolyte imbalance and that pathologic AF and LAF can be reliably differentiated via an anthropometric approach using weight, height, hip, and waist measurements. An anthropometric study is undertaken from an LAF database to test this hypothesis. Such individuals in addition to being younger and predominantly male appear to be taller with less central adiposity vs. those with pathologic AF. The ramifications of these findings with respect to insulin resistance, sympathetic tone, inflammation and hypertension, often associated with pathologic atrial fibrillation, are discussed. Speculation is drawn about possible etiologic link with mitral valve prolapse, which is commonly encountered in the tall and thin and which shares multiple clinical features with LAF.

What Is the Best Approach for the Assessment of Left Atrial Size? Comparison of Various Unidimensional and Two-dimensional Parameters with Three-dimensional Echocardiographically Determined Left Atrial Volume

BACKGROUND

Left atrial (LA) size has prognostic importance in a variety of cardiac conditions. Diameters, area, or volume derived from 2-dimensional (2D) echocardiography (2DE) are commonly used to measure LA size, but involve numerous assumptions. This study examined the accuracy of these 2DE parameters compared to 3-dimensional echocardiographic LA volume (3DV).

METHODS

LA diameters, area, and volume measured from 2DE were correlated with 3DV in 118 patients with dilated cardiomyopathy, hypertrophic cardiomyopathy, or without structural heart disease.

RESULTS

Diameter (anterior-posterior, superior-inferior, and medial-lateral) and 2DE area measurements had statistically significant, but modest, correlations with 3DV, and exhibited a large degree of scatter in comparison with 3DV. The 2DE-derived volume had an excellent correlation with 3DV, but consistently underestimated LA volume.

CONCLUSION

The 2DE LA volume correlates better than other parameters with 3DV, but often results in underestimation. Thus, caution should be exercised when using unidimensional and 2D measurements of LA size.