Left atrial volume and function assessment by magnetic resonance imaging

Obstructive Sleep Apnea as a Predictor of Inducible Atrial Flutter During Pulmonary Vein Isolation in Patients With Atrial Fibrillation: Clinical Significance and Follow-Up Outcomes

Background

Atrial fibrillation (AF) and atrial flutter (AFL) often coexist in patients and may lead to severe symptoms and complications. Despite their coexistence, prophylactic cavotricuspid isthmus (CTI) ablation has failed to reduce the incidence of recurrent AF or new onset AFL. In contrast, the presence of inducible AFL during pulmonary vein isolation (PVI) has been shown to be predictive of symptomatic AFL during follow-up. However, the potential role of obstructive sleep apnea (OSA) as a predictor of inducible AFL during PVI in patients with AF remains unclear. Therefore, this study aimed to examine the potential role of OSA as a predictor of inducible AFL during PVI in patients with AF and reexamine the clinical significance of inducible AFL during PVI in terms of recurrent AFL or AF during follow-up.

Methods

We conducted a single-center, non-randomized retrospective study on patients who underwent PVI between October 2013 and December 2020. A total of 192 patients were included in the study after screening 257 patients for exclusion criteria, which included a previous history of AFL or previous PVI or Maze procedure. All patients underwent a transesophageal echocardiogram (TEE) prior to their ablation to rule out a left atrial appendage thrombus. The PVI was performed using both fluoroscopic and electroanatomic mapping derived from intracardiac echocardiography. After the confirmation of PVI, additional electrophysiology (EP) testing was performed. AFL was classified as typical or atypical based on the origin and activation pattern. Descriptive and frequency statistics were performed to describe the demographic and clinical characteristics of the sample, and Chi-square and Fisher's exact tests were used to compare independent groups on categorical outcomes. Logistic regression analysis was performed to adjust for confounding variables. The study was approved by the Institutional Review Board, and informed consent was waived given the retrospective nature of the study.

Results

Of the 192 patients included in the study, 52% (n = 100) had inducible AFL after PVI, with 43% (n = 82) having typical right AFL. Bivariate analysis showed statistically significant differences between the groups for OSA (P = 0.04) and persistent AF (P = 0.047) when examining the outcome of any inducible AFL. Similarly, only OSA (P = 0.04) and persistent AF (P = 0.043) were significant when examining the outcome of typical right AFL. Multivariate analysis showed that only OSA was significantly associated with any inducible AFL after controlling for other variables (adjusted odds ratio (AOR) = 1.92, 95% confidence interval (CI): 1.003 - 3.69, P = 0.049). Of the 100 patients with inducible AFL, 89 underwent additional ablation for AFL prior to completion of their procedure. At 1 year, the rates of recurrence for AF, AFL, and either AF or AFL were 31%, 10%, and 38%, respectively. There was no significant difference in the rates of recurrence of AF, AFL, or either AF/AFL at 1 year when accounting for the presence of inducible AFL or the efficacy of additional AFL ablation.

Conclusions

In conclusion, our study found a high incidence of inducible AFL during PVI, particularly among patients with OSA. However, the clinical significance of inducible AFL in relation to the recurrence rates of AF or AFL at 1-year post-PVI remains unclear. Our findings suggest that successful ablation of inducible AFL during PVI may not provide clinical benefit in reducing AF or AFL recurrence. To establish the clinical significance of inducible AFL during PVI in various patient populations, further prospective studies with larger sample sizes and longer follow-up periods are necessary.

Quantification of Myocardial Deformation in Patients with Takayasu Arteritis by Cardiovascular Magnetic Resonance Feature Tracking Imaging

BACKGROUND

Cardiac involvement is one of the main causes of morbidity and mortality in patients with Takayasu arteritis (TA). Early detection and intervention of cardiac damage may be helpful to reduce the mortality of TA. Magnetic resonance (MR) imaging (MRI)-derived feature tracking (FT) is an effective quantitative method to assess myocardial deformation which may reflect early changes of cardiac function.

PURPOSE

To explore the utility of MR-FT as a method to detect cardiac damage in TA patients.

STUDY TYPE

Retrospective.

POPULATION

Fifty-seven TA patients who had undergone clinically indicated MRI and 57 healthy controls.

FIELD STRENGTH/SEQUENCES

Balanced steady-state free precession rest cine and 2D phase-sensitive inversion recovery breath-hold segmented gradient echo late gadolinium enhancement (LGE) sequences at 3.0 T.

ASSESSMENT

Based on LGE images, TA patients were divided into two subgroups, LGE (+) subgroup (N = 12) and LGE (-) subgroup (N = 45). In addition, patients were further subdivided into impaired (N = 26) and preserved left ventricle ejection fraction (LVEF) subgroups (N = 31). FT-derived deformation indices, including left ventricular (LV) global longitudinal strain (GLS), were measured by commercial software.

STATISTICAL TESTS

Mann-Whitney U-test, Kruskal-Wallis test followed by Dunn-Bonferroni post hoc method, and receiver operating characteristic curve analysis were conducted. A P-value of <0.05 was considered statistically significant.

RESULTS

GLS was significantly worse in TA than in controls (median [interquartile range, IQR]: TA -10.0 [-7.5 to 12.4] vs. controls -12.7 [-11.8 to 14.7]). Moreover, TA patients with LGE (+) had significantly poorer GLS than those with LGE (-) (median [IQR]: LGE (+) -6.8 [-4.0 to 8.1] vs. LGE (-) -10.7 [-8.5 to 12.9]). The reduced LVEF subgroup had significantly greater cardiac dysfunction as measured by MR-FT than the preserved LVEF subgroup (GLS median [IQR]: reduced LVEF -7.9 [-6.2 to 11.4] vs. preserved LVEF -10.8 [-8.6 to 13.5]).

DATA CONCLUSION

Myocardial deformation impairment was found in the majority of TA patients. MR-FT imaging may be helpful in the early diagnosis and management of TA patients.

LEVEL OF EVIDENCE

4 TECHNICAL EFFICACY STAGE: 5.

Saturation recovery-prepared magnetic resonance angiography for assessment of left atrial and esophageal anatomy

OBJECTIVES

Magnetic resonance angiography (MRA) has been established as an important imaging method in cardiac ablation procedures. In pulmonary vein (PV) isolation procedures, MRA has the potential to minimize the risk of severe complications, such as atrio-esophageal fistula, by providing detailed information on esophageal position relatively to cardiac structures. However, traditional non-gated, first-pass (FP) MRA approaches have several limitations, such as long breath-holds, non-uniform signal intensity throughout the left atrium (LA), and poor esophageal visualization. The aim of this observational study was to validate a respiratory-navigated, ECG-gated (EC), saturation recovery-prepared MRA technique for simultaneous imaging of LA, LA appendage, PVs, esophagus, and adjacent anatomical structures.

METHODS

Before PVI, 106 consecutive patients with a history of AF underwent either conventional FP-MRA (n = 53 patients) or our new EC-MRA (n = 53 patients). Five quality scores (QS) of LA and esophagus visibility were assessed by two experienced readers. The non-parametric Mann-Whitney U-test was used to compare QS between FP-MRA and EC-MRA groups, and linear regression was applied to assess clinical contributors to image quality.

RESULTS

EC-MRA demonstrated significantly better image quality than FP-MRA in every quality category. Esophageal visibility using the new MRA technique was markedly better than with the conventional FP-MRA technique (median 3.5 [IQR 1] vs median 1.0, p < 0.001). In contrast to FP-MRA, overall image quality of EC-MRA was not influenced by heart rate.

CONCLUSION

Our ECG-gated, respiratory-navigated, saturation recovery-prepared MRA technique provides significantly better image quality and esophageal visibility than the established non-gated, breath-holding FP-MRA. Image quality of EC-MRA technique has the additional advantage of being unaffected by heart rate.

ADVANCES IN KNOWLEDGE

Detailed information of cardiac anatomy has the potential to minimize the risk of severe complications and improve success rates in invasive electrophysiological studies. Our novel ECG-gated, respiratory-navigated, saturation recovery-prepared MRA technique provides significantly better image quality of LA and esophageal structures than the traditional first-pass algorithm. This new MRA technique is robust to arrhythmia (tachycardic, irregular heart rates) frequently observed in AF patients.

Association of left atrial structure and function and incident cardiovascular disease in patients with diabetes mellitus: results from multi-ethnic study of atherosclerosis (MESA)

AIMS

Diabetes mellitus (DM) is associated with the development of cardiovascular disease (CVD). Morphological changes in the left atrium (LA) may appear before symptoms. We aimed to investigate the association between cardiac magnetic resonance imaging (CMR) measured LA structure and function and incident CVD in asymptomatic individuals with DM.

METHODS AND RESULTS

Tissue tracking CMR was used to measure LA size and phasic function (emptying fractions and strain) on all 536 Multi-Ethnic Study of Atherosclerosis (MESA) participants with DM and available CMR at baseline in 2000-2002. At the time of enrolment, all participants were free of clinically recognized CVD, which was defined as MI, resuscitated cardiac arrest, angina, stroke, heart failure, and atrial fibrillation. Cox regression was used to assess the association of LA parameters with incident CVD adjusted for traditional cardiovascular risk factors, LV mass, NT Pro-BNP and maximum LA volume. Kaplan-Meier curves, adjusted for traditional risk factors, were generated for each LA measurement for the 25% of participants with the most abnormal values versus the remaining 75%. After a mean follow up of 11.4 ± 3.4 years, 141 individuals developed CVD. Individuals with incident CVD (mean age 66 years, 66% male vs. mean age 64 years, 50% male) had larger maximum and minimum LA volume index (LAVI) (32.1 vs. 26.8 mm3/m2; 19.4 vs. 14.2 mm3/m2 respectively, P < 0.001 for both), and lower total, passive, and active EF than those without CVD (P < 0.01 for all). In the fully adjusted model, there was a significant association of minimum LAVI, LA total EF, LA passive EF and LA active EF with incident CVD (HR 1.12 per mm3/m2, P < 0.001; HR 0.95 per %, P < 0.001; HR 0.97 per %, P = 0.021; HR 0.98 per %, P < 0.027, respectively).

CONCLUSIONS

CMR measured LA minimum volume and LA function as measured by emptying fraction are predictive of CVD in a diabetic multi-ethnic population free of any clinically recognized CVD at baseline.

Quantification of left atrial volume and phasic function using cardiovascular magnetic resonance imaging-comparison of biplane area-length method and Simpson's method

Left atrial (LA) enlargement and dysfunction are markers of chronic diastolic dysfunction and an important predictor of adverse cardiovascular and cerebrovascular outcomes. Accordingly, accurate quantification of left atrial volume (LAV) and function is needed. In routine clinical cardiovascular magnetic resonance (CMR) imaging the biplane area-length method (Bi-ALM) is frequently applied due to time-saving image acquisition and analysis. However, given the varying anatomy of the LA we hypothesized that the diagnostic accuracy of the Bi-ALM is not sufficient and that results would be different from a precise volumetric assessment of transversal multi-slice cine images using Simpson's method. Thirty one patients of the FIND-AF_RANDOMISED-study with status post acute cerebral ischemia (mean age 70.5 ± 6.2 years) received CMR imaging at 3T. The study protocol included cine SSFP sequences in standard 2- and 4 CV and a stack of contiguous slices in transversal orientation. Total, passive and active LA emptying fractions were calculated from LA maximal volume, minimal volume and volume prior to atrial contraction. Intra- and inter-observer variability was assessed in ten patients. Significant differences were found for LA volume and phasic function. The Bi-ALM significantly underestimated LA volume and overestimated LA function in comparison to Simpson's method (Bi-ALM vs. Simpson's method: LAV_max: 80.18 vs. 98.80 ml; LAV_pre-ac: 61.09 vs. 80.41 ml; LAV_min: 36.85 vs. 52.66 ml; LAEF_Total: 55.17 vs. 47.85%; LAEF_Passive: 23.96 vs. 19.15%; LAEF_Booster: 40.87 vs. 35.64%). LA volumetric and functional parameters were reproducible on an intra- and inter-observer levels for both methods. Intra-observer agreement for LA function was better for Simpson's method (Bi-ALM vs. Simpson's method; ICC LAEF_Total: 0.84 vs. 0.96; ICC LAEF_Passive: 0.74 vs. 0.92; ICC LAEF_Booster: 0.86 vs. 0.89). The Bi-ALM is based on geometric assumptions that do not reflect the complex individual LA geometry. The assessment of transversal slices covering the left atrium with Simpson's method is feasible and might be more suitable for an accurate quantification of LA volume and phasic function.

Right Atrial Volume is Increased in Corrected Tetralogy of Fallot and Correlates with the Incidence of Supraventricular Arrhythmia: A CMR Study

The aim of this study was to evaluate right atrial (RA) volume in corrected Tetralogy of Fallot (cTOF) and assess its correlation with the occurrence of supraventricular (SV) arrhythmia. Cardiac magnetic resonance imaging (CMR) and 24-h Holter were performed in n = 67 consecutive cTOF patients (age 30 ± 11.3 years). The CMR protocol included standard HASTE, SSFP cine, and blood flow measurements. Correlations between arrhythmia in ECG, heart volume, and functional parameters were investigated by negative binominal regression. Patients' characteristics (mean ± SD) included mean RA volume of 49 ± 19 ml/m(2) (HASTE sequence), mean right ventricular (RV) end-diastolic volume of 98 ± 27 ml/m(2), mean pulmonary valve regurgitation fraction (PR) of 21 ± 19 %, BMI of 25 kg/m(2), and heart rate of 75/min. Twenty-eight out of 67 patients experienced SV arrhythmia including SV couplets or bigeminus or longer non-sustained SV tachycardia (SVT) episodes. RA volume index was identified as an independent risk factor for different degrees of SV arrhythmia (SV couplets/bigeminus p < 0.001, SVT p < 0.001). Further risk factors for SV arrhythmia were male gender (p = 0.023) and decreased left ventricular (LV) ejection fraction (EF) (LV EF p < 0.001). RA volume is increased in adult patients with cTOF with larger RA volumes relating to higher incidence of SV arrhythmia. SV arrhythmia also appeared more often in male patients and those with decreased LV EF. Risk stratification according to these parameters could help to optimize early prevention and adjusted individual therapy to improve patient outcome and quality of life.

Quantitative tissue-tracking cardiac magnetic resonance (CMR) of left atrial deformation and the risk of stroke in patients with atrial fibrillation

BACKGROUND

Recent evidence suggests that left atrial (LA) dysfunction may be mechanistically contributing to cerebrovascular events in patients with atrial fibrillation (AF). We investigated the association between regional LA function and a prior history of stroke during sinus rhythm in patients referred for catheter ablation of AF.

METHODS AND RESULTS

A total of 169 patients (59 ± 10 years, 74% male, 29% persistent AF) with a history of AF in sinus rhythm at the time of pre-ablation cardiac magnetic resonance (CMR) were analyzed. The LA volume, emptying fraction, strain (S), and strain rate (SR) were assessed by tissue-tracking cardiac magnetic resonance. The patients with a history of stroke or transient ischemic attack (n=18) had greater LA volumes (Vmax and Vmin; P=0.02 and P<0.001, respectively), lower LA total emptying fraction (P<0.001), lower LA maximum and pre-atrial contraction strains (Smax and SpreA; P<0.001 and P=0.01, respectively), and lower absolute values of LA SR during left ventricular (LV) systole and early diastole (SRs and SRe; P=0.005 and 0.03, respectively) than those without stroke/transient ischemic attack (n=151). Multivariable analysis demonstrated that the LA reservoir function, including total emptying fraction, Smax, and SRs, was associated with stroke/transient ischemic attack (odds ratio 0.94, 0.91, and 0.17; P=0.03, 0.02, and 0.04, respectively) after adjusting for the CHA2DS2-VASc score and LA Vmin.

CONCLUSIONS

Depressed LA reservoir function assessed by tissue-tracking cardiac magnetic resonance is significantly associated with a prior history of stroke/transient ischemic attack in patients with AF. Our findings suggest that assessment of LA reservoir function can improve the risk stratification of cerebrovascular events in AF patients.

Left atrial volume assessment in atrial fibrillation using multimodality imaging: a comparison of echocardiography, invasive three-dimensional CARTO and cardiac magnetic resonance imaging

Left atrial size in atrial fibrillation is a strong predictor of successful ablation and cardiovascular events. Cardiac magnetic resonance multislice method (CMR-MSM) is the current gold standard for left atrial volume (LAV) assessment but is time consuming. We investigated whether LAV with more rapid area-length method by echocardiography (Echo-AL) or cardiac magnetic resonance (CMR-AL) and invasive measurement by 3D-CARTO mapping during ablation correlate with the CMR-MSM. We studied 250 consecutive patients prior to atrial fibrillation ablation. CMR images were acquired on 3T scanner to measure LAV by MSM and biplane area-length method. Standard echocardiography views were used to calculate LAV by biplane area-length method. LAV during ablation was measured by 3D-CARTO mapping. LAV was compared using intra-class correlation (ICC), Pearson's correlation and Bland-Altman plots. CMR-MSM was used as the reference standard. Mean LAV using CMR-MSM was 112.7 ± 36.7 ml. CMR-AL method overestimated LAV by 13.3 ± 21.8 ml (11.2%, p < 0.005) whereas 3D-CARTO and Echo-AL underestimated LAV by 8.3 ± 22.6 and 24.0 ± 27.6 ml respectively (8.7% and 20.0% respectively, p < 0.005). There was no significant difference between paroxysmal and persistent atrial fibrillation. CMR-AL and 3D-CARTO correlated and agreed well with CMR-MSM (r = 0.87 and 0.74, ICC = 0.80 and 0.77 respectively). However, Echo-AL had poor correlation and agreement with CMR-MSM (r = 0.66 and ICC = 0.48). Bland-Altman plots confirmed these findings. CMR-AL method may be used as an alternative to CMR-MSM, as it is non-invasive, rapid, and correlates well with CMR-MSM. LAV by different modalities should not be used interchangeably.

Normal left-atrial structure and function despite concentric left-ventricular remodelling in a cohort of patients with Anderson-Fabry disease

AIMS

Anderson-Fabry Disease (AFD) is an important cause of cardiomyopathy characterized by concentric left-ventricular hypertrophy (LVH). We evaluated the extent of left-atrial (LA) structural and functional remodelling in this group of patients given that LA remodelling is a marker of adverse outcomes in the presence of LVH.

METHODS AND RESULTS

Clinical profiles were obtained and cardiac MRI was performed in cohorts of patients with AFD (n = 31), healthy controls (n = 23), and a positive control cohort with known concentric remodelling and LVH (CR/H, n = 21). Of patients with AFD, 58% were on enzyme-replacement therapy (ERT), 84% were on renin-angiotensin system antagonism, and 65% were on statins. Despite a similar increase in LV mass index in the AFD when compared with the CR/H cohort, mean LA volumes for the AFD group were similar to those seen in the healthy control group. Following from this, we observed that the percentage contribution to LV stroke volume due to elastic/passive and active LA emptying was similar in the AFD and healthy control groups, while passive emptying was significantly lower in the CR/H group. The consequences of LVH in the AFD cohort were manifested in atrioventricular uncoupling, whereby the extent of elastic/passive and active LA emptying was not a function of the extent of longitudinal movement of the mitral annular plane, as it was in healthy control subjects.

CONCLUSION

Left-atrial structure and function were relatively normal in our cohort of patients with AFD, who were also judiciously treated with a contemporary strategy that includes renin-angiotensin system antagonism, statins, and ERT.

Impact of pulmonary vein antrum isolation on left atrial size and function in patients with atrial fibrillation

PURPOSE

The success of PVAI in eliminating AF has been proven; however, its impact on the LA remains uncertain. This study aimed to determine the impact of pulmonary vein antrum isolation (PVAI) on left atrial (LA) size and function in patients with atrial fibrillation (AF).

METHODS

Consecutive patients with AF were included (n = 206). Magnetic resonance imaging (MRI) was performed before and after PVAI in all patients. A subgroup (n = 52) underwent delayed enhancement MRI. Maximal LA volume (LAVmax) and minimal LA volume (LAVmin) were assessed by Simpson's rule. LA function was determined by calculating LA ejection fraction (LA EF). LA fibrosis was manually encircled and summed in the region of interest.

RESULTS

Single procedure success rate was 64 %. LAVmax decreased post-ablation in all patients (125.1 to 111.9 ml, p < 0.001). LAVmin only decreased in patients with a successful outcome post-ablation (65.6 to 58.8 ml, p < 0.001). As a result, LA EF only showed a marked reduction in patients with AF recurrences (42.7 % to 37.9 %, p < 0.001). Post-ablation LA fibrosis could be visualized in 77 % of patients who underwent delayed enhancement MRI (mean amount 1.4 cm(3)). LA fibrosis showed no correlation with the decrease in LAVmax or LA EF.

CONCLUSIONS

PVAI resulted in a reduction of LAVmax in all patients, indicating an effect of ablation induced fibrosis. LAVmin only decreased in patients with a successful outcome, indicating an effect of reverse atrial remodeling. As a result, LA function post-ablation was preserved in patients with a successful outcome and decreased in patients with AF recurrence.

2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design

This is a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation, developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology and the European Cardiac Arrhythmia Society (ECAS), and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). This is endorsed by the governing bodies of the ACC Foundation, the AHA, the ECAS, the EHRA, the STS, the APHRS, and the HRS.