QT prolongation and variability: new ECG signs of atrial potentials dispersion before atrial fibrillation onset.

AIMS: QT interval may be considered an indirect marker of atrial repolarization. Aim of our study was to verify if QT interval variations precede the onset of atrial fibrillation (AF). METHODS: We analyzed 21 AF onsets recorded at 24-h Holter ECG. Triggering supraventricular extrabeats (TSVEB) were identified and matched to nontriggering supraventricular extrabeats (NTSVEB) with the same prematurity index. QT and QTc intervals and their variability (max-min QT interval) were measured in the 10 beats preceding TSVEB and NTSVEB. RESULTS: QTc (470.1 ±â€Š56.7 vs. 436.7 ±â€Š25.6 ms; P = 0.006), QT (36.8 ±â€Š13.1 vs. 21.1 ±â€Š10.1 ms; P = 0.001) and QTc variability (41.5 ±â€Š15.8 vs. 23.1 ±â€Š11.9; P = 0.001) significantly varied between TSVEB and NTSVEB. By stratifying AF onsets in vagal (n = 10) and adrenergic (n = 11) according to Heart Rate Variability, significant differences emerged concerning QT (35.20 ±â€Š16.48 vs. 22.70 ±â€Š10.23 ms, P = 0.006) and QTc variability (39.30 ±â€Š18.32 vs. 25.60 ±â€Š12.91 ms, P = 0.029) for vagal onsets and QTc (477.73 ±â€Š57.50 vs. 438.00 ±â€Š28.55 ms, P = 0.045), QT (38.36 ±â€Š9.79 vs. 19.73 ±â€Š10.21 ms, P = 0.005) and QTc variability (43.55 ±â€Š13.72 vs. 20.82 ±â€Š11.01 ms, P = 0.004) for adrenergic onsets. By stratifying AF onsets in type I (n = 7) or II (n = 14) according to a cycle length variation in the 30 s before the onset greater or smaller than 10% respectively, significant differences were noted concerning QTc (477.73 ±â€Š57.50 vs. 438 ±â€Š28.55 ms, P = 0.045), QT (43.55 ±â€Š13.72 vs. 20.82 ±â€Š11.01 ms, P = 0.005) and QTc variability (43.55 ±â€Š13.72 vs. 20.82 ±â€Š11.01 ms, P = 0.004) in type I and QT (35.20 ±â€Š16.48 vs. 22.70 ±â€Š10.23 ms, P = 0.006) and QTc variability (39.30 ±â€Š18.32 vs. 25.60 ±â€Š12.91 ms, P = 0.029) in type II onsets. CONCLUSION: Prolongation and QT variability represent a relevant substrate marker in the genesis of AF, independently of the trigger type.

Frequent premature atrial contractions impair left atrial contractile function and promote adverse left atrial remodeling.

OBJECTIVES: This study assessed if frequent premature atrial contractions (PACs) were associated with decreased left atrial (LA) strain and adverse remodeling. BACKGROUND: Left atrial dysfunction and enlargement increases risk of stroke. If frequent PACs cause LA dysfunction and remodeling, PAC suppressive therapy may be beneficial. METHODS: Inclusion criteria were age ≥18 years and sinus rhythm. Exclusion criteria were atrial fibrillation or any etiology for LA enlargement. Hundred and thirty-two patients with frequent PACs (≥100/24 hours) by Holter were matched to controls. Speckle tracking strain of the left atrium was performed from the 4-chamber view. Strain measurements were LA peak contractile, reservoir and conduit strain and strain rates. RESULTS: In the frequent PAC vs control group, PACs were more frequent (1959 ± 3796 vs 28 ± 25/24 hours, P < .0001). LA peak contractile strain was reduced in the group with frequent PACs vs controls (-7.85 ± 4.12% vs -9.33 ± 4.45%, P = .006). LA peak late negative contractile strain rate was less negative in the frequent PAC vs control group (-0.63 ± 0.27 s-1 vs -0.69 ± 0.32 s-1 , P = .051). LA reservoir and conduit strain and strain rates did not differ. LA volume index (LAVI) was larger in the frequent PAC vs control group (26.6 ± 7.8 vs 24.6 ± 8.8 mL/m2 , P < .05). Frequent PACs were an independent predictor of reduced LA peak contractile strain and reduced LA peak late negative contractile strain rate. CONCLUSIONS: Patients with frequent PACs have reduced LA peak contractile strain and strain rates and larger LAVI compared to controls. Frequent PACs are an independent predictor of reduced LA peak contractile strain and strain rate. These findings support the hypothesis that frequent PACs impair LA contractile function and promote adverse LA remodeling.

Role of the burden of premature atrial contractions during the blanking period following second-generation cryoballoon ablation in predicting late recurrences of atrial arrhythmias.

PURPOSE: Recent data suggests that high burden of premature atrial complexes after pulmonary vein isolation predicts recurrences of atrial arrhythmias. The present study sought to assess the role of premature atrial complexes burden in predicting atrial arrhythmias recurrences in patients with atrial fibrillation (AF) who have undergone second-generation cryoballoon ablation (CB-Adv). METHODS: Consecutive patients with drug-resistant paroxysmal atrial fibrillation who underwent pulmonary vein isolation using CB-Adv technology as the index procedure were retrospectively included. Twenty-four-hour Holter recordings were performed for every patient. Based on previously published data, a burden of more than 76 premature atrial complexes per day was considered as being high. RESULTS: One hundred and seven patients were included in the analysis. The recurrence rate among the group of patients with more than 76 premature atrial complexes per day was significantly higher compared with the group with a lower burden of premature atrial complexes (47.5 vs 11.9%, respectively; p < 0.001). In the multivariate analysis, the documentation of more than 76 premature atrial complexes per day registered at 1 month and at the end of the blanking period, predicted late recurrence of atrial arrhythmias. CONCLUSIONS: Frequent premature atrial complexes in the early stages after CB-Adv ablation strongly predict late recurrences of atrial arrhythmias.

Supraventricular premature beats and risk of new-onset atrial fibrillation in coronary artery disease.

INTRODUCTION: The significance of premature atrial contraction (PAC) count and supraventricular runs (SVR) for the risk of development of new-onset atrial fibrillation (AF) in patients with coronary artery disease (CAD) is not well established. METHODS: The Innovation to Reduce Cardiovascular Complications of Diabetes at the Intersection (ARTEMIS) study cohort consisted of 1,946 patients with CAD who underwent clinical and echocardiographic examinations, 24-hour ambulatory ECG monitoring, and laboratory tests. After excluding patients who were not in sinus rhythm at baseline or were lost from the follow-up, the present study included 1,710 patients. SVR was defined as at least four PACs in a row with a duration <30 seconds. RESULTS: During a follow-up for an average 5.6 ± 1.5 years, new-onset AF was identified in 143 (8.4%) patients. In the univariate analysis, both SVR and PAC count were associated with the development of new-onset AF. When SVR and PAC count were adjusted with the established AF risk markers of the modified CHARGE-AF model in the Cox multivariate regression analysis, both parameters remained significant predictors of the occurrence of new-onset AF (HR = 2.529, 95 % CI = 1.763-3.628, P ˂ 0.001 and HR = 8.139 for ≥1,409 PACs [the fourth quartile] vs. ≤507 PACs [the first quartile], 95 % CI = 3.967-16.696, P ˂ 0.001, respectively). Together these parameters improved the C-index of the established AF risk model from 0.649 to 0.718, P < 0.001. CONCLUSION: Including SVR and PAC count to the established AF risk model improves the discrimination accuracy in predicting AF in patients with CAD.

The Assessment of Atrial Electromechanical Delay in Patients With Acromegaly.

BACKGROUND: We aimed to evaluate whether atrial electromechanical delay (AEMD) measured by tissue Doppler imaging (TDI), which is an indicator for structural and electrical remodelling of the atria, is prolonged in patients with active or inactive acromegaly, or both, compared with a control group. METHODS: A total of 34 patients with acromegaly (18 active/16 inactive) and 35 patients as a control group were enrolled. Both intra- and inter-AEMD were calculated by TDI. The correlation between clinical variables and AEMD were analyzed. RESULTS: Both inter-AEMD and right and left intra-AEMD were prolonged in patients with acromegaly compared with the control group (P < 0.001, P < 0.001, and P = 0.004, respectively). Also, patients with active acromegaly showed higher inter-AEMD and right intra-AEMD compared with patients with inactive acromegaly (P < 0.05). There was no significant difference in left intra-AEMD between patients with active acromegaly and those with inactive acromegaly (P = 0.977). The growth hormone and insulin-like growth factor (IGF-1) levels positively correlated with inter-AEMD (r = 0.577; P < 0.001; r = 0.614; P < 0.001, respectively). Additionally, we found that inter-AEMD was significantly and positively correlated with relationship between maximal values of passive mitral inflow (E, PW-Doppler) and lateral early diastolic mitral annular velocities (e', TDI) (r = 0.316; P = 0.008). Only the serum IGF-1 level was independently associated with inter-AEMD in multivariate linear regression analysis (ß = 0.500; P = 0.011). CONCLUSIONS: Our study findings showed that both inter- and intra-AEMD are prolonged in patients with acromegaly. Also, AEMD was observed to be more prolonged in patients with active acromegaly than in those with inactive acromegaly. IGF-1 was an independent predictor of inter- AEMD in patients with acromegaly. Being a noninvasive, inexpensive, and simple technique, AEMD may be used as an indicator for atrial electrical and structural remodelling in patients with acromegaly.

Doppler echocardiographic isovolumetric time intervals in diagnosis of fetal blocked atrial bigeminy and 2:1 atrioventricular block.

OBJECTIVE: To distinguish between blocked atrial bigeminy (BB) and incomplete atrioventricular block with 2:1 conduction (2:1 AVB) can be very difficult, especially in the mid-term fetus. Making a correct diagnosis has important clinical implications, as their prognosis and management differ markedly. Our objective was to investigate whether analysis of isovolumetric time intervals could improve Doppler echocardiography in differentiating these conditions. METHODS: Sixteen fetuses with sustained BB or isolated 2:1 AVB, diagnosed at our tertiary center from 2002 to 2012, were reviewed retrospectively. Doppler recordings of left ventricular in- and outflow, including mitral and aortic valve movements, were used to measure isovolumetric contraction (ICT) and relaxation (IRT) time intervals. ICT reference values obtained from 104 normal pregnancies were used for comparison. RESULTS: Ten fetuses had BB and six 2:1 AVB. Five of the AVB cases were anti-Ro antibody positive and one had long QT syndrome (LQTS). ICT was systematically shorter in BB than in antibody-mediated 2:1 AVB. Nine of 10 cases with BB had an ICT below -2 SD and the five with antibody-mediated 2:1 AVB had values at or above +2 SD. All 15 fetuses with either BB or antibody-mediated AVB had an IRT of < 70 ms, as opposed to a markedly prolonged IRT (105 ms) in the LQTS case. CONCLUSION: Measurement of ICT can improve the differential diagnosis between BB and antibody-mediated 2:1 AVB. Fetuses with BB or antibody-mediated AVB are unlikely to have IRT measurements exceeding 70 ms and, when this is observed, LQTS should be considered a more likely diagnosis.

Hepatic venous Doppler in the evaluation of fetal extrasystoles.

OBJECTIVES: To evaluate the use of fetal hepatic venous Doppler in the diagnosis of fetal extrasystoles, to estimate the prevalence and persistence of extra atrial and ventricular heart beats throughout pregnancy, labor and delivery, and to estimate the frequency of coexisting congenital heart disease. METHODS: This was a retrospective study of 256 singleton pregnancies attending our hospital as outpatients due to fetal extrasystoles. Hepatic venous Doppler and detailed fetal echocardiography were performed. Information on fetal heart rate patterns during labor and neonatal conditions was collected. Congenital heart malformations and the frequency and persistence of fetal extrasystoles were noted. RESULTS: On venous Doppler examination, 228 (89%) of the fetuses showed signs of supraventricular extrasystoles (SVES) and 28 (11%) had ventricular extrasystoles (VES). One fetus with SVES developed atrial flutter during pregnancy and another case developed supraventricular tachycardia postnatally. SVES persisted until labor and delivery in 28 (12.3%) fetuses and VES persisted in six (21.4%). In 31 of 34 (91.2%) fetuses with extrasystoles during labor and delivery, the conduction pattern normalized within 3 days. Five neonates were referred for evaluation by a pediatric cardiologist. Two cases had congenital heart disease. Extrasystoles persisted until labor and delivery more frequently in male fetuses (P < 0.0001). CONCLUSION: Hepatic venous Doppler can differentiate between SVES and VES. Despite being the more uncommon of the two, VES persists throughout pregnancy more often. Our results strongly support the suggestion that extrasystoles are a benign finding, with very few cases developing tachycardia or having a coexisting congenital heart malformation.

Correlation of heart rate to body weight in apparently normal dogs.

OBJECTIVE: To evaluate the correlation between heart rate and body weight in the apparently healthy dog. ANIMALS: Sixty dogs weighing between 2 and 80 kg. METHODS: Heart rate was evaluated with a 24-h ambulatory electrocardiogram. Minimum, average, maximum heart rate, ventricular premature complex (VPC) number and supraventricular premature complex (SVC) number were tabulated for each dog. RESULTS: Minimum, maximum and average heart rate did not correlate to body weight. For all dogs, the median minimum heart rate was 42 bpm (beats per minute), median average heart rate was 73 bpm, and median maximum heart rate was 190. The median number of VPCs and SVC was zero. CONCLUSIONS: The present study does not support a correlation between heart rate and body weight in apparently healthy dogs.

ECG-edit function in multidetector-row computed tomography coronary arteriography for patients with arrhythmias.

BACKGROUND: ECG-gating is necessary for cardiac computed tomography, but is not suitable for arrhythmias, so the aim of this study was to evaluate the usefulness of the ECG-edit function for this purpose. METHODS AND RESULTS: Of 1,221 patients undergoing 64-row multidetector-row computed tomography coronary angiography (coronary MDCT), 123 patients (28 atrial fibrillation (Af), 39 premature atrial contractions (PAC), 42 premature ventricular contractions (PVC), 3 PAC + PVC, 10 sinus arrhythmias (SA), and a second-degree atrioventricular block (2 degrees AVB)) had arrhythmias necessitating the ECG-edit function. Short R-R interval was deleted and mid-diastolic phases were selected from the long R-R intervals using the "R+absolute time" method. In the present study, the reconstructed images were evaluated using a triple-grade scale A-C, representing excellent, acceptable, and unacceptable image quality. Image quality, categorized as A, B and C, respectively, was 50%, 36% and 14% for the 28 patients with Af; 56%, 36% and 8% for the 39 PAC patients, and 65%, 33% and 2% in the 42 PVC patients. None of the scans of the PAC + PVC, SA, and 2 degrees AVB patients was ranked as C. CONCLUSIONS: The ECG-edit function is useful for reconstructing coronary MDCT images in many arrhythmias, and provides clinically acceptable images in most cases.

Postnatal outcome of fetal bradycardia without significant cardiac abnormalities.

BACKGROUND: A heart rate <100 beats/min may be present in 5% of fetuses with arrhythmia. In this study, we sought to define the feasibility of in utero diagnosis of the underlying mechanisms and the postnatal outcome. METHODS: The types of fetal bradycardia were defined by fetal echocardiogram. Fetuses with transient sinus bradycardia were excluded. RESULTS: From 1995-2000, a total of 18 fetuses were found to have bradycardia. Postnatal 12-lead electrocardiograms made at least 3 times during follow-up confirmed the cardiac rhythm in all except those terminated during pregnancy. Sick sinus bradycardia was noted in 4 patients (22 %), of whom 1 had a positive family history and 2 received permanent pacemakers at age 4 and 5 years. Frequent nonconducted atrial premature beats or nonconducted atrial bigeminy or trigeminy were noted in 5 (28%). All of them revealed normal sinus rhythm after birth. Atrioventricular (AV) block was noted in 6 (33%), of whom 3 were terminated due to severe heart failure, and another 2 fetuses received permanent pacemaker implantation soon after birth. Only 1 fetus whose mother showed normal levels of C3 and C4 recovered at late gestation. Most importantly, 3 patients (17%) developed intermittent bradycardia (AV block) and ventricular tachycardia during the fetal stage. They were found to have long QT syndrome. Two of them died during early infancy. One received in utero propranolol and postnatal propranolol and nicorandil with satisfactory control. CONCLUSION: The mechanisms responsible for fetal bradycardia were diverse and could be characterized by fetal echocardiography. The prognosis was poor in those with long QT syndrome manifested as intermittent fetal bradycardia and tachycardia with AV dissociation.

[Analysis of mode of delivery in cases with fetal premature atrial contractions]. / Analiza sposobu ukonczenia ciazy w przypadkach nadkomorowych skurczów dodatkowych u plodu.

OBJECTIVE: Premature atrial contractions are common in obstetrical practise but there is little information available on recommended management and mode of delivery. DESIGN: The aim of the study was to describe our clinical experience in the management of fetal arrhythmia including the indications for certain time and way of labour. MATERIALS AND METHODS: 128 fetuses with diagnosed supraventricular arrhythmia described as atrial extrasystole were examined. They were divided into 3 main groups: group I (84 fetuses) with single PAC, group II (37 fetuses) with quantitatively significant arrhythmia or accompanied by another kind of arrhythmia and group III (7 fetuses) associated with extracardiac abnormalities. RESULTS: Among 128 fetuses with supraventricular arrhythmia, 44 cases (31%) required systematic monitoring. Quantitatively significant arrhythmia was recognized in 15 cases, blocked bigeminy (2:1) in 2 fetuses, 10 cases were accompanied by another arrhythmias: 4x SVT, 4x sinus bradycardia, 2x premature ventricular contractions (PVC). There were 3 fetuses diagnosed with heart defects and 7 with extracardiac malformations. Fetal echocardiography revealed additional functional circulatory changes in 7 fetuses with premature atrial contractions. Myocarditis was recognized in 2 fetuses. The mode of delivery was analyzed in 128 cases. In the first group 27 patients (32%) underwent caesarean section, in the second group--23 (62%), in the third group 3 patients (43%), respectively. Cardiac indications for caesarean section equalled 22% of all the indications occurring in fetuses suffering from arrhythmia. CONCLUSIONS: Caesarean section is much more commonly performed among fetuses diagnosed with arrhythmia accompanied by another fetal anomalies comparing to the group of fetuses with isolated arrhythmia. Although there are no particular cardiac indications for such way of delivery, total amount of caesarean sections performed in that group is really great. Above all, it may suggest that the obstetrician is under pressure of stress while making decision concerning caesarean section performance, even when there are no other indications and the condition of fetus is stable enough.

[Analysis of cases with fetal extrasystole coexisting with cardiac and extracardiac pathology]. / Analiza plodów z arytmia nadkomorowa wspólistniejaca z nieprawidlowosciami w ukladzie krazenia plodu lub wadami pozasercowymi.

OBJECTIVE: The paper presents a review of cases with fetal extrasystole coexisting with different cardiac and extracardiac pathology. DESIGN: The aim of the study is to analyse the results of echocardiographic examinations of fetuses with premature atrial contractions (PAC) quantitatively significant (bigeminy, trigeminy) or coexisting with other abnormal findings in fetal heart or other extracardiac pathologies. MATERIAL AND METHOD: Selected group of 33 (24%) fetuses from 135 with fetal extrasystole was analyzed. The mean gestational time of diagnosis was 29.2 + 4.1 weeks. RESULTS: Quantitatively significant arrhythmia (bigeminy, trigeminy) was diagnosed in 14 fetuses. Blocked PAC (2:1) occurred in two cases causing fetal bradycardia. Premature atrial extrasystole coexisting with different type of arrhythmias were diagnosed in 10 cases (4 x with SVT, 4 x with sinus bradycardia, 2 x with ventricular extrasystole). Heart defects in the analyzed group with PAC were recognized in two fetuses (1 x d-TGA, 1 x heterotaxy syndrome--common a-v canal). Myocarditis was diagnosed in 3 (9%) cases. From the group of 33 fetuses 6 newborns died (1 x d-TGA, 1 x T18, 1 x myocarditis, 1 x circulatory centralization). Mortality in the analyzed group was 18.2%. CONCLUSION: In cases of fetal arrhythmias echocardiography should be widely applied in order to evaluate the kind of arrhythmia, sufficiency of circulation and coexistence of heart defects, extracardiac malformations or functional abnormalities with arrhythmia in fetal circulation.

Fetal bradycardia in the first trimester: an unusual presentation of atrial extrasystoles.

We report a fetus with fetal bradycardia at 13 weeks of gestation secondary to atrial extrasystoles. The fetus subsequently developed paroxysmal supraventricular tachycardia and hydrops fetalis. The cardiac arrhythmia recovered spontaneously without any medical intervention. This case illustrates that atrial ectopic beats can present in the first trimester with fetal bradycardia. Rapidly evolving hydrops fetalis secondary to supraventricular tachycardia can develop, warranting close monitoring with weekly heart rate assessment. Fetal bradycardia secondary to atrial extrasystole should be differentiated from first trimester sinus bradycardia and those associated with major structural cardiac abnormality, which have a high fetal loss rate.

Use of tissue velocity imaging in the diagnosis of fetal cardiac arrhythmias.

BACKGROUND: Precise diagnosis of cardiac arrhythmias in the fetus is crucial for a managed therapeutic approach. However, many technical, positional, and gestational age-related limitations may render conventional methods, such as M-mode and Doppler flow methodologies, or newer techniques, such as fetal electrocardiography or magnetocardiography, difficult to apply, or these techniques may be unsuitable for the diagnosis of fetal arrhythmias. METHODS AND RESULTS: In this prospective study, we describe a novel method based on raw scan-line tissue velocity data acquisition and analysis. The raw data are available from high-frame-rate 2D tissue velocity images and allow simultaneous sampling of right and left atrial and ventricular wall velocities to yield precise temporal analysis of atrial and ventricular events. Using this timing data, a ladder diagram-like "fetal kinetocardiogram" was developed to diagram and diagnose arrhythmias and to provide true intervals. This technique was feasible and fast, yielding diagnostic results in all 31 fetuses from 18 to 38 weeks of gestation. Analysis of various supraventricular and ventricular arrhythmias was readily obtained, including arrhythmias that conventional methods fail to diagnose. CONCLUSIONS: The fetal kinetocardiogram opens a new window to aid in the diagnosis and understanding of fetal arrhythmias, and it provides a tool for studying the action of antiarrhythmic drugs and their effects on electrophysiological conduction in the fetal heart.

[Supraventricular tachycardia and premature atrial contractions in fetus]. / Supraventriculaire tachycardieën en premature atriumcontracties bij de foetus.

Foetal arrhythmias are encountered in 1-2% of pregnancies and 10% of these are associated with some form of foetal mortality or morbidity, including structural heart disease, foetal death and neurological complications. The most frequent types of arrhythmia are supraventricular arrhythmias of which the innocent premature atrial depolarisations make up 85%; 10% are tachycardias with a foetal heart rate of over 180/min. Echocardiographic evaluation is required to exclude associated structural abnormalities and to decide whether therapy is required. The prognosis of a foetus with tachycardia depends on the presence of associated pathology, the type of arrhythmia, the presence of foetal hydrops, the heart rate and the adequacy of treatment. The treatment of foetal tachycardia depends on the type of the tachycardia and since most tachycardias are of supraventricular origin the therapeutic armamentarium includes digoxin, sotalol and flecainide, each with its specific side effects. Foetal tachycardia patients require immediate diagnosis and if necessary therapy in a specialized center.

Familial association of congenital left heart abnormalities and sustained fetal arrhythmia.

Hypoplastic left heart syndrome (HLHS) is the most common cause of death from heart disease in the first week of life. There are reports about familial concordance by presumed morphogenetic mechanisms of abnormal embryonic blood flow with phenotypes of varying severity. The risk of having a child with a left heart lesion after a previously affected child may be as high as 5% to 12%. We present case reports from four families in which sustained fetal arrhythmia (three ectopic atrial tachycardias and one severe bradycardia due to excessive ectopic atrial beats) was demonstrated. Within these four families a close relative of the mother (a previous child, a brother, or a nephew) had severe left heart abnormality (three with HLHS and one with severe aortic valve stenosis). The association of sustained fetal arrhythmia of ectopic atrial origin and severe left heart abnormalities could be expected to occur by chance in a very low percentage of cases. We conclude that sustained fetal atrial ectopic arrhythmia is a congenital abnormality and should be considered as a risk factor for inherited congenital heart abnormalities.

Parasympathetic activity in Friedrich's ataxia.

We compared 19 patients with Friedreich's ataxia, a progressive hereditary neuromuscular disorder, with 19 healthy age-matched subjects. During nighttime, patients had shorter mean RR and decreased heart rate variability parameters related to parasympathetic activity than healthy subjects, whereas no difference occurred during daytime.