Presence Of Left Atrial Enlargement Research Articles

Echocardiography and Electrocardiography in Detecting Atrial Cardiomyopathy: A Promising Path to Predicting Cardioembolic Strokes and Atrial Fibrillation

(1) Background: Atrial cardiomyopathy constitutes an intrinsically prothrombotic atrial substrate that may promote atrial fibrillation and thromboembolic events, especially stroke, independently of the arrhythmia. Atrial reservoir strain is the echocardiography marker with the most robust evidence supporting its prognostic utility. The main aim of this study is to identify atrial cardiomyopathy by investigating the association between left atrial dysfunction in echocardiography and P-wave abnormalities in the surface electrocardiogram. (2) Methods: This is a community-based, multicenter, prospective cohort study. A randomized sample of 100 patients at a high risk of developing atrial fibrillation were evaluated using diverse echocardiography imaging techniques, and a standard electrocardiogram. (3) Results: Significant left atrial dysfunction, expressed by a left atrial reservoir strain < 26%, showed a relationship with the dilation of the left atrium (p < 0.001), the left atrial ejection fraction < 50% (p < 0.001), the presence of advanced interatrial block (p = 0.032), P-wave voltage in lead I < 0.1 mV (p = 0.008), and MVP ECG score (p = 0.036). (4) Conclusions: A significant relationship was observed between left atrial dysfunction and the presence of left atrial enlargement and other electrocardiography markers; all of them are non-invasive biomarkers of atrial cardiomyopathy.

Longitudinal cardiac remodeling in collegiate American football players as assessed by echocardiography during their collegiate career.

Studies on the longitudinal effects of intense physical training on cardiac remodeling are limited, especially in American collegiate football players. College-level American football training will result in remodeling in a pattern consistent of a sport with moderate static and dynamic demands with increases in both wall and chamber sizes. We studied 85 American collegiate football players who underwent transthoracic echocardiogram (TTE) for asymptomatic or mild COVID-19-related illness and compared the changes in echo dimensions to their preparticipation screening TTE. Pre- and posttraining variables were compared using a paired t-test for normally distributed variables. Mean age was 19 years ± 1 and 61% of athletes were Black. Mean follow-up between TTEs was 21 ± 13 months. There was an increase in left atrial volume index (26.4 ± 5.5 to 32.8 ± 8.4 mL/m2 , p < .001), LV end diastolic diameter (5.13 ± 0.4 to 5.27 ± 0.4 cm, p = .003), basal RV diameter (3.28 ± 0.7 to 3.83 ± 0.5 cm, p = <.001), LV mass index (86.7 ± 15.3 to 90.1 ± 15.3, p = .015), and aortic root diameter (3.1 ± 0.4 to 3.2 ± 0.3 cm, p = .03) from pre- to posttraining, with a slightly greater magnitude in athletes with >2 years of training. Presence of left atrial enlargement (≥35 mL/m2 ) increased from 2.9% to 29% pre- to postparticipation in athletes with >2 years training. No significant changes in wall thickness, diastolic function, or right ventricular systolic function were observed. American football players college-level training was associated with increases in left and right ventricular chamber sizes, left atrial size, and aortic root diameter.

Hemodynamic and Clinical Determinants of Left Atrial Enlargement in Liver Transplant Candidates

