Nonsustained Supraventricular Tachycardia Research Articles

Detection of Non-Sustained Supraventricular Tachycardia in Atrial Fibrillation Screening.

Non-sustained supraventricular tachycardia (nsSVT) is associated with a higher risk of developing atrial fibrillation (AF), and, therefore, detection of nsSVT can improve AF screening efficiency. However, the detection is challenged by the lower signal quality of ECGs recorded using handheld devices and the presence of ectopic beats which may mimic the rhythm characteristics of nsSVT. The present study introduces a new nsSVT detector for use in single-lead, 30-s ECGs, based on the assumption that beats in an nsSVT episode exhibits similar morphology, implying that episodes with beats of deviating morphology, either due to ectopic beats or noise/artifacts, are excluded. A support vector machine is used to classify successive 5-beat sequences in a sliding window with respect to similar morphology. Due to the lack of adequate training data, the classifier is trained using simulated ECGs with varying signal-to-noise ratio. In a subsequent step, a set of rhythm criteria is applied to similar beat sequences to ensure that episode duration and heart rate is acceptable. The performance of the proposed detector is evaluated using the StrokeStop II database, resulting in sensitivity, specificity, and positive predictive value of 84.6%, 99.4%, and 18.5%, respectively. The results show that a significant reduction in expert review burden (factor of 6) can be achieved using the proposed detector.Clinical and Translational Impact: The reduction in the expert review burden shows that nsSVT detection in AF screening can be made considerably more efficiently.

Diagnostic yield of ambulatory cardiac monitoring in pediatric patients with palpitations.

Palpitations are a frequent reason for referral to pediatric cardiology providers and diagnostic workup includes ambulatory cardiac monitoring. While common practice, the diagnostic yield is unknown in the pediatric population. The objective is to evaluate the diagnostic yield of 24-h Holter and extended ambulatory cardiac monitoring in pediatric patients with palpitations. All pediatric patients aged 10-18 years who had ambulatory cardiac monitoring (1-30 days) through the Pocket Electrocardiogram (PocketECG™) system (Medi-Lynx) between January 2016 and July 2020 were included. Patients with an International Classification of Diseases-10 diagnosis code of palpitations (R00.2) during enrollment were evaluated separately. Tachyarrhythmia diagnoses included atrial fibrillation (AF), nonsustained supraventricular tachycardia (nSVT), supraventricular tachycardia (SVT), nonsustained ventricular tachycardia (nVT), and ventricular tachycardia (VT). Age, heart rates, arrhythmia type, and symptomatic transmission data were collected and analyzed. A total of 2388 patients (mean age 11.6 years, 58% F) with the R00.2 code had ambulatory cardiac monitoring (28% 24-h Holter, 72% extended) performed during the study period and there were 6287 total patients (mean age 13.9 years, 54% F) that underwent ambulatory cardiac monitoring (42% 24-h Holter, 58% extended) during that time. Of 2388 patients, 321 (13%) were diagnosed with tachyarrhythmia: AF (9), nSVT (192), SVT (59), and nVT (61). In the overall cohort, 764 (12%) patients were diagnosed with tachyarrhythmia: AF (22), nSVT (478), SVT (85), nVT (177), and VT (2). Symptomatic transmissions with normal cardiac rhythm were common in the R00.2 (n = 1697, 71%) and overall (n = 3848, 61%) groups. No episodes of nSVT, SVT, nVT, or VT were associated with symptomatic transmissions. Ambulatory cardiac monitors are an integral part of the diagnostic workup for pediatric palpitations patients and have demonstrated a high yield of combined positive arrhythmia diagnoses and symptomatic normal transmissions. Further prospective study of this population with the integration of clinical information is warranted.

