Left atrial function and ventricular filling in hypertensive patients with paroxysmal atrial fibrillation

Biomarkers of Metabolic Syndrome: Role in Pathogenesis and Pathophysiology Of Atrial Fibrillation

The relationship between Metabolic syndrome and Atrial Fibrillation is confirmed by many studies. The components of Metabolic syndrome cause remodeling of the atrial. Metabolic syndrome and metabolic derangements of the syndrome could be the cause of the pathogenesis of AF. This review article discusses the major biomarkers of Metabolic syndrome and their role in the pathogenesis of AF. The biomarkers are adiponectin, leptin, Leptin/ Adiponectin ratio, TNF-α, Interleukin-6, Interleukin-10, PTX3, ghrelin, uric acid, and OxLDL.The elevated plasma levels of adiponectin were linked to the presence of persistent AF. Leptin signaling contributes to angiotensin-II evoked AF and atrial fibrosis. Tumor necrosis factor-alpha involvement has been shown in the pathogenesis of chronic AF. Similarly, Valvular AF patients showed high levels of TNF-α. Increased left atrial size was associated with the interleukin-6 because it is a well-known risk factor for AF. Interleukin-10 as well as TNF-α were linked to AF recurrence after catheter ablation. PTX3 could be superior to other inflammatory markers that were reported to be elevated in AF. The serum ghrelin concentration in AF patients was reduced and significantly increased after treatment. Elevated levels of uric acid could be related to the burden of AF. Increased OxLDL was found in AF as compared to sinus rhythm control.

Reduced nNOS activity is responsible for impaired fatty acid-dependent mitochondrial oxygen consumption in atrial myocardium from hypertensive rat

Fatty acid (FA)-dependent mitochondrial activities of atrial myocardium in hypertension (HTN) and its regulation by nitric oxide (NO) remain unidentified. Here, we have studied palmitic acid (PA) regulation of cardiac mitochondrial oxygen consumption rate (OCR) in left atrial (LA) myocardium of sham and angiotensin II-induced HTN rats and their regulations by endothelial NO synthase (eNOS) and neuronal NO synthase (nNOS). The effects were compared with those of left ventricular (LV) myocytes. Our results showed that OCR was greater in HTN-LA compared with that in sham-LA. PA increased OCR in sham-LA, sham-LV, and HTN-LV but reduced it in HTN-LA. Inhibition of nNOS (S-methyl-L-thiocitrulline, SMTC) or eNOS/nNOS (Nω-nitro-L-arginine methyl ester hydrochloride, L-NAME) reduced PA increment of OCR in sham-LA but exerted no effect on OCR in HTN-LA. SMTC reduced OCR in HTN-LV and L-NAME reduced OCR in sham-LV. nNOS was the predominant source of NO in LA and LV. nNOS-derived NO was increased in HTN-LA and HTN-LV. PA reduced eNOS^Ser1177, nNOS^Ser1417, and NO level in HTN-LA but exerted no effect in sham-LA. In contrast, PA increased NO in HTN-LV and enhanced nNOS^Ser1417 but reduced NO level in sham-LV without affecting eNOS^Ser1177, eNOS^Thr495, or nNOS^Ser1417. 2-Bromopalmitate (2BP), which blocks the S-palmitoylation of target proteins, prevented PA-dependent decrease of nNOS^Ser1417 and OCR in HTN-LA. In HTN-LV, 2BP prevented PA-induced OCR without affecting nNOS^Ser1417. Our results reveal that FA-induced mitochondrial activity in atrial myocardium is impaired in HTN which is mediated by reduced nNOS activity and NO bioavailability. Metabolic dysregulation may underlie diastolic dysfunction of atrial myocardium in HTN.

The extent of complex fractionated atrial electrograms in the left atrium reflects age-related electrical remodeling in patients with persistent atrial fibrillation

BACKGROUNDS

Alterations in the atrial structure and function associated with aging result in electric remodeling of the left atrium (LA) in patients with persistent atrial fibrillation (AF). We performed this study to evaluate the influence of age on electric remodeling as assessed by the extent of complex fractionated atrial electrograms (CFAEs) in the LA.

METHODS

A total of 122 patients (mean age, 55.9 ± 10.4 years; range, 31-79; 106 males) who underwent catheter ablation for drug-refractory persistent AF were included in the study. The extent of CFAE was measured by CFAE area and its index (CFAE area/LA surface area × 100) using three-dimensional automated software of NavX system.

RESULTS

The mean value of CFAE extent was significantly different among age groups; the CFAE area decreased significantly with increasing age (30 seconds [43.2 ± 14.5 mm2] vs 40 seconds [28.6 ± 6.0 mm2] vs 50 seconds [22.8 ± 3.4 mm2] vs 60 seconds [15.3 ± 2.6 mm2] vs 70 seconds [10.3 ± 3.2 mm2]; P = .010). A similar significant decrease was observed in the CFAE area index (30 seconds [22.9 ± 7.4] vs 40 seconds [14.9 ± 3.4] vs 50 seconds [10.4 ± 1.6] vs 60 seconds [6.9 ± 1.2] vs 70 seconds [4.6 ± 1.4]; P = .002). Age had a significantly negative correlation with the CFAE area (r = -0.322, P < .001) and CFAE area index (r = -0.357, P < .001).

CONCLUSIONS

Increasing age is associated with electric remodeling in the LA characterized by a decrease in the extent of CFAE area and its index.

Clinical implication of disturbed left atrial phasic functions in the heterogeneous population associated with hypertension or atrial fibrillation

BACKGROUND

To evaluate left atrial (LA) phasic functions in patients with hypertension and/or paroxysmal atrial fibrillation (PAF) and its clinical significance.

METHODS

LA strain was studied in 77 patients (25 hypertension, 24 lone AF, and 28 with both hypertension and PAF) and 28 controls using two-dimensional speckle-tracking echocardiography (2D STE). The following indexes during atrial reservoir, conduit and pump phase were analyzed respectively: (1) peak atrial longitudinal strain (PALS) and strain rate (PALSR), (2) the standard deviation of time to PALS and PALSR of all LA segments (TpS-SD% and TpSR-SD%).

RESULTS

Compared with controls, PALS_res, PALS_cond and PALSR_cond were significantly reduced in patients with isolated hypertension (all P < 0.01) but no significant differences were observed in PALS_pump, PALSR_pump and TpS_pump-SD% between them (all P > 0.05). PALS_pump, PALSR_pump and PALSR_res were significantly lower in patients with both hypertension and PAF than in those with isolated hypertension (all P < 0.05). PALS and PALSR were significantly decreased, and TpS-SD% was significantly increased during each phase in lone AF patients than in controls (all P < 0.05), and PALSR_pump was further depressed in patients with both hypertension and PAF (P = 0.029). PALSR_cond ≤ 1.475 s^- 1 combined with TpS_pump-SD% ≥ 3.25% (sensitivity, 85%; specificity, 71%; AUC = 0.845, P < 0.001) could distinguish lone AF from healthy subjects effectively, while in hypertensive patients, PALS_pump ≤ 14.2% was found to be an independent differentiator for occurrence of AF or not with sensitivity of 81% and specificity of 84% (AUC = 0.838, P < 0.001). LAVI≥29.3 mL/m² was an independent characteristic for reflecting different LA remodeling in lone AF or hypertension with AF.

CONCLUSIONS

The impairment of LA phasic functions was varied in patients with hypertension and/or AF. The disturbed LA phasic functions were proved to have independent abilities of differential diagnosis in this heterogeneous population associated with hypertension or AF.

Inhibition of renin-angiotensin axis reduces the risk of thrombus formation in the left atrial appendage in patients with hypertension complicated by atrial fibrillation

Aims:

We examined whether the use of a renin-angiotensin-aldosterone system (RAS) inhibitor plays a role in protecting against left atrial appendage thrombus (LAAT) in patients with hypertension complicated by atrial fibrillation (AF).

Methods:

Two observational studies were conducted on patients with diagnoses of hypertension and AF, who were categorized into RAS inhibitor user or nonuser groups. Demographic characteristics, clinical characteristics, echocardiographic parameters and hemostatic markers were examined and the occurrence of LAAT during follow-up were recorded.

Results:

In the first study (n = 131), LA peak systolic strain and LAA emptying flow velocity (LAA eV) were significantly increased in patients on RAS inhibitors compared with the nonuser group (p < 0.05). Lower D-dimer and fibrinogen levels were observed in patients on RAS inhibitors (p < 0.05). In the second study (n = 99), 25.9% (n = 11) of patients on RAS inhibitors developed LAAT, compared with 46.7% (n = 21) in the nonuser group (p < 0.05). After controlling for risk factors related to LAAT, use of RAS inhibitors remained associated with a significantly lower risk of developing LAAT (HR, 0.406; 95% CI, 0.191–0.862; p = 0.019).

Conclusions:

RAS inhibitors use was associated with a significant reduction in the risk of LAAT in patients with hypertension and AF.

Role of atrial wall thickness in wave-dynamics of atrial fibrillation

Background/Aims

Atrial anatomy and thickness may affect the electrical wave-dynamics of atrial fibrillation (AF). We explored the relationship between left atrial (LA) wall thickness (LAWT) or LA geometry and AF wave-dynamics.

Methods

We included 15 patients with persistent AF (age, 62.3 ± 11.9 years) who underwent AF catheter ablation. We measured the LAWT, LA endocardial curvature, and SD-curvature (surface bumpiness) from preprocedural computed tomography images. We compared those anatomical characteristics with electrophysiologic parameters such as dominant frequency (DF), Shannon entropy (ShEn), or complex fractionated atrial electrogram (CFAE)-cycle length (CL), calculated from intracardiac bipolar electrograms (300–500 points, 5 s), acquired during ablation procedures.

Results

1. LAWT (excluding fat) varied widely among patients, locations, and types of AF. LAWT was inversely correlated with LA volume (r = -0.565, p = 0.028) and positively correlated with SD-curvature (r = 0.272, p < 0.001). 2. LAWT was positively correlated with ShEn (r = 0.233, p < 0.001) and negatively correlated with CFAE-CL (r = -0.107, p = 0.038). 3. In the multivariate linear regression analyses for AF wave-dynamics parameters, DF (β = -0.29 [95% CI -0.44–-0.14], p < 0.001), ShEn (β = 0.19 [95% CI 0.12–0.25], p < 0.001), and CFAE-CL (β = 7.49 [95% CI 0.65–14.34], p = 0.032) were independently associated with LAWT.

Conclusion

Regional LAWT is associated with LA structural features, and has significant correlations with the wave-dynamics parameters associated with electrical wavebreaks or rotors in patients with persistent AF.

Peak Early Diastolic Transmitral Velocity As A Surrogate Marker Of Short-Term Atrial Fibrillation Recurrence After Electrical Cardioversion

OBJECTIVES

The aim of this study was to assess if peak early diastolic transmitral velocity (E-wave) can be used as a surrogate marker of short-term atrial fibrillation (AF) recurrence.

METHODS

We prospectively studied 57 consecutive patients who underwent electrical cardioversion (ECV) for AF and successfully converted to sinus rhythm. N-terminal brain natriuretic peptide levels (BNP) before and after ECV was measured in all patients. The follow-up included physical examination and a 12-lead electrocardiogram 14 days and one month after the ECV.

RESULTS

In 42.1% patients AF recurred during one-month follow-up period. Gender, presence of mitral regurgitation, treatment with angiotensin II receptor blocker and left atrium diameter independently influenced E-wave velocity before ECV. E-wave velocity fell immediately after successful ECV (94.0±27 cm/s vs 79.7±23 cm/s, P<0.0001). E-wave velocity before ECV>94 cm/s and E-wave velocity after ECV >80 cm/s were predictors of one-month AF recurrence [(Hazard Ratio) HR=3.62 with 95% CI=1.49-8.78 and HR=3.76 with 95% CI=1.40-10.10, respectively]. E-wave velocity before and E-wave velocity after ECV remained predictors of AF recurrence but only in non-hypertensive patients (HR=1.01 with 95% C.I=1.01-1.03 and HR=1.03 with 95% C.I=1.01-1.06, respectively). Similarly, BNP levels before and after ECV were associated with an increased the risk of AF recurrence (HR=1.14 with 95% C.I 1.01-1.28 and HR= 1.16 with 95% C.I 1.03- 1.31, respectively). The addition of BNP levels to E-wave velocity before ECV appeared to have incremental value on short-term AF recurrence but at a marginally statistical significance (LR chi2=3.28, p=0.07).

CONCLUSIONS

E-wave velocity before and after ECV appears to be a marker of short-term recurrence of AF.

Comparison of Prolonged Atrial Electromechanical Delays with Different Definitions in the Discrimination of Patients with Non-Valvular Paroxysmal Atrial Fibrillation

Background and Objectives

Previous studies have evaluated atrial electromechanical delays (AEMDs) with a number of different definitions to discriminate patients with paroxysmal atrial fibrillation (PAF) from controls without PAF. However, their discriminative values for PAF have not previously been directly compared.

Subjects and Methods

A total of 65 PAF patients and 130 control subjects matched for age, sex, history of hypertension, and diabetes mellitus were selected. The AEMDi and AEMDp were defined as the time intervals from the initiation of the P wave on the surface electrocardiogram to the initiation and peak of the late diastolic transmitral inflow on pulsed wave Doppler images, respectively. The AEMDim and AEMDpm were defined as the time intervals from the initiation of the P wave on the surface electrocardiogram to the initiation and peak of the late diastolic lateral mitral annular motion on tissue Doppler images, respectively.

Results

There were no significant differences in the clinical characteristics between the two groups. All 4 AEMDs were consistently longer in the PAF group, and proven effective to differentiate the PAF patients from the controls. The AEMDi measurement had a larger area under the curve (AUC) than the other AEMDs, left atrial volume index, and P wave amplitude. However, the AEMDp, AEMDim, and AEMDpm measurements had AUCs similar to those of the left atrial volume index and P wave amplitude.

Conclusion

The findings suggest that the AEMDi is better than the other AEMDs for the discrimination of PAF patients from the controls.

Comparison of Characteristics and Outcomes of Dabigatran Versus Warfarin in Hypertensive Patients With Atrial Fibrillation (from the RE-LY Trial)

Hypertension is frequent in patients with atrial fibrillation (AF) and is an independent risk factor for stroke. The Randomized Evaluation of Long Term Anticoagulant TherapY (RE-LY) trial found dabigatran 110 mg (D110) and 150 mg twice daily (D150) noninferior or superior to warfarin for stroke reduction in patients with AF, with either a reduction (D110) or similar rates (D150) of major bleeding. Baseline characteristics and outcomes were compared in patients with and without hypertension. The quality of blood pressure control was also assessed. In RE-LY, 14,283 patients (78.9%) had hypertension. The mean blood pressure at baseline was 132.6 ± 17.6/77.7 ± 10.6 and 124.8 ± 16.7/74.6 ± 10.0 mm Hg for patients with and without hypertension, respectively. More patients with hypertension were diabetic (25.6% vs 14.8%, p <0.001), women (38.6% vs 28.3%, p <0.001), and had greater CHADS2 (2.3 vs 1.4, p <0.001) and CHA2DS2-VASc scores (3.8 vs 2.8, p <0.001). Mean blood pressure in all treatment arms in hypertensive patients was similar (130 ± 18/76 ± 11 mm Hg) during the trial. The efficacy and safety of D110 and D150 compared to warfarin were similar (p = nonsignificant) in hypertensive (stroke/systemic embolism rate of 1.47%, 1.20%, and 1.81% and major bleed rate of 2.89%, 3.70%, and 3.69% in the D110, D150, and W, respectively) and normotensive patients (stroke/systemic embolism rate of 1.79%, 0.78%, and 1.36% and major bleed rate of 2.84%, 2.37%, and 3.03% per year in the D110, D150, and W, respectively). Hypertensive patients had more major bleeds (3.39% vs 2.76%; p = 0.007). Intracranial bleeds were similar (0.47% vs 0.31%; p = 0.12). In conclusion, patients with hypertension in RE-LY were more likely female, diabetic, with a greater CHADS2 and CHA2DS2-VASc scores. Blood pressure control in RE-LY was excellent. The benefits of dabigatran over warfarin, including a substantial reduction of intracranial hemorrhage, were similar in both hypertensive and non-hypertensive patients.

Neurovascular Control and Cardiac Structure in Amateur Runners with Hypertension

PURPOSE

The neurovascular mechanisms underlying hypertension are minimized by exercise training. However, it is not known whether previously trained individuals with hypertension would have deleterious repercussion of this disease. Our aim was to investigate the neurovascular control and the cardiac structure of athletes with hypertension.

METHODS

Muscle sympathetic nerve activity (MSNA) (microneurography), baroreflex sensitivity (intravenous infusion of phenylephrine and nitroprusside), arterial stiffness (pulse wave velocity and echotracking), and cardiac structure (echocardiography) were evaluated in 17 runners with hypertension (42 ± 1 yr) and 20 normotensive (43 ± 1 yr) amateur runners.

RESULTS

Runners with hypertension had higher MSNA (+24% burst frequency, P = 0.02; +24%, burst incidence, P < 0.01), left ventricular mass (+22%, P < 0.01), septum wall thickness (+9%, P = 0.04), posterior wall thickness (+11%, P = 0.04), and left atrium (+11%, P < 0.001) compared with normotensive runners. Baroreflex control of heart rate was lower in runners with hypertension during increase (P = 0.05) but not during decrease (P = 0.11) of systolic blood pressure when compared with normotensive runners. There was no difference between groups in baroreflex control of MSNA during increase (P = 0.38) and decrease (P = 0.36) of diastolic blood pressure. Pulse wave velocity (P = 0.71) and carotid variables: intima media thickness (P = 0.18), diameter (P = 0.09), and distension (P = 0.79) were similar between groups.

CONCLUSIONS

Sympathetic overactivity seems to be involved in the underlying mechanisms of hypertension in amateur runners. Alterations in cardiac structure and decreased baroreflex control of heart rate suggest limited protection from exercise training. However, baroreflex control of MSNA and elastic properties of artery are preserved in this population.

Left atrium by echocardiography in clinical practice: from conventional methods to new echocardiographic techniques

Although often referred to as “the forgotten chamber”, compared with left ventricle (LV), especially in the past years, the left atrium (LA) plays a critical role in the clinical expression and prognosis of patients with heart and cerebrovascular disease, as demonstrated by several studies. Echocardiographers initially focused on early detection of atrial geometrical abnormalities through monodimensional atrial diameter quantification and then bidimensional (2D) areas and volume estimation. Now, together with conventional echocardiographic parameters, new echocardiographic techniques, such as strain Doppler, 2D speckle tracking and three-dimensional (3D) echocardiography, allow assessing early LA dysfunction and they all play a fundamental role to detect early functional remodelling before anatomical alterations occur. LA dysfunction and its important prognostic implications may be detected sooner by LA strain than by volumetric measurements.

Disturbed Left Atrial Function is Associated with Paroxysmal Atrial Fibrillation in Hypertension

BACKGROUND

Hypertension is the most prevalent and modifiable risk factor for atrial fibrillation. The pressure overload in the left atrium induces pathophysiological changes leading to alterations in contractile function and electrical properties.

OBJECTIVE

In this study our aim was to assess left atrial function in hypertensive patients to determine the association between left atrial function with paroxysmal atrial fibrillation (PAF).

METHOD

We studied 57 hypertensive patients (age: 53 ± 4 years; left ventricular ejection fraction: 76 ± 6.7%), including 30 consecutive patients with PAF and 30 age-matched control subjects. Left atrial (LA) volumes were measured using the modified Simpson's biplane method. Three types of LA volume were determined: maximal LA(LAVmax), preatrial contraction LA(LAVpreA) and minimal LA volume(LAVmin). LA emptying functions were calculated. LA total emptying volume = LAVmax-LAVmin and the LA total EF = (LAVmax-LAVmin )/LAVmax, LA passive emptying volume = LAVmax- LAVpreA and the LA passive EF = (LAVmax-LAVpreA)/LAVmax, LA active emptying volume = LAVpreA-LAVmin and LA active EF = (LAVpreA-LAVmin )/LAVpreA.

RESULTS

The hypertensive period is longer in hypertensive group with PAF. LAVmax significantly increased in hypertensive group with PAF when compared to hypertensive group without PAF (p=0.010). LAAEF was significantly decreased in hypertensive group with PAF as compared to hypertensive group without PAF (p=0.020). A' was decreased in the hypertensive group with PAF when compared to those without PAF (p = 0.044).

CONCLUSION

Increased LA volume and impaired LA active emptying function was associated with PAF in untreated hypertensive patients. Longer hypertensive period is associated with PAF.

Structural and Functional Remodeling of the Left Atrium: Clinical and Therapeutic Implications for Atrial Fibrillation

Atrial fibrillation (AF) is the most commonly encountered arrhythmia in clinical practice. Despite advances in our understanding of the pathophysiology of this complex arrhythmia, current therapeutic options remain suboptimal. This review aimed to delineate the atrial structural and functional remodeling leading to the perpetuation of AF. We explored the complex changes seen in the atria in various substrates for AF and the therapeutic options available to prevent these changes or for reverse remodeling. Here we also highlighted the emerging role of aggressive risk factor management aimed at the arrhythmogenic atrial substrate to prevent or retard AF progression.

Left atrial function assessed by Doppler echocardiography rather than left atrial volume predicts recurrence in patients with paroxysmal atrial fibrillation

BACKGROUND

Paroxysmal atrial fibrillation (PaAF) may present as a single self-terminating episode of atrial fibrillation (AF) or a more persistent form after sinus conversion. We investigated predictors of recurrence in patients with PaAF.

HYPOTHESIS

Left atrial function would be an useful parameter for predicting PaAF recurrence.

METHODS

The study population included 228 PaAF patients (131 males, age 64±14 years) who underwent transthoracic echocardiography immediately after spontaneous sinus conversion at initial AF diagnosis. We followed the study patients for AF recurrence.

RESULTS

AF recurrence was demonstrated in 45 patients (20%, age 68±13 years) after spontaneous sinus conversion. Patients with recurrence had larger left atrial volume index (32±12 vs 25±10 mL/m2, P<0.001), left ventricle mass index (107±34 vs 93±25 g/m2, P=0.012), and left ventricle filling pressure (E/e'') (14±7 vs 12±5, P=0.012), whereas early diastolic mitral annular velocity (e') (5±2 vs 6±3 cm/s, P=0.021), late diastolic mitral annular velocity (A') (7±3 vs 9±2 cm/s, P<0.001), and peak systolic mitral annular velocity (7±2 vs 8±2 cm/s, P=0.045) were significantly lower. In multivariate Cox regression analysis detecting independent predictors of PaAF recurrence, lower A' (hazard ratio: 0.623, 95% confidence interval: 0.476-0.815, P=0.001) was a significant predictor of AF recurrence.

CONCLUSIONS

A', which indicates left atrial (LA) contractile function after sinus conversion, was the independent predictor of PaAF recurrence, whereas LA volume was not. LA function may be more important than LA volume in predicting recurrence particularly in patients with PaAF.

Hypertension accelerates the 'normal' aging process with a premature increase in left atrial volume

Hypertension (HT) is associated with left ventricular (LV) diastolic dysfunction and consequent left atrial (LA) dilatation. We investigated changes in LA size and phasic function by decade in patients with HT. Patients with mild or moderate HT (n = 122) were compared with a case controlled normal cohort (blood pressure <140/90 mm Hg). Biplane LA maximum, minimum, and pre 'a' wave volumes were measured; LA filling, passive emptying, and active emptying volumes and fractions were calculated. Transmitral inflow and pulsed wave mitral annular tissue Doppler velocity were measured as expressions of LV diastolic function. The HT group had larger LA maximum volumes compared with normal controls for all decades until the 8th decade. Subjects with HT in decade 4 had LA maximum volume similar to that of normal controls from decade 8 (27.8 ± 4.3 mL/m(2) vs 25.6 ± 6.1 mL/m(2) respectively, P = .22). Active emptying volume and fraction were higher in the HT group across all decades, while there was no difference between the HT and normal groups for passive emptying volume. LV mass and E/E' ratio were significantly higher across all decades in the HT group. HT alters atrial dynamics significantly, with resultant increased LA volume and active emptying volume consequent to altered LV diastolic function. HT 'accelerates' the normal aging process with patients as early as decade 4 having similar LA size to that of normal controls in decade 8. This premature increase in LA volume may result in the future development of atrial fibrillation in HT patients.

How should we measure left atrium size and function?

Echocardiographic assessment of left atrial size from M-mode or 2D echocardiography measurements has been used in clinical and research studies for years, but its accuracy is now questioned. New techniques, such as 3D and tissue Doppler imaging, assessing velocities, strain and strain rate, provide improved prognostic value in a wide range of diseases. 2D strain imaging using speckle tracking on B-mode images may yield even better, angle-independent, results than tissue Doppler imaging-derived strain echocardiography. Finally, velocity vector imaging is a novel image analysis technique that may be used to quantify left atrial volume.

Impact of reduced left atrial functions on diagnosis of paroxysmal atrial fibrillation: results from analysis of time-left atrial volume curve determined by two-dimensional speckle tracking

BACKGROUND

Atrial fibrillation is commonly associated with impaired reservoir and booster functions of the left atrium (LA). Recent advances in two-dimensional speckle tracking technique (2DST) enabled automatic analysis of the time-LA volume curve representing these functions. Our objective was to evaluate LA function in patients with or without paroxysmal atrial fibrillation (PAF) using 2DST.

METHODS

We studied 111 patients (68 men, age 62 ± 16 years) with (n = 53) or without (n = 58) PAF. After constructing time-LA volume curves from the apical four and two chamber views (iE33, Philips with QLAB 6.0, Philips Medical Systems, Bothell, WA, USA), maximal LA volume (LAVmax), preatrial contraction LA volume (LAVpreA), and minimum LA volume (LAVmin) were obtained. Then, LA reservoir volume (ARV=LAVmax-LAVmin) and active emptying volume (AEV=LAVpreA-LAVmin) were calculated to determine ARV/LAVmax as reservoir function and AEV/LAVpreA as booster pump function.

RESULTS

PAF was associated with greater LAVmax than that in controls (80 ± 21 ml versus 65 ± 16 ml, p < 0.001) and with reduced reservoir and booster functions (ARV/LAVmax 46 ± 9% versus 52 ± 7%; AEV/LAVpreA 29 ± 10% versus 36 ± 6%, p < 0.001). Multivariate logistic analysis demonstrated that ARV/LAVmax and AEV/LAVpreA were closely associated with the existence of PAF.

CONCLUSION

These results demonstrate that the present 2DST enables determining LA reservoir and booster functions, providing insights into the diagnosis of PAF.

Left atrial volume combined with atrial pump function identifies hypertensive patients with a history of paroxysmal atrial fibrillation

Identifying patients at high risk for the occurrence of atrial fibrillation is one means by which subsequent thromboembolic complications may be prevented. Left atrial enlargement is associated with progression of atrial remodeling, which is a substrate for atrial fibrillation, but impaired atrial pump function is also another aspect of the remodeling. Our objective was to differentiate patients with a history of paroxysmal atrial fibrillation using echocardiography. We studied 280 hypertensive patients (age: 66+/-7 years; left ventricular ejection fraction: 65+/-8%), including 140 consecutive patients with paroxysmal atrial fibrillation and 140 age- and sex-matched control subjects. Left atrial volume was measured using the modified Simpson method at both left ventricular end systole and preatrial contraction and was indexed to body surface area. Peak late-diastolic mitral annular velocity was measured during atrial contraction using pulsed tissue Doppler imaging as an atrial pump function. Left atrial volume index measured at left ventricular end systole had a 74% diagnostic accuracy and a 71% positive predictive value for identifying patients with paroxysmal atrial fibrillation; these values for the ratio of left atrial volume index at left ventricular end systole to the peak late-diastolic mitral annular velocity were 82% and 81%, respectively, and those for the ratio of left atrial volume index at preatrial contraction to the peak late-diastolic mitral annular velocity were 86% and 90%, respectively. In conclusion, left atrial size combined with atrial pump function enabled a more accurate diagnosis of a history of paroxysmal atrial fibrillation than conventional parameters.

Impact of Mild Hypertension on Left Atrial Size and Function

Background— Left atrial (LA) enlargement has been documented to occur in moderate and severe hypertension.

Methods and Results— One hundred twelve mild hypertension patients were prospectively recruited and compared with 198 healthy volunteers. All recruits had a transthoracic echocardiogram. Maximum LA biplane volume, minimum LA biplane volume, and pre ‘p’-LA biplane volume were measured, and left atrial passive, active emptying, and conduit volumes were calculated at baseline and in a subgroup of patients after 12 months. After adjusting for age, gender, and body mass index, maximum LA biplane volume, pre ‘p’-LA biplane volume, and their indexed volumes were increased in the hypertension group. Active emptying volume and fraction were significantly increased in the hypertension group, with no change in conduit and passive volumes. Subgroup analysis comparing hypertensives with normal/mildly increased left ventricular mass (group 1) with those with moderate/severely increased left ventricular mass (group 2) at baseline demonstrated that maximum LA biplane volume (62.8�17.9 mL versus 45.4�13.7 mL; P <0.001) was significantly increased in group 2. Active emptying volume was also increased.

Conclusion— Even mild hypertension seems to be associated with a reduction in early diastolic filling. This results in augmented late left ventricular diastolic filling due to active atrial contraction and may be the mechanism for the increase in left atrial size.

Effect of left atrial size and function on P-wave dispersion: a study in patients with paroxysmal atrial fibrillation

BACKGROUND

Paroxysmal atrial fibrillation (PAF), a common arrhythmia, is caused by the fractionated and nonhomogeneous propagation of sinus impulse.

HYPOTHESIS

This study was undertaken to examine the effect of left atrial (LA) dimension and function on P-wave dispersion (deltaP) in unselected patients with PAF and health controls.

METHOD

In this study, 62 consecutive patients with PAF (32 men, 30 women, mean age 55+/-11 years) and 62 age- and gender-matched healthy controls (33 men, 29 women, mean age 52+/-13 years) were studied to compare the effect of LA size, volume, and function on deltaP (difference between maximum and minimum P-wave duration on 12-lead electrocardiogram).

RESULTS

P-wave dispersion in patients with PAF and normal LA diastolic diameter (LAD) was longer than that in controls with normal LA size (53+/-8 vs. 34+/-8 ms, p < 0.001). P-wave dispersion increased in patients with PAF (62+/-12 vs. 53+/-8 ms, p = 0.003) and controls (40+/-7 vs. 34+/-8 ms, p = 0.005) with increased LAD. Presence or absence of PAF did not interact with LAD for their effect on deltaP (2 x 2 analysis of variance test p = 0.20). In the PAF group, deltaP correlated with LAD (r = 0.43, p = 0.002), LA diastolic volume (r = 0.6, p < 0.001), and LA ejection fraction (AEF) (r = - 0.33, p = 0.05). The AEF was preserved when LAD increased in the patients without PAF (0.52+/-0.07 vs. 0.57+/-0.10, p = NS), however was significantly decreased in the PAF group (0.37+/-0.12 vs. 0.49+/-0.10, p = 0.01). On multivariate logistic regression analysis, only deltaP retained significance on development of PAF.

CONCLUSION

It was concluded that deltaP increased in patients with PAF and normal LA size. In controls with increased LA size, deltaP increased but did not reach the levels attained in patients with PAF. The AEF was decreased in patients with PAF but was preserved in those without PAF. These findings can be explained by the changes in LA microarchitecture which concurrently decreased atrial myocardial contraction, increased deltaP, and predisposed to PAF.

WITHDRAWN: Left atrial function and arterial hypertension

Left atrial enlargement is frequently observed in many cardiac diseases. One of the main determinants of left atrial size is ventricular diastolic function. It has recently been suggested that left atrial volume might be the morphophysiologic expression of long-term modifications induced by diastolic function. Furthermore, left ventricular remodelling, such as it happens in hypertensive patients, is another important determinant of atrial volume. All the volumetric modifications of the left atrium, during cardiac cycle, are involved in hypertensive damage. Therefore, left atrial function impairment represents the result of morphological and haemodynamic alterations observed in hypertension. Actually, many techniques, invasive and non-invasive, are available with the purpose to investigate the real atrial dimensions and provide a suitable assessment of atrial function. Recently, it has been demonstrated that the degree of left atrial enlargement is associated with adverse prognosis in different clinical setting. The predictive value of left atrial volume seems to be independent of left ventricular systolic and diastolic function, but the use of left atrial volume for risk stratification is yet an evolving science: more data are required with respect to the natural history of left atrial remodelling in disease, the degree of left atrial modifiability with therapy and whether regression of left atrial size translates into improved cardiovascular outcome.Journal of Human Hypertension advance online publication, 14 August 2008; doi:10.1038/jhh.2008.96.

Assessment of atrial electromechanical coupling and influential factors in nonrheumatic paroxysmal atrial fibrillation

BACKGROUND

Sequential analysis of atrial electromechanical coupling (P-A) by Doppler tissue imaging (DTI) might provide important insight into the mechanisms of paroxysmal atrial fibrillation (PAF).

HYPOTHESIS

The purpose of this study was to evaluate P-A and the dispersion of P-A, and to analyze the influential factors of P-A.

METHODS

One hundred and ten patients with PAF and 87 normal controls were enrolled. Using DTI, the time intervals from the beginning of P-wave to the onset of atrioventricular ring motion related to atrial contraction were measured.

RESULTS

Atrial electromechanical coupling at the interventricular septum atrioventricular annulus (P-A1), left lateral mitral annulus (P-A2) and right lateral tricuspid annulus (P-A3) in PAF group were significantly longer than those in control (p < 0.001). The difference between P-A2 and P-A1 (T1), P-A2 and P-A3 (T3) in PAF group were greater than those in control before age correction (p < 0.05). The linear regression analysis showed that the duration of PAF episodes and age were the greatest influential factors of P-A1 (r = 0.564). Left atrial anterior-posterior dimension (LAD) and age were the greatest influential factors of P-A2 (r = 0.459). The LAD was the greatest influential factors of T1 and T3 (r = 0.408, 0.542).

CONCLUSIONS

The atrial electromechanical coupling was significantly longer and the dispersion of P-A at left lateral mitral annulus was greater in PAF patients. The prolongation of P-A may be related to left atrial enlargement, long episodes of PAF and aging and the dispersion of P-A at left lateral mitral annulus to LAD.

Metabolic syndrome and risk of development of atrial fibrillation: the Niigata preventive medicine study

BACKGROUND

The metabolic syndrome consists of a cluster of atherosclerotic risk factors, many of which also have been implicated in the genesis of atrial fibrillation (AF). However, the precise role of the metabolic syndrome in the development of AF is unknown.

METHODS AND RESULTS

This prospective, community-based, observational cohort study was based on an annual health check-up program in Japan. We studied 28 449 participants without baseline AF. We used 2 different criteria for the metabolic syndrome--the guidelines of the National Cholesterol Education Program Third Adult Treatment Panel (NCEP-ATP III) and those of the American Heart Association/National Heart, Lung, and Blood Institute (AHA/NHLBI)--to study the risk of development of new-onset AF. The metabolic syndrome was present in 3716 subjects (13%) and 4544 subjects (16%) using the NCEP-ATP III and AHA/NHLBI definitions, respectively. During a mean follow-up of 4.5 years, AF developed in 265 subjects (105 women). Among the metabolic syndrome components, obesity (age- and sex-adjusted hazard ratio [HR], 1.64), elevated blood pressure (HR, 1.69), low high-density lipoprotein cholesterol (HR, 1.52), and impaired fasting glucose [corrected] (HR, 1.44 [NCEP-ATP III] and 1.35 [AHA/NHLBI]) showed an increased risk for AF. The association between the metabolic syndrome and AF remained significant in subjects without treated hypertension or diabetes by the NCEP-ATP III definition (HR, 1.78) but not by the AHA/NHLBI definition (HR, 1.28).

CONCLUSIONS

The metabolic syndrome was associated with increased risk of AF. The metabolic derangements of the syndrome may be important in the pathogenesis of AF.

Augmentation of Pulmonary Vein Backflow Velocity during Left Atrial Contraction: A Novel Phenomenon Responsible for Progression of Atrial Fibrillation in Hypertensive Patients

BACKGROUND

Atrial fibrillation (AF) is a common arrhythmia showing disease progression. However, echocardiographic prediction of such progression remains incomplete. This study aimed to identify echocardiographic predictors of AF progression in hypertensive patients.

METHODS

Hypertensive patients with paroxysmal AF were divided into two groups: patients with AF which became permanent (group A; n = 13) and those with AF which remained paroxysmal (group B; n = 46) during the same follow-up period (8.0 +/- 2.4 years). Clinical baselines showed no significant differences except for age. Transthoracic echocardiography was recorded 1-2 weeks after termination of the first-detected paroxysms of AF.

RESULTS

Echocardiography showed greater left atrial (LA) dimension (p = 0.023) and late diastolic pulmonary vein (PV) backflow velocity (p < 0.001), and a lower LA fractional shortening (p = 0.008) in group A than in group B. Multilogistic regression analysis demonstrated that augmented PV backflow (p = 0.007) and reduced LA fractional shortening (p = 0.032) were independent predictors of the progression of AF. The receiver-operating characteristic curve demonstrated that PV backflow augmentation is the best predictor of future AF perpetuation.

CONCLUSION

PV backflow leading to cyclic stretching of PV musculature contributes to AF progression.

Echocardiographic features of patients with paroxysmal atrial fibrillation

BACKGROUND

There are several risk factors for the initiation of paroxysmal atrial fibrillation (PAF) and the underlying mechanisms are multifactorial. Our study aims to explore the echocardiographic parameters that can identify in patients with PAF compared to normal subjects.

METHODS

Eighty consecutive patients who were with PAF detected by 24-h Holter monitoring (HM) were assigned in our study. The control group (n = 80) consisted individuals with no PAF on HM. Indication for HM was palpitations at rest. All patients underwent routine echocardiographic evaluation. Patients with aortic and mitral stenosis, hyperthyroidism, and hypothyroidism were excluded from the study. Comprehensive clinical data were collected.

RESULTS

Mean age of the patients with PAF was 63 +/- 11 years and of those 42% were male subjects. There was no difference in the prevalence of hypertension in both groups. Mean left ventricular ejection fraction (LVEF) was 57 +/- 15% in PAF group and 64 +/- 2% in control subjects (p < 0.001). Mean values of left atrial (LA) diameter for PAF and control groups were 3.7 +/- 0.6 cm vs. 3.1 +/- 0.4 cm (p < 0.001), respectively. Patients with PAF had more severe valve insufficiency, higher values of mean pulmonary artery systolic pressures (PAP) (29 +/- 10 mmHg vs. 25 +/- 2 mmHg, respectively; p = 0.001) and deteriorated MV inflow velocities (E:A ratio 0.9 +/- 0.4 vs. 1.1 +/- 0.3, respectively; p = 0.008) when compared to control group. In multivariate logistic regression analysis, LA diameter predicted the development of PAF after adjusted for age and gender.

CONCLUSION

Our results indicate that LA diameter predicts the development of PAF.

Noninvasive assessment of left atrial function by strain rate imaging in patients with hypertension: a possible beneficial effect of renin-angiotensin system inhibition on left atrial function

Renin-angiotensin system (RAS) inhibitors are likely to reduce the development of atrial fibrillation by preventing atrial fibrosis. Strain rate (SR) imaging is a novel echocardiographic technique to quantify left atrial (LA) function. However, it has not been determined whether SR imaging is applicable for detection of LA dysfunction in hypertensive (HT) patients. We used SR imaging to assess alteration in LA function in HT patients and its modification by RAS inhibitors. SR imaging was performed in 80 HT patients and 50 age-matched normotensive (NT) subjects. HT patients were divided into two groups according to left ventricular hypertrophy (LVH) and LA dilatation. Peak SR was measured at each LA segment (septal, lateral, posterior, anterior, and inferior) and mean peak systolic SR (SR-LAs) was calculated by averaging data in each segment. Mean SR-LAs levels in the dilated LA group (1.97+/-0.45 s(-1), n=25) and non-dilated LA group (2.15+/-0.57 s(-1), n=55) were significantly (p<0.05) lower than that in NT subjects (2.53+/-0.71 s(-1)). Irrespective of the presence or absence of LVH, mean SR-LAs in HT patients was lower than that in NT subjects. When RAS inhibitors were used, the mean SR-LAs level in the non-dilated LA group was equivalent to that in NT subjects. In HT patients, mean SR-LAs, an index of LA reservoir function, decreases before development of LA enlargement and LVH. Treatment with RAS inhibitors appears to preserve LA reservoir function in HT patients without dilated LA. SR imaging can detect LA dysfunction in HT patients and is useful for evaluation of the therapeutic benefit on LA reservoir function.

Losartan prevents stretch-induced electrical remodeling in cultured atrial neonatal myocytes

Atrial fibrillation (AF) is the most frequent arrhythmia found in clinical practice. In recent studies, a decrease in the development or recurrence of AF was found in hypertensive patients treated with angiotensin-converting enzyme inhibitors or angiotensin receptor-blocking agents. Hypertension is related to an increased wall tension in the atria, resulting in increased stretch of the individual myocyte, which is one of the major stimuli for the remodeling process. In the present study, we used a model of cultured atrial neonatal rat cardiomyocytes under conditions of stretch to provide insight into the mechanisms of the preventive effect of the angiotensin receptor-blocking agent losartan against AF on a molecular level. Stretch significantly increased protein-to-DNA ratio and atrial natriuretic factor mRNA expression, indicating hypertrophy. Expression of genes encoding for the inward rectifier K(+) current (I(K1)), Kir 2.1, and Kir 2.3, as well as the gene encoding for the ultrarapid delayed rectifier K(+) current (I(Kur)), Kv 1.5, was significantly increased. In contrast, mRNA expression of Kv 4.2 was significantly reduced in stretched myocytes. Alterations of gene expression correlated with the corresponding current densities: I(K1) and I(Kur) densities were significantly increased in stretched myocytes, whereas transient outward K(+) current (I(to)) density was reduced. These alterations resulted in a significant abbreviation of the action potential duration. Losartan (1 microM) prevented stretch-induced increases in the protein-to-DNA ratio and atrial natriuretic peptide mRNA expression in stretched myocytes. Concomitantly, losartan attenuated stretch-induced alterations in I(K1), I(Kur), and I(to) density and gene expression. This prevented the stretch-induced abbreviation of action potential duration. Prevention of stretch-induced electrical remodeling might contribute to the clinical effects of losartan against AF.

Strain rate imaging for noninvasive functional quantification of the left atrium: comparative studies in controls and patients with atrial fibrillation

Strain rate (SR) imaging enables quantitative measurement of left ventricular (LV) function independent of cardiac translation. However, whether SR imaging is applicable for detection of left atrial (LA) dysfunction remains unknown. The purpose of this study was to assess the feasibility of measuring LA function by SR imaging, focusing on the effects of aging and LA dilatation during atrial fibrillation (AF). Echocardiographic evaluation including SR imaging was performed in 50 controls (29 males and 21 females; mean age, 41 +/- 14 years) and in 27 patients with AF (15 males and 12 females; mean age, 62 +/- 12 years; 8 with persistent AF and 19 with paroxysmal AF) from 3 apical views and analyzed off-line. Peak SR was measured at each LA segment (septum, lateral, posterior, anterior, and inferior), and mean peak systolic SR (SR-LAs), early diastolic SR (SR-LAe), and late diastolic SR (SR-LAa) were calculated by averaging the results for each segment. LA dimension, peak mitral and pulmonary velocities at late diastole, LA fractional shortening, and atrial filling fraction were calculated as parameters of LA function. Normal values for mean SR-LAs, SR-LAe, and SR-LAa were 3.4 +/- 1.0 s -1 , -3.9 +/- 1.7 s -1 , and -3.1 +/- 1.0 s -1 , respectively, and they were successfully measured in more than 95% of the LA segments. In controls, both mean SR-LAs and mean SR-LAe correlated with age, LA dimension, and early to late diastolic mitral flow velocity ratio. Conversely, mean SR-LAa did not show significant correlation with age or parameters of LA function. In AF patients, mean SR-LAs was correlated inversely with age. The mean SR-LAs was significantly lower in persistent AF patients than in age-matched controls (1.7 +/- 0.8 vs 2.9 +/- 0.9 s -1 ; P < .01). Based on our findings, we conclude that noninvasive quantification of LA function using SR imaging enables evaluation of LA dysfunction due to aging and LA dilatation.

Atrial myocardial deformation properties predict maintenance of sinus rhythm after external cardioversion of recent-onset lone atrial fibrillation: a color Doppler myocardial imaging and transthoracic and transesophageal echocardiographic study

BACKGROUND

Accurate echocardiographic parameters to predict maintenance of sinus rhythm in patients with atrial fibrillation (AF) are poorly defined. This study was conducted to assess the atrial myocardial properties during AF through myocardial velocity, strain rate, and strain and to compare their prognostic value in maintaining sinus rhythm in patients with lone AF with standard transthoracic (TTE) and transesophageal echocardiography (TEE).

METHODS AND RESULTS

Sixty-five consecutive patients with lone AF for < or =3 months underwent TTE, TEE, and myocardial velocity and strain and strain rate imaging examinations before successful external cardioversion. Maintenance of sinus rhythm was assessed during a 9-month follow-up. Atrial myocardial velocity, strain, and strain rate values in AF patients were compared with those of age- and sex-matched referents. Moreover, clinical and echocardiographic parameters of patients with maintenance of sinus rhythm (MSR patients) over the 9-month follow-up period (n=25) were compared with those from patients with AF recurrence (AFR patients; n=40). Atrial myocardial properties assessed by myocardial velocity, strain rate, and strain were significantly reduced (P<0.0001) in patients (velocity, 3.2+/-1.4 cm/s; strain, 23.3+/-19%; strain rate, 2+/-0.9 seconds(-1)) compared with referents (velocity, 5.7+/-1.3 cm/s; strain, 92+/-26%; strain rate, 4.2+/-1.8 seconds(-1)). The individual predictors of sinus rhythm maintenance were atrial appendage flow velocity (MSR patients, 39+/-12 cm/s; AFR patients, 32+/-15 cm/s; P<0.01) assessed by TEE and atrial strain (MSR patients, 33+/-27%; AFR patients, 17+/-9%; P=0.0007) and strain rate (MSR patients, 2.7+/-1 seconds(-1); AFR patients, 1.6+/-0.6 seconds(-1); P<0.0001) peak systolic values. Atrial strain (P<0.0001; coefficient, 0.015; SE, 0.003) and strain rate (P<0.0001; coefficient, 0.372; SE, 0.075) parameters alone were confirmed as independent predictors of sinus rhythm maintenance by multivariable analysis.

CONCLUSIONS

Patients with higher atrial strain and strain rate appear to have a greater likelihood of staying in sinus rhythm. If the current data are verified in future studies, then additional pharmacological therapy and maintenance of anticoagulants for a longer period may need to be considered in those with lower atrial strain and strain rate measurements.

Doppler tissue analysis of atrial electromechanical coupling in paroxysmal atrial fibrillation

The aim of this study was to: (1) evaluate atrial electromechanical coupling using M-mode Doppler tissue; and (2) test its clinical impact for detecting atrial abnormalities in paroxysmal atrial fibrillation (AF). Using Doppler tissue, the time intervals from the onset of P wave until the backward motions of the right and left atrioventricular rings in the apical 4-chamber view corresponding to the atrial contractions were measured. In paroxysmal AF group, these intervals were significantly longer than in the control group. Using the criteria that an abnormal time interval from the onset of P wave until the backward motion of the left atrioventricular ring is longer than 112 milliseconds, the sensitivity, the specificity, and the positive predictive values for paroxysmal AF are 73%, 93%, and 93%, respectively. This parameter is affected in patients with paroxysmal AF and should be useful for detecting atrial impairment related to paroxysmal AF.

Does impaired left ventricular relaxation affect P wave dispersion in patients with hypertension?

OBJECTIVE

P wave dispersion (PD) is considered to reflect the heterogeneous conduction in atria. We investigated whether there was a correlation between the left ventricular (LV) relaxation and PD.

METHOD AND RESULTS

Fifty-three hypertensive patients < or =60 years old were divided into two groups: Group A, 27 patients, aged 54+/-5 years with the impaired LV relaxation and Group B, 26 patients, aged 51+/-8 years with normal LV relaxation. The P wave durations were measured in all 12 leads of ECG and PD was defined as the difference between maximum and minimum P wave duration (Pmax-Pmin). Mitral inflow velocities (E and A), E deceleration time (DT), isovolumic relaxation time (IVRT), left atrial and ventricular diameters, and wall thickness of LV were obtained by echocardiography. Clinical characteristics of both groups were comparable. The wall thickness of LV, Pmax, and left atrial dimension were not different in both groups. A velocity was higher (P<0.001), but E velocity (P=0.03) and E/A ratio (P<0.001) were lower in group A than in group B. IVRT and DT were also significantly longer in group A. PD was significantly higher in group A compared to group B (51+/-9 vs 41+/-11 ms, P=0.01). This difference resulted from the Pmin (61+/-10 vs 67+/-9 ms, P=0.03, respectively). Multivariate analysis revealed a significant correlation between PD and A velocity (r=0.46, P=0.01), E/A ratio (r=-0.53, P=0.001), DT (r=0.65, P<0.001), and IVRT (r=0.73, P<0.001).

CONCLUSION

This study suggests that impaired LV relaxation contributes to the heterogeneous atrial conduction in hypertensive patients.

The effect of exercise to P wave dispersion and its evaluation as a predictor of atrial fibrillation

AIM

Prolongation of P wave time and increase of its dispersion as an independent predictor of atrial fibrillation. In patients with paroxysmal atrial fibrillation (PAF) as in healthy people, exercise augments sympathetic activity and therefore can cause the development of atrial fibrillation. The aim of this study is to evaluate the effect of exercise on P wave dispersion and to predict the development of atrial fibrillation.

METHODS

One hundred and ninety-eight patients (93 women, 105 men, mean age: 59.05 +/- 11.01 years) having the diagnosis of PAF were included in the study. The left atrial diameter of all these patients was more than 4.0 cm. One hundred and fifty-five patients (72 females, 83 males, mean age: 58.41 +/- 10.79 years), with left atrial diameter more than 4.0 cm and without PAF were taken as control group. Symptom limited exercise test with modified Bruce protocol was performed on all patients. Rest, maximum exercise and recovery, and first, third, and fifth-minute 12-derivation ECG was taken in all patients. The velocity of ECG was adjusted to 50 mm/s; shortest and largest P wave durations were measured and P wave dispersion was calculated.

RESULTS

The mean left atrial diameter was 4.41 +/- 0.58 cm in PAF patients and 4.38 +/- 0.48 cm in control group. No differences were found between PAF patients with the controls in exercise time (10.38 +/- 2.93 vs 10.81 +/- 2.75 minutes); METs (6.98 +/- 1.72 vs 7.28 +/- 1.75 minutes); resting heart rate (79.13 +/- 14.86 vs 79.69 +/- 10.43 bpm); peak heart rate (146.83 +/- 23.21 vs 146.94 +/- 16.13 bpm). Maximum exercise P wave duration and P wave dispersion were greater than the rest measurements in PAF group (respectively P < 0.0001 and P = 0.0004).

CONCLUSION

In PAF patients, P wave dispersion is significantly longer at rest, maximum exercise and recovery time than in a control group without PAF.

Atrial fibrillation: hypertension as a causative agent, risk factor for complications, and potential therapeutic target

Atrial fibrillation and hypertension are 2 prevalent, and often coexistent, conditions in the North American population. Their incidence increases with advancing age, and they are responsible for considerable morbidity and mortality. Although the relation between the 2 conditions has long been known, the treatment of hypertension is not currently a focus in the clinical management of atrial fibrillation. Hypertension is associated with left ventricular hypertrophy, impaired ventricular filling, left atrial enlargement, and slowing of atrial conduction velocity. These changes in cardiac structure and physiology favor the development of atrial fibrillation, and they increase the risk of thromboembolic complications. Conventional therapy of atrial fibrillation has focused on interventions to control heart rate and rhythm and the prevention of stroke through the use of anticoagulant medications. In patients with atrial fibrillation, aggressive treatment of hypertension may reverse the structural changes in the heart, reduce thromboembolic complications, and retard or prevent the occurrence of atrial fibrillation. Specific pharmacotherapy could potentially play a major role in the primary and secondary prevention of atrial fibrillation and its complications.

Doppler transmitral flow indexes and risk of atrial fibrillation (the Framingham Heart Study)

Atrial fibrillation (AF) is characterized by structural remodeling and atrial systolic failure. It is unclear if atrial filling abnormalities precede the onset of AF. We evaluated 942 Framingham Study subjects (587 women; mean age 75 years) who underwent Doppler echocardiographic evaluation at a routine examination and who did not have a history of AF. We used multivariable Cox regression models (stratified by gender and prevalent cardiovascular disease) to examine the relations of Doppler transmitral flow indexes (ratio of the velocity-time integrals of the early [E] and late [A] diastolic filling waves [VTI E/A], a correlate of atrial conduit function; E-wave deceleration time; the atrial filling fraction, an index of atrial systolic function; and peak A wave velocity) to the incidence of AF. At follow-up (mean 7 years), 85 subjects (41 women) developed AF. In models adjusting for established risk factors for AF (including left atrial size) at baseline, and for heart failure and myocardial infarction on follow-up, a 1 SD increment in VTI E/A was associated with a 28% increase in risk of AF (hazards ratio 1.28, 95% confidence interval 1.02 to 1.59). A 1 SD decrease in the atrial filling fraction was associated with a 28% higher risk of AF (hazards ratio 1.28, 95% confidence interval 0.98 to 1.67). There was a U-shaped relation between peak A-wave velocity and risk of AF. Thus, in our elderly community-based sample, increased VTI E/A and a low atrial filling fraction were markers of increased risk of AF, suggesting that altered atrial filling may antedate AF.