New-onset heart failure is a frequent complication after orthotopic liver transplantation (OLT). Left atrial enlargement (LAE) may be a sign of occult left heart disease. Our primary objective was to determine invasive hemodynamic and clinical predictors of LAE and then investigate its effect on post-transplant outcomes. Of 609 subjects who received OLT between January 1, 2010, and October 1, 2018, 145 who underwent preoperative right-sided cardiac catheterization and transthoracic echocardiography were included. Seventy-eight subjects (54%) had pretransplant LAE. Those with LAE had significantly lower systemic vascular resistance with higher cardiac and stroke volume index (61.0 vs 51.7 ml/m2; p <0.001), but there was no difference in pulmonary artery wedge pressure. There was a linear relation between left atrial volume index and stroke volume index (R2=0.490, p<0.001), but not pulmonary artery wedge pressure. The presence of severe LAE was associated with a reduced likelihood (hazard ratio=0.26, p=0.033) of reaching the composite end point of new-onset systolic heart failure, heart failure hospitalization, or heart failure death within 12 months post-transplant. There was also a significant reduction in LAE after transplantation (p=0.013). In conclusion, LAE was common in OLT recipients and was more closely associated with stroke volume than left heart filling pressures. The presence of LAE was associated with a reduced likelihood of reaching composite outcomes and tended to regress after transplant.

Left Atrial Volume as A Parameter of The Ventricular Function in Patient with Non-Valvular Atrial Fibrillation

Background: Remodeling of the left atrium (LA)is a reflection of chronicity of the underlying, often occult cardiovascular disease. The presence of left atrial enlargement indicates clinically significant risk of adverse cardiovascular consequences for the patient. Left atrial volume provides a more sensitive assessment of left atrial enlargement, which is an important predictor of AF, providing incremental information beyond that afforded by the clinical risk factors and conventional M mode LA dimension. Objective: Assessment of left atrial volume as a parameter of ventricular function in patients with non-valvular atrial fibrillation. Patients and methods: The study was conducted on convenient sample of 50 patients with non-valvular AF and 50 normal control group who presented to Damietta Cardiology Center Outpatient Echocardiography Laboratory for a resting transthoracic study.The eligible patients were adults aged from 26 to 67 years, who had no history of pacemaker implantation, valvular heart disease (except mild degree), congenital heart disease and ischemic or dilated cardiomyopathy. Results: our study revealed that there was a strong direct significant graded relationship between the severity of diastolic dysfunction and left atrial volume index (LAVI) in patients of non-valvular AF. There was limited significance regarding Tei index and global longitudinal strain (GLS). Therefore, LAVI can be considered a sensitive and specific echocardiographic indicator for left ventricular diastolic dysfunction. We can consider LAVI the A1c of the heart. Conclusion: Diastolic dysfunction in non-valvular AF patient can be assessed using LAVI with limited significance of Tei index and GLS. Regarding systolic function in those patients, it can be assessed using GLS as it is considered sensitive index of early systolic dysfunction.

Distribution and area of low voltage and dense scar zones and their relation to left atrial enlargement in ablation-naïve patients with paroxysmal atrial fibrillation

There is paucity of studies correlating the left atrial (LA) dilation and the LA total and abnormal voltage areas in patients with atrial fi brillation (AF). We sought to determine the area of LA and its segments by high-density mapping in patients with paroxysmal AF, and to correlate the LA dilation defi ned by echocardiography with the total and the abnormal LA areas. Material and Methods. Retrospective study of patients with paroxysmal AF and pulmonary vein isolation proceeded by high-density mapping in sinus rhythm. All had transthoracic echocardiography and LA dilation, if present, was graded as mild/moderate-severe. LA voltage was defi ned as low (&lt; 0.5 mV) or scar (&lt; 0.1 mV). The LA was divided in 5 segments and the total and segmental area, low voltage area and scar area were measured. Data were presented as mean ± SD or median and interquartile interval (25-75%) depending on normality of distribution. Shapiro-Wilk test, Spearman T correlation, Kruskal-Wallis, and ANOVA analysis were used. A p-value &lt; 0.05 was considered significant. Results. Sixty-seven patients (66% males) were studied. LA enlargement was present in 58% (mild enlargement in 39%, moderate/severe in 19%). Low voltage and scar areas were found in both groups with and without LA dilation. Moderate correlation was found between the percentage of abnormal area and the degree of LA dilation (none vs mild vs moderate/severe), rho = 0.44, p = 0.0002. In patients with non-dilated LA the mean total LA area was 100.4 ± 17 cm2 and the abnormal area was &lt; 10% (9.9%, 6.2-14.8%), with barely detectable scar. In patients with LA enlargement the total area was approximately 10% larger (109.8 cm2, 100.9-123.8 cm2), however the abnormal area was almost doubled (17.1%, 11.1-26.8%), and there were small yet measurable dense scar areas. Conclusions. Low voltage LA areas &lt; 0.5 mV were found universally by high-density mapping in patients with paroxysmal AF, irrespective of the presence of LA enlargement. However, only patients with LA enlargement had measurable scar areas. The total abnormal area correlated moderately with the degree of LA dilation defi ned by echocardiography.

AIUM Practice Parameter for the Performance of Point-of-Care Ultrasound Examinations.

AIUM Practice Parameter for the Performance of Point-of-Care Ultrasound Examinations.

Prevalence of atrial fibrillation with insertable cardiac monitors in cryptogenic stroke: A single-center experience

BackgroundThe use of insertable cardiac monitors (ICM) has increased the rate of detection of atrial fibrillation (AF) among cryptogenic stroke (CS) patients. We describe a single-center experience for AF detection among CS patients receiving ICMs upon discharge after the index stroke event and attempt to identify predictors for AF detection. MethodsFrom April 2014 to October 2017, patients receiving ICMs for CS who underwent >60 days of monitoring were reviewed. Chronic underlying medical illnesses, presence of left atrial enlargement (LAE) on echocardiography, and PR interval on admission electrocardiogram were assessed as predictors of AF detection. ResultsA total of 234 patients (median age 72 [61, 78] years, 45% women) met inclusion criteria and were followed for a median of 536 [282, 848] days. Among studied patients, 68 patients (29%) were found to have AF at a median of 94.5 [16, 239] days from ICM placement. CS patients with AF were significantly older (p < 0.001), and there was a significantly higher proportion of women (p = 0.003) when compared to CS patients without AF. Neither presence of LAE nor prolonged PR interval was predictive of AF detection. ConclusionAlmost one-third of CS patients monitored with an ICM were found to have previously undiagnosed AF. CS patients found to have AF were older and more commonly women. Prospective studies are needed to better identify predictors for early AF among the broader population of all CS patients.

Left Atrial Size and Left Ventricular Mass Index in Hypertensive Patients

Background: This study was conducted with the objective of evaluation of the occurrence of left atrial enlargement (LAE) in hypertensive patients and its relationship with left ventricular mass index (LVMI).Methods: This single centre study was carried out at the Manmohan Cardiothoracic Vascular and Transplant Center, where total of 99 patients with hypertension who had left ventricular hypertrophy on echocardiography defined by left ventricular septal wall thickness &gt; 9mm for female and &gt;10 mm for male, were selected from May 2015 to August 2015.Results: In the study, the left atrium was enlarged in 31% of the selected patients. A total of 44% of patients having left atrial enlargement had increased left ventricular mass index as well, while a positive correlation (r = 0.3) was observed between the left atrial size and the left ventricular mass index (p= 0.001). The mean Left Ventricular Mass Index was 98 ± 32.7 g/m2 as compared to 115.34 ± 40.2 in patients with left atrial enlargement. The mean systolic blood pressure with left atrial enlargement was 146.70 ± 21.64 g/m2. Out of 99 patients, 80% of patients with left atrial enlargement had elevated body mass indexes, 48% had a history of smoking, 32% had diabetes mellitus, 22% had other complications of hypertension, and 12% had dyslipidemia.Conclusions: We concluded that the Left Atrial Size correlates significantly with the Left Ventricular Mass Index. In addition, the presence of left atrial enlargement should raise the suspicion of other metabolic derangements in hypertensive patients.Ann. Clin. Chem. Lab. Med. 2016:2(2);21-25

Point of care echocardiography in the emergency room

Purpose: Apical hypertrophic cardiomyopathy (AHM) is a variant of hypertrophic cardiomyopathy, involving nearly exclusively apex. It is very common among Asian patients, predominantly in Japanese, which is considered relatively benign condition. However, severe clinical manifestations, including sudden cardiac death, severe arrhythmias and apical infarction have been described in case reports. The electrocardiographic changes (giant negative T waves) and associated symptoms (chest pain, palpitations, dyspnea...) often present as acute coronary sindromes. AHM diagnosis is based on the demonstration of myocardial hypertrophy in the apical region of the left ventricle, usually by echocardiography with classical image “ace of spades”, although in many cases the use of contrast necessary. We present a case of young patient admited at ER with palpitations. Material & Methods: The most frequent morbid events in Eriksson et al study of AHM were atrial fibrillation (AF), probably related to left atrial enlargement and impaired LV relaxation. It is prudent to also closely examine the heart on bedside emergency echocardiography looking for the presence of left atrial enlargement. Results: 37 year old male, with no significant medical history, was admitted to the ER by palpitations. The electrocardiogram showed AF with deep, negative T-waves in leads V3-V6. Bedside emergency echocardiography (BEE) initially performed to look for left atrial enlargement, revealed apical hypertrophy, with apical cavity obliteration during systole. These findings were confirmed by contrast ecocardiography. The patient was diagnosed with AHM (Yamaguchi's syndrome) and started on beta-blocker therapy. Conclusion: In this case, BEE helped to identify an AHM. It was the findings on emergency ultrasound, performed and interpreted by EPs, that helped to identify the correct diagnosis and prompted the appropriate consultations to cardiologist, with a final diagnostic of AHM.

The Influence of Left Atrial Enlargement on the Relationship between Atrial Fibrillation and Stroke

Left atrial enlargement (LAE) is independently associated with an increased risk of stroke and atrial fibrillation (AF). The combination of both LAE and AF possibly increases the risk of stroke beyond that observed with AF. This analysis included 4572 (43% men, 95% white) participants from the Cardiovascular Health Study. LAE was defined using transthoracic echocardiographic 2-dimensional M-mode measurements of the left atrial diameter using sex-specific cut-points (men: ≥4.1 cm, women: ≥3.9 cm). AF cases were identified during the initial study electrocardiogram or by self-reported history. We examined the association between baseline AF and incident ischemic stroke stratified by the presence of LAE. Incident cases of ischemic stroke were identified by adjudication of medical records, including hospitalization data, through December 31, 2010. At baseline, a total of 253 (5.5%) participants had AF and 1947 (43%) had LAE. Participants with AF (n = 163, 64%) were more likely to have LAE than those without AF (n = 1784, 41%; P < .001). Over a median follow-up of 13 years, 739 (16%) ischemic stroke events were identified. Both AF (hazard ratio [HR] = 2.12, 95% confidence interval [CI] = 1.64-2.74) and left atrial diameter (per 1-cm increase: HR = 1.14, 95% CI = 1.01-1.28) were associated with an increased risk for ischemic stroke. The association between AF and ischemic stroke was not modified by the presence of LAE (LAE: HR = 2.13, 95% CI = 1.42-3.19; no LAE: HR = 1.91, 95% CI = 1.36-2.68; P interaction = .86). Our results suggest that echocardiographic LAE does not modify the stroke risk observed with AF.

A Simple Derived Prediction Score for theIdentification of an Elevated PulmonaryArtery Wedge Pressure Using Precatheterization Clinical Data in Patients Referred to a Pulmonary Hypertension Center.

One of the foremost diagnostic challenges in clinical pulmonary hypertension is discriminating between pulmonary arterial hypertension (group 1) and heart failure with preserved ejection fraction (group 2.2). Group 2.2 is defined as a normal left ventricular ejection fraction (> 50%) and a pulmonary arterial wedge pressure (PAWP) > 15mmHg. We aimed to determine whether patient history, demographics, and noninvasive measures could predict PAWP before to right heart catheterization. Data were prospectively collected on 350 consecutive patients at a single tertiary care medical center; of these patients, 151 met criteria for entry into our study (88 in group 1 and 63 in group 2.2). Data included historical features, demographics, and results of a transthoracic echocardiogram. A multivariate regression model was developed to predict PAWP > 15mmHg. Univariate predictors of PAWP > 15mmHg included older age, higher BMI and weight, systemic systolic BP and pulse pressure, more features of the metabolic syndrome, presence of hypertension and left atrial enlargement, absence of right ventricular enlargement, and lower glomerular filtration rate and 6-min walk distance. The optimal model for predicting PAWP > 15mmHg was composed of age (> 68 years), BMI (> 30kg/m(2)), absence of right ventricular enlargement, and presence of left atrial enlargement (area under the curve, 0.779). Clinical characteristics obtained before diagnostic right heart catheterization accurately predict the probability of elevation of PAWP > 15mmHg in patients with preserved ejection fraction. These combined clinical characteristics can be used a priori to predict the likelihood of group 2.2 pulmonary hypertension.

The Role of Echocardiography in Hypertension

Systemic hypertension leads to hypertensive heart disease. Left ventricular hypertrophy (LVH) is a result of chronic systemic pressure overload. Although systolic function is preserved in early stages, it deteriorates gradually. LVH is symmetrical in hypertension. LVH causes different changes in longitudinal, radial and circumferential mechanics in patients with hypertensive patients. Longitudinal strain is significantly decreased, while radial strain is increased. Left atrial (LA) dilatation is commonly seen in hypertensive patients. Also, LA strain values are lower in hypertensive patients when compared to normal, irrespective to the presence of LA enlargement or LVH. In addition, LVH may cause early sub clinical RV dysfunction as well. According to the most recent guidelines, it is stated that initiation or monitoring the response to antihypertensive response is based on clinical parameters. However, periodic evaluation of cardiac function and morphology by echocardiography are necessary because of the progressive characteristics of hypertensive cardiomyopathy.

Factors Associated with Left Atrial Enlargement in Patients with Anemia Caused by Uterine Myoma

Background: Uterine myoma (UM) is common among female gender, and it often causes anemia. Left atrial enlargement (LAE) is commonly detected in patients with anemia as well as caused by uterine myoma. Therefore, this study was aimed to investigate the clinical implications of LAE and its associating factors in patients with anemia caused by UM. Methods: This is a retrospective observational cross sectional study and it considered 139 female patients with UM who had undergone preoperative echocardiography. Patients were sorted into 2 groups according to the presence of LAE (n=60) or not (n=79). LAE was defined as LA volume index (LAVI) was 35 ml/m2 or more. Results: Patients with LAE (LAVI: 41.0 ± 5.3 ml/m2) showed larger left ventricular (LV) dimension and increased LV mass index (LVMI) than patients without LAE (LAVI: 27.9 ± 3.9 ml/m2). Patients with LAE were older, showed slower heart rate (HR) and further decreased level of hemoglobin. Older age, slower HR, level of hemoglobin, larger LV, increased LMI, E/E’, right ventricular systolic pressure and decreased S’ velocity were shown to be correlated with increased LAVI. Among them, older age (OR: 1.119, 95% CI: 1.014-1.236, p=0.026) and slower HR (OR: 0.926, 95% CI: 0.878-0.977, p=0.005) were independently associated with LAE in patients with anemia caused by UM. Conclusion: LAE was often noticed in patients with anemia caused by UM and older age and slower HR were seemed to be its associating factor.

Abstract W P182: Left Atrial Volume as a Clinical Predictor for Atrial Fibrillation Detection in Cryptogenic Stroke: A Retrospective Analysis

Background: Detection of paroxysmal atrial fibrillation (PAF) after cryptogenic stroke has a major impact on secondary stroke prevention. Identifying clinical predictors to obtain a higher detection rate is necessary. There is an unclear association between left atrial enlargement (LAE) and PAF. Our goal was to determine the yield of 30-day Holter monitoring in patients with left atrial enlargement following acute ischemic stroke. Methods: We retrospectively identified patients with acute ischemic stroke from November 2012 to June 2014 who had an echocardiogram done and a 30-day holter monitor on discharge. Demographics, medical history, clinical/laboratory data, echocardiographic features and holter monitor detected events were collected. Moderate to severe LAE was defined as left atrial volume index (LAVI) &gt;35 cc/m2 on trans-thoracic echocardiogram. Patients were divided into two groups based on LAVI &gt;35 cc/m2; thirty day holter monitoring results were retrieved in each group. Along with paroxysmal atrial fibrillation, detection of other supraventricular arrhythmias associated with subsequent development of PAF (i.e., supraventricular tachycardia (SVT) and atrial ectopy) was compared between the groups. Categorical variables were analyzed with Fischer’s exact test and continuous variables using independent sample T-test. Results: 136 patients met our inclusion criteria, of which 76 (55.9%) completed 30 days of monitoring. Moderate to severe LAE was identified in 30 of 76 patients (39.5%). PAF was detected in 4 patients (5.3%). However, PAF was more likely in patients with LAE (13.3% vs 0%, p= 0.21). Detection of any PAF, SVT and atrial ectopy was more likely in patients with LAE (30% vs 6.5%, p= 0.009). Demographics, medical history, clinical and laboratory variables did not differ between patients with and without LAE. Conclusions: In our cohort, the presence of LAE increased the yield of PAF on 30-day holter monitoring. Supraventricular arrhythmias historically associated with subsequent development of atrial fibrillation were more likely in ischemic stroke patients with LAE.

Score for atrial fibrillation detection in acute stroke and transient ischemic attack patients in a Brazilian population: The acute stroke atrial fibrillation scoring system

OBJECTIVE:Atrial fibrillation is a common arrhythmia that increases the risk of stroke by four- to five-fold. We aimed to establish a profile of patients with atrial fibrillation from a population of patients admitted with acute ischemic stroke or transient ischemic attack using clinical and echocardiographic findings.METHODS:We evaluated patients consecutively admitted to a tertiary hospital with acute ischemic stroke or transient ischemic attack. Subjects were divided into an original set (admissions from May 2009 to October 2010) and a validation set (admissions from November 2010 to April 2013). The study was designed as a cohort, with clinical and echocardiographic findings compared between patients with and without atrial fibrillation. A multivariable model was built, and independent predictive factors were used to produce a predictive grading score for atrial fibrillation (Acute Stroke AF Score-ASAS).RESULTS:A total of 257 patients were evaluated from May 2009 to October 2010 and included in the original set. Atrial fibrillation was diagnosed in 17.5% of these patients. Significant predictors of atrial fibrillation in the multivariate analysis included age, National Institutes of Health Stroke Scores, and the presence of left atrial enlargement. These predictors were used in the final logistic model. For this model, the area under the receiver operating characteristic curve was 0.79. The score derived from the logistic regression analysis was The model developed from the original data set was then applied to the validation data set, showing the preserved discriminatory ability of the model (c statistic = 0.76).CONCLUSIONS:Our risk score suggests that the individual risk for atrial fibrillation in patients with acute ischemic stroke can be assessed using simple data, including age, National Institutes of Health Stroke Scores at admission, and the presence of left atrial enlargement.

Correlation of Echocardiographic Left Atrial Abnormality With Myocardial Ischemia During Myocardial Perfusion Assessment in Patients With Left Bundle Branch Block

Left atrial (LA) abnormality, an easily quantifiable parameter of left ventricular (LV) diastolic dysfunction, has been associated with cardiovascular risk. Because during myocardial perfusion study (MPS), the abnormal LV activation pattern in patients with left bundle branch block (LBBB) frequently induces perfusion defects, a clinical correlate of early myocardial ischemia such as LA enlargement could alleviate some of these inherent challenges. We prospectively studied 144 consecutive patients with LBBB who underwent MPS after screening for electrocardiographic and echocardiographic LA enlargement over a 6-month period. Of those, 114 had a positive MPS result. We found that LA size (p <0.0001) and P-wave duration (p = 0.001) were significantly increased in patients as the severity of the defects increased on MPS, whereas LV ejection fraction was decrementally reduced (p = 0.001). Importantly, LA size (≥43.5 mm; sensitivity 70%, specificity 89%) and P-wave duration (≥135 milliseconds; sensitivity 63%, specificity 90%) were greatest when the MPS defect was severe. In conclusion, the presence of LA enlargement appears significantly correlated with myocardial ischemia among patients with LBBB and could therefore assist during MPS interpretation among patients in whom MPS interpretation could be challenging.

Risk factors for incident atrial fibrillation with and without left atrial enlargement in women

Left atrial (LA) enlargement facilitates induction and/or maintenance of atrial fibrillation (AF). However, little is known about risk factors for AF with normal LA size. We prospectively followed 34713 initially healthy women for incident AF. Information on echocardiographic LA size at first AF diagnosis was abstracted from medical charts during AF confirmation. LA enlargement was defined as LA diameter >40 mm. Using a competing risk approach, we constructed Cox proportional-hazards models to calculate hazard ratios (HR) and 95% confidence intervals (CI) of risk factors for incident AF with and without LA enlargement, respectively. Among 796 women with incident AF and available LA size, 328 (41%) had LA enlargement. In multivariable competing risk models, the relationship between age and incident AF was stronger in those with (HR 1.12, 95% CI 1.10-1.14) versus without (HR 1.08, 95% CI 1.06-1.09) LA enlargement (p for difference <0.0001). Body weight was associated with AF only in the presence of LA enlargement (HR per 10 kg 1.34, 95% CI 1.26-1.43; versus 1.07, 95% CI 0.998-1.14, p for difference<0.0001). Hypertension and height were significantly associated with AF both in the presence (HR 1.99, 95% CI 1.49-2.65; and HR per 10 cm 1.36, 95% CI 1.13-1.63) and absence (1.55, 1.25-1.92 and 1.29, 1.10-1.50) of LA enlargement (p for difference 0.17 and 0.66, respectively). These data suggest that LA enlargement explains much of the increased AF risk associated with obesity and age. In contrast, height and hypertension appear to also influence AF risk through other mechanisms besides LA enlargement.

Left atrial myxoma—influence of tumour size on electrocardiographic findings

ObjectiveThe data of 51 patients (33 females) who underwent excision of left atrial (LA) myxoma were retrospectively reviewed for correlation of tumour size and electrocardiographic (ECG) findings. Methods and resultsMean age was 39.1 ± 15 years (range 9–53 years). The LA enlargement (LAE) on ECG was defined by standard criteria. The LAE in ECG in these patients did not correlate with echocardiographic LA dimensions or with the degree of left ventricular (LV) inflow obstruction. But it was found that the presence of LAE in ECG predicted maximum tumour dimension of >5 cm and correlated with the degree of mitral regurgitation (MR). The LAE in ECG disappeared following surgery in 87.5% of patients. ConclusionThe LA enlargement on ECG in a patient with LA myxoma signifies larger tumour size or the presence of significant MR but is not necessarily associated with an increased LA size or LV inflow obstruction.

Fetal Cardiac Troponin Isoforms Rescue the Increased Ca2+ Sensitivity Produced by a Novel Double Deletion in Cardiac Troponin T Linked to Restrictive Cardiomyopathy: A CLINICAL, GENETIC, AND FUNCTIONAL APPROACH

A novel double deletion in cardiac troponin T (cTnT) of two highly conserved amino acids (Asn-100 and Glu-101) was found in a restrictive cardiomyopathic (RCM) pediatric patient. Clinical evaluation revealed the presence of left atrial enlargement and marked left ventricle diastolic dysfunction. The explanted heart examined by electron microscopy revealed myofibrillar disarray and mild fibrosis. Pedigree analysis established that this mutation arose de novo. The patient tested negative for six other sarcomeric genes. The single and double recombinant cTnT mutants were generated, and their functional consequences were analyzed in porcine skinned cardiac muscle. In the adult Tn environment (cTnT3 + cardiac troponin I), the single cTnT3-ΔN100 and cTnT3-ΔE101 mutations had opposing effects on the Ca(2+) sensitivity of force development compared with WT, whereas the double deletion cTnT3-ΔN100/ΔE101 increased the Ca(2+) sensitivity + 0.19 pCa units. In addition, cTnT3-ΔN100/ΔE101 decreased the cooperativity of force development, suggesting alterations in intrafilament protein-protein interactions. In the fetal Tn environment, (cTnT1 + slow skeletal troponin I), the single (cTnT1-ΔN110) and double (cTnT1-ΔN110/ΔE111) deletions did not change the Ca(2+) sensitivity compared with control. To recreate the patient's heterozygous genotype, we performed a reconstituted ATPase activity assay. Thin filaments containing 50:50 cTnT3-ΔN100/ΔE101:cTnT3-WT also increased the myofilament Ca(2+) sensitivity compared with WT. Co-sedimentation of thin filament proteins indicated that no significant changes occurred in the binding of Tn containing the RCM cTnT mutation to actin-Tm. This report reveals the protective role of Tn fetal isoforms as they rescue the increased Ca(2+) sensitivity produced by a cTnT-RCM mutation and may account for the lack of lethality during gestation.

Fetal Cardiac Troponin Isoforms Rescue the Increased Ca 2+ Sensitivity Produced by a Novel Double Deletion in Cardiac Troponin T Linked to Restrictive Cardiomyopathy

A novel double deletion in cardiac troponin T (cTnT) of two highly conserved amino acids (N100 and E101) was found in a restrictive cardiomyopathic (RCM) pediatric patient. Clinical evaluation revealed the presence of left atrial enlargement and marked left ventricle diastolic dysfunction. The explanted heart examined by electron microscopy revealed myofibrillar disarray and mild fibrosis. Pedigree analysis established that this mutation arose de novo. Functional studies were carried out in the fetal (cTnT1 + slow skeletal troponin I (ssTnI)) and adult (cTnT3 and cardiac TnI (cTnI)) troponin (Tn) backgrounds. The single and double cTnT mutants (cTnT3-ΔN100, cTnT3-ΔE101, cTnT3-ΔN100/ΔE101, cTnT1-ΔN110, cTnT1-ΔE111 and cTnT1-ΔN110/ΔE111) were generated and their functional effects analyzed in skinned cardiac muscle. In the adult Tn enviroment, the single cTnT3-ΔN100 and cTnT3-ΔE101 mutations in the presence of cTnI caused opposing changes on the Ca2+ sensitivity of force development compared to WT with respective values of +0.29 and −0.28 pCa units; yet the cTnT3-ΔN100/ΔE101 mutation shifted the Ca2+ sensitivity to the left (+ 0.19 pCa units). In addition, cTnT3-ΔN100/ΔE101 decreased cooperativity of force development suggesting altered intra-filament protein-protein interactions. In the fetal Tn eviroment, the single (cTnT1-ΔN110) and double (cTnT1-ΔN110/ΔE111) deletion in the presence of ssTnI did not show any change in the Ca2+ sensitivity compared to its control. In an attempt to recreate the patient's heterozygous genotype we performed a reconstituted ATPase activity assay. Thin filaments containing 50:50% of cTnT3-ΔN100/ΔE101:cTnT3-WT also showed increased Ca2+ sensitivity of the myofilament compared to the WT. This report reveals the protective role of the Tn fetal isoforms since they rescue the increased Ca2+ sensitivity produced by a cTnT-RCM mutation and may account for this mutation not being lethal during gestation.