Heart rate fragmentation as a marker of altered global autonomic nervous system activity: a novel predictor of atrial fibrillation occurrence in the general population

Abstract Background The dysfunction of the autonomic nervous system (ANS) plays an important role in the initiation and maintenance of atrial fibrillation (AF). However, the meaning of high heart rate variability (HRV) in predicting AF is still under debate due to conflicting results in population-based studies. Short-term HRV is conceptually attributed to vagal tone modulation. But recent data suggest that a component of short-term HRV, called heart rate fragmentation, is related to ANS breakdown. On the other hand, parasympathetic activity could be assess by a novel metric, the deceleration capacity (DC). Objective To assess predictive capacity of novel HRV-derived metrics, whether fragmentation indices or parameters of vagal tone, regarding the occurrence of AF in general population during long-term follow-up. Methods A cohort study was designed to prospectively assess the predictive value of ANS activity level among a healthy retired French population, regarding cardiovascular events and mortality. 1011 subjects aged 65 were enrolled in the study from 2000 to 2002. The enrolled population had no history of AF and a low cardiovascular risk. A median follow-up of 17.8 years (16.0–18.5) was managed. HRV data were acquired by 24-h Holter electrocardiogram (ECG) monitoring at baseline and assessed by frequency domain and time domain methods. Heart rate fragmentation using the percentage of inflection points (PIP), and assessment of specific parasympathetic activity using DC were then calculated. The study outcome was the onset of AF during follow-up, defined as a standard 12-lead ECG or Holter recording with ≥30 s of AF. Results AF was diagnosed in 123 patients along the 18-year follow-up, representing a cumulative incidence of 13.4%. Using univariate analysis (Figure 1A), a higher percentage of NN intervals that differ by more than 50 ms from the previous interval (pnn50) and root mean square differences of successive NN intervals (RMSSD) were associated with AF onset (p<0.01). A lower ratio of low-frequency and high-frequency component (LF/HF) was the only frequency-domain parameter found to predict the AF occurrence (p<0.01). The occurrence of AF was predicted by a higher PIP (p<0.01) and lower DC (p<0.01). Through multivariate analysis using clinical parameters that reached statistical significance in univariate analysis (Figure 1B), higher PIP was found as an independent predictor of AF occurrence (HR=2.1, 95% CI: 1.1–3.9, p=0.02), as well as male gender (HR=2.1, 95% CI: 1.1–3.9, p=0.02), and non-sustained supraventricular tachycardia (HR=2.1, 95% CI: 1.1–3.9, p=0.02). Conclusion (see Figure 2) Elevated PIP, a marker of heart rate fragmentation secondary to impaired ANS activity, is an independent predictor of the onset of AF in the healthy general population. Therefore, high HRV associated to AF occurrence could be the consequence of general ANS impairment rather than increased parasympathetic activity. Funding Acknowledgement Type of funding sources: None.

The feasibility and safety of stepwise protocol in cardiopulmonary exercise testing-exercise stress echocardiography for subjects with heart failure.

Exercise stress testing using a ramp protocol has been favored for cardiopulmonary exercise testing (CPX) in patients with heart failure (HF). However, the stepwise protocol for CPX was preferred for its possible combination with exercise stress echocardiography (ESE). We, therefore, investigated the feasibility and safety of using a stepwise protocol for CPX-ESE in patients with HF. Ambulatory outpatients with chronic HF were enrolled for a symptom-limited stepwise bicycle exercise test in the semi-supine position on a cycle ergometer. The test was started at a workload of 30 W and increased by 15 W every 3 minutes until maximal exertion. The echocardiographic and respiratory variables and any complications during the exercise were recorded. Among a total of 36 participants (age 61.2 ± 12.4 years; 69.4% men), all subjects achieved anerobic threshold during CPX-ESE and reached 72.3% of the age-predicted peak heart rate. The peak oxygen consumption was 14.7 mL/kg/min, and the peak RER was 1.25. There were no severe adverse complications, and only two minor rhythmic events were reported: nonsustained supraventricular tachycardia and isolated ventricular premature beats. The echocardiographic images acquired at each stage were of good quality in 92.6% of all acquisitions, and the intra-observer and interobserver repeatability was >80%. The stepwise protocol, with an initial workload of 30 W, followed by 15 W increments every 3 minutes, was feasible and provided an adequate stress load for patients with HF. This exercise stress modality was safe and well-tolerated.

Ambulatory Cardiac Monitoring in Infants with Supraventricular Tachycardia.

Supraventricular tachycardia (SVT) is a frequent cause of tachyarrhythmia in infants < 1year of age and ambulatory cardiac monitoring is an important tool for diagnosis and follow-up of these patients. We retrospectively reviewed 594 infants (mean age 4.05months, SD 3.55; 54% M) who underwent ambulatory cardiac monitoring (69% 24h Holter, 31% extended monitor) through the Pocket ECG system (MediLynx) between January 2016 and July 2020. 170 patients who had the ICD-10 code I47.1 for SVT used at enrollment were analyzed separately. 49 (8.3%) patients had sustained SVT or non-sustained SVT (nSVT) during the study period, including 20 patients (11.8%) who had the ICD-10 code I47.1 at enrollment. Extended ambulatory cardiac monitors detected 61% of all patients with nSVT or SVT and was superior when compared to 24h Holter (p < 0.0001). In the overall group, the first episode of SVT or nSVT was detected within 24h of monitoring in 40/49 patients (82%). 48/49 patients (98%) were diagnosed within a week of monitoring and the single remaining patient was diagnosed with nSVT at day 15 of monitoring. There was no significant difference in minimal, maximal, and average heart rate between patients with and without ICD-10 code I47.1 at enrollment or between patients with and without SVT or nSVT. Despite their low yield, ambulatory cardiac monitors are an important diagnostic tool. The ideal length of monitoring in patients with known or suspected SVT has yet to be defined, although all patients in our cohort were identified by day 15 of monitoring.

0524: Experience with foetal supraventricular arrhythmias

This study was to review experience and outcomes of supraventricular (SV) arrhythmias in fetus Methods: Cases were divided in groups: SVPB= premature SV beats, NSSVT= non-sustained SV tachycardia, SSVT= sustained SV tachycardia, and AF= atrial flutter. Heart failure (HF) was defined as foetal hydrops or isolated effusion (pericardial or pleural or ascitis). Outcome was favourable if arrhythmia resolved or stabilized until full-term birth, not-favourable if premature birth or foetal death occurred. 188 fetuses were included:89 in SVPB(47.3%), 31 in NSSVT(16.5%), 60 in SSVT(31.9%), 8 in AF(4.3%), aged at diagnosis 30.8±4.5weeks (no difference between groups). Foetus HR at diagnosis was 241±30bpm in SSVT vs 226±26 in AF. Antiarrhytmic therapy was administered in sustained tachycardia (83% of SSVT and 71% AF): 28 had 1 medication, 25: 2 medications, 2: 3 medications. Complication occurred in 29 cases, all in SSVT and AF (29 of 68= 43%): 18 hydrops, 5 ascitis, 4 pericarditis, 1 pleural effusion and 1 LVdysfunction+MR, was more frequent in SSVT (86%: hydrops in 30%) than AF (51%: no hydrops), p= 0.08. Fetal HF was associated with HR at diagnosis: 251±25bpm in hydrops vs 228±31bpm in nohydrops (p=0.025). Outcome was favourable in SVPB and NSSVT, in 45 of SSVT+AF (79%). Tachycardia resolved in 36, more frequently in SSVT (57%) than AF (25%). HR only decreased in 9cases. Premature birth occurred in 10, foetal death in 2. Outcome was not associated with HR or weeks of gestation at diagnosis. Defavourable outcome was more frequent in hydrops or isolated effusion (57%) than in uncomplicated cases (10%, p= 0.0002). Resolution occurred in 45% hydrops vs 66% of non-hydrops cases. Digoxine decreased from 79% of cases before 2000 to 33% after 2000, while flecaine increased from 14% to 48.5%. There was no relationship between therapy or number of medications and outcomes. Fetal SSVT more frequently resolves but has worse outcome than AF, especially if HR at diagnosis is high and hydrops occurs. Larger scale prospective studies are needed to evaluate the efficacy of flecaine compared to digoxine therapy.

First Berlin Heart EXCOR Pediatric VAD Interhospital Transports of Nonambulatory Patients with the Ikus Stationary Driver

Ventricular assist devices (VADs) are increasingly being used in pediatric patients to support cardiac failure. As more centers adopt this technology, there may be a need to transport these patients over long distances to facilitate patient care and organ transplantation. Food and Drug Administration indications for use state only that the patient must be a candidate for transplantation and does not place restrictions on the transplant capabilities of the implanting medical center. Nontransplanting institutions are able to use this technology with a predetermined agreement to transfer the patient to a partnering transplant center. We report the first two cases of interhospital air and ground transport of nonambulatory or intubated pediatric (<13 kg) patients supported by Berlin Heart EXCOR pediatric VADs and Ikus stationary drivers. We present our protocol for transporting this delicate patient population. In addition, we discuss important challenges encountered on these operations regarding vehicle transfers and the management of vehicle power supply. These two cases demonstrate that the transportation of pediatric patients on Berlin Heart VADs is feasible and safe and should be considered a treatment option in certain situations.

Abstract 315: Feasibility of outpatient ambulatory ECG monitoring to screen for silent atrial fibrillation: Pilot Findings from Screening Trial for Undiagnosed Atrial Fibrillation (STUDY-AF)

INTRODUCTION: Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, accounting for up to one in five strokes. Identification of silent AF could reduce the total burden of stroke, particularly with newer, low-cost noninvasive methods of screening. We therefore performed a pilot study of ambulatory ECG monitoring to screen for AF. METHODS: We performed a prospective screening study by enrolling patients from May 2012 to January 2013 in outpatient clinics for cardiology, echocardiography, and stress testing at the VA Palo Alto Health Care System. Patient inclusion criteria were age ≥ 55 years and at least two of the following risk factors: coronary disease, congestive heart failure (CHF), hypertension, diabetes, and sleep apnea. We excluded patients with 1) a history of AF, supraventricular tachycardia, stroke, transient ischemic attack, systemic embolism, implantable pacemaker or defibrillator; 2) palpitations or syncope in the prior year. All patients received a small, wearable patch-based ambulatory ECG monitoring device (Zio® Patch, iRhythm Inc., San Francisco, CA) for up to two weeks of uninterrupted monitoring. The primary outcome was proportion of patients with AF. Secondary outcomes were prevalence of sustained and non-sustained ventricular tachycardia (NSVT) and supraventricular tachycardia (SVT). RESULTS: Among 57 patients (age 68 ± 7.4 years, 0% women), 53 (93%) completed ambulatory monitoring. The highest sites of enrollment were in cardiology clinic (47%) and echocardiography (46%). Atrial fibrillation was detected in three subjects (5.7%), who had a mean AF Burden of 4.2%. Common asymptomatic arrhythmias detected were SVT of ≥ 4 beats (N=37; 70%), ≥ 8 beats (N=24; 45%), and ≥ 60 seconds (N=4, 7.5%). Asymptomatic NSVT of ≥ 4 beats (N=16; 30%) and ≥ 8 beats (N=5, 9.4%) were also detected. CONCLUSION: Ambulatory screening of asymptomatic arrhythmias using the Zio® Patch is feasible; however the diagnostic yield for silent AF may be low, even among patients with established AF risk factors. Our study found a high prevalence of incidental asymptomatic SVT and NSVT. A larger trial with more targeted enrollment may be required to demonstrate the value of screening for AF. The impact of detecting incidental NSVT or SVT, which themselves could prompt evaluation and may be relevant to development of AF, requires further investigation.

Abstract TMP52: The Role of Non-sustained Short Lasting Runs of Supraventricular Tachycardia and Atrial Fibrillation as a Causative Factor in Ischemic Stroke

Background: The widespread use of ambulatory cardiac monitoring has not only increased the detection rate of chronic or paroxysmal atrial fibrillation (AF), but also made it possible to identify other aberrations such as short lasting (&lt;30 secs) irregular runs of non-sustained supraventricular tachycardia (NS-SVT). Despite their resemblance to AF, these rhythms cannot be classified as paroxysmal AF due to their non-sustained nature. Furthermore, it is currently unclear whether they play a similar role in stroke pathophysiology like their chronic and paroxysmal counterparts. In this study, we determined prevalence of NS-SVT/AF in various subtypes of ischemic stroke and compared imaging features associated with these arrhythmias to imaging findings in chronic AF. Methods: This was a retrospective analysis of ischemic stroke patients admitted to a tertiary care center over 2 years. SVTs lasting &lt;30 secs with an irregular RR interval on 24 hour holter were classified as NS-SVT/AF. MRI and angiographic features suggestive of embolism were determined in all patients. Statistical analyses were performed to compare clinical characteristics of patients with and without NS-SVT/AF. Imaging data was analyzed for prevalence of embolic patterns in patients with NS-SVT/AF and chronic AF. Results: The study population consisted of 370 patients. Patients with NS-SVT/AF (n=89) were older (p&lt;0.01), more likely to be female (p=0.03) and had more commonly a history of hypertension (p=0.02). The distribution of stroke subtypes and specifically the prevalence of cryptogenic strokes did not significantly differ among both groups (p=0.15 and p=0.53, respectively). Patients with cryptogenic stroke and NS-SVT/AF had less commonly chronic embolic lesions (p=0.03) and angiographic evidence of abrupt-cut off or recanalization (p=0.09) compared to patients with chronic AF. Conclusions: The clinical characteristics of patients with NS-SVT/AF differ from patients without these arrhythmias, yet prevalence of NS-SVT/AF is similar among various stroke subtypes. More importantly, imaging characteristics do not entirely resemble patterns observed in patients with chronic AF. Further studies are needed to clarify the role of NS-SVT/AF in ischemic stroke.

Pacemakers do not always tell the truth: diagnosis of ventricular tachycardia for supraventricular tachycardia on pacemaker telemetry

Pacemaker telemetry reflects algorithm-dependent interpretations about the cardiac rhythm. For these data to be useful, it is necessary to recognize the limitations of each algorithm and its interactions with pacing and sensing parameters. We report on a case in which pacemaker Holter recording showed several episodes of nonsustained supraventricular tachycardia which were erroneously classified as ventricular tachycardia.

Reduced Postoperative Atrial Fibrillation Using Multidrug Prophylaxis

Atrial fibrillation (AFIB) is the most common complication following coronary artery bypass grafting (CABG). Despite three decades of recognition, efforts to reduce the high incidence reported (15%-30%) have been largely unsuccessful. Reasons for postoperative AFIB are likely multifactorial. As a result, we defined a multidrug prophylaxis based on agents known to be individually effective. This method was applied prospectively to a series of consecutive CABG patients with the goal of reducing the incidence of new-onset postoperative AFIB. Isolated CABG with cardiopulmonary bypass was performed on 517 consecutive patients. A rapid recovery protocol emphasizing AFIB multidrug prophylaxis was applied to all patients. All patients received 10 microg of triiodothyronine intraoperatively when the clamp on the aorta was released. Immediately following CABG, parenteral magnesium was administered to assure a serum magnesium > 2.2 mEq/dL. Thyroxine 200 microg was administered parenterally to all patients on postoperative days 1 and 2. Metoprolol (25 mg to 100 mg/day) was begun on all patients after extubation provided: heart rate > 85 beats/min and systolic blood pressure > 130 mmHg. Parenteral procainamide (12 mg/kg) loading dose, followed by a maintenance dose (2 mg/min), was used for patients who developed premature atrial contractions (> 1/min), nonsustained supraventricular tachycardia, or any episodes of atrial fibrillation. All patients also received postoperative digitalization, steroids, and aggressive diuresis. The 30-day operative mortality was 3.7%. The overall incidence of new-onset postoperative AFIB was 10.3% (53 patients). There was no major difference in operative mortality (7.5% vs 3.2%, p = 0.23), Parsonnet risk score, or intraoperative variables between AFIB patients and the non-AFIB patients. Patients presenting with a preoperative acute myocardial infarction (p < 0.05), left main stenosis > or = 70% (p < 0.01), and advanced age > or = 70 years (p < 0.05) were at increased risk of developing AFIB. The length of stay for patients with AFIB was 9.9 +/- 9.6 days versus 5.9 +/- 5.2 days (p < 0.001). Application of a multidrug prophylaxis can reduce postoperative AFIB to a low incidence. Identification of associated clinical features can help predict patients at risk for postoperative AFIB. Additional strategies to target postoperative AFIB may include treatment at the earliest recognition of atrial rhythm instability.

Cardiac Arrhythmias Triggered by Sudden and Dynamic Efforts

Some arrhythmias are triggered only during exercise. The aim of this study is to describe the frequency and type of arrhythmia induced by a standardized protocol of sudden and dynamic exercise, which tends to reflect routine situations of efforts (e.g., climbing stairs), and compare with those found on maximal cardiopulmonary exercise test (CPET). A total of 2329 subjects (1594 men) aged 9-91 years (mean 52 years, SD +/- 16) were submitted to a standardized protocol of sudden and dynamic exercise (4-second exercise test [4sET]) prior to a CPET. A continuous digital electrocardiogram (ECG) was recorded during 4sET and CPET, and later reviewed and interpreted by the same physician (who supervised all the procedures). A total of 1125 subjects (43%) had cardiac arrhythmias during one or both procedures. About 57% of the arrhythmias were supraventricular, but 47 subjects (2% of all subjects) presented more complex arrhythmias including 43 cases of nonsustained supraventricular tachycardia and four nonsustained ventricular tachycardia. While arrhythmias were more often exposed by the CPET (P < 0.01), in 221 cases (10% of the total sample) of arrhythmias they were only induced by 4sET; these included four cases of nonsustained supraventricular tachycardia. 4sET-induced arrhythmias tend to be simple and were always short-lasting. In some cases, ECG recording during 4sET showed arrhythmias that would not be induced by a progressive maximal exercise test. Different situations of exercise, sudden and short versus maximal and progressive, tend to generate different arrhythmic responses and possibly complementary clinical implications.

Comparison of heart rate variability and cardiac arrhythmias in polluted and clean air episodes in healthy individuals

Pathophysiological mechanisms and pathways linking cardiovascular mortality and morbidity with air pollution were recently hypothesized. The present study evaluated association between air pollution and changes in heart rate variability as a marker of cardiac autonomic function in healthy individuals, and also determined the frequency of cardiac arrhythmias and QT interval changes on polluted compared to unpolluted days. Continuous Holter electrocardiography (ECG) monitoring was conducted on 21 young healthy individuals in the two episodes of clean air and elevated air pollution in Tehran. All subjects underwent a medical history review, a physical examination and echocardiography in order to rule out structural heart diseases. Measured pollutants and parameters included NO(2), CO(2), O(3), SO(2), and PM10, which all showed significantly higher concentrations on polluted days. Holter parameters were measured for 24-h time segments and compared. Maximum heart rate was significantly lower in polluted air conditions in comparison with clean air conditions (115.1±32.2 vs. 128.9±17.7), and the square root of the mean of squared differences between adjacent NN intervals (r-MSSD) was higher in polluted air compared to clean air (99.0±58.2 vs. 58.5±26.4). Also, the occurrence of nonsustained supraventricular tachycardia was reported in 42.9% of participants in air pollution episodes, whereas this arrhythmia was not seen in clear air conditions (p=0.001). Changes in air pollution indices may lead to the occurrence of nonsustained supraventricular tachycardia, a slight reduction in maximum heart rate, and an increase in r-MSSD in healthy individuals. Air quality monitoring in cities associated with a high exposure to air pollutants is recommended in order to prevent such events.

How often does spirometry testing induce cardiac arrhythmias?

To describe the frequency and type of arrhythmia induced by forced expiratory and inspiratory flow-volume loop manoeuvres. 735 subjects (548 men) aged from 10 to 98 years old (mean 54 years, SD +/- 15) were submitted to a conventional medical examination and spirometry testing prior to a maximal cardiopulmonary exercise test (CPET). A continuous digital electrocardiogram (ECG) was recorded during spirometry and CPET, and later reviewed and interpreted by the same physician (who supervised all the procedures). 470 subjects (64%) had cardiac arrhythmias during one or both procedures. About 60% of the arrhythmias were supraventricular, but 35 subjects (5%) presented more complex arrhythmias including frequent premature ventricular beats (n=31) or non-sustained ventricular tachycardia (n=4). While arrhythmias were more often exposed by the CPET (p<0.01), in 68 cases (10% of the total sample) arrhythmias were only induced by spirometry; these included four cases of non-sustained supraventricular tachycardia (n=4). Spirometry is a safe procedure with regard to induction of cardiac arrhythmias. Spirometry-induced arrhythmias tend to be simple and were always short-lasting. In some cases, ECG recording during spirometry showed arrhythmias that would not be induced by a progressive maximal exercise test.

Predictors of Syncope in Patients with Hypertrophic Cardiomyopathy

Approximately 30% of patients with hypertrophic cardiomyopathy (HCM) suffer syncope and syncope was the only symptom associated with sudden death. However, no systematic studies in large cohorts looking at predictors of syncope are available in the literature. Therefore, we sought to determine predictors of syncope in patients with HCM. One hundred and seventy-three consecutive patients with HCM and a mean age of 42 +/- 18 years (range 10-78) underwent extensive clinical, electrocardiographic, and echocardiographic testing to identify predictors of syncope. During the mean follow-up duration of 50 months, syncope occurred in 28% of the HCM patients. Univariate analysis showed male gender, age <40 years, family history of sudden death, PR interval, QRS width, >or=2 bursts of nonsustained ventricular tachycardia (NSVT), >or=3 bursts of nonsustained supraventricular tachycardia (NSSVT), maximum left ventricular wall thickness >or=30 mm, and abnormal blood pressure response, out of 24 demographic, clinical, hemodynamic, electrocardiographic, and echocardiographic features, to be significantly associated with syncope. Of these nine variables, the only independent predictors of syncope at multivariate analysis were age <40 years (odds ratio [OR]: 4.4, 95% confidence interval [CI]: 2.2-16, P = 0.003), >or=2 bursts of NSVT (OR: 9.9, 95% CI: 2.0-46, P = 0.0001), and >or=3 bursts of NSSVT (OR: 2.7, 95% CI: 0.38-8.25, P = 0.001). The concomitant occurrence of all three variables had a sensitivity of 87% and specificity of 73% in identifying the patients with syncopal events. The results of this study showed that age <40 years, bursts of NSVT, and NSSVT were independently associated with the risk of syncope in patients with HCM. Demographic data and ambulatory ECG findings could help in risk stratification of patients with HCM.

Long-term noninvasive arrhythmia assessment after total anomalous pulmonary venous connection repair

Pediatric patients with a history of atrial surgery are at risk for the development of sinus node dysfunction and atrial arrhythmias. However, there has been no comprehensive, long-term, electrophysiologic study of patients who have undergone repair of total anomalous pulmonary venous connection. We evaluated school-aged and adolescent survivors of isolated total anomalous pulmonary venous connection repair from January 1983 to December 1996 to assess for sinus node dysfunction, atrioventricular block, and atrial and ventricular arrhythmias. Assessment was limited to an electrocardiogram, 24-hour Holter monitor, and exercise stress test. Twenty-nine children were evaluated 11.2 +/- 3.6 years after their initial operative repair. The mean age at repair was 36.0 +/- 43.0 days. Electrophysiologic studies revealed evidence of sinus node dysfunction, including sinus bradycardia, sinus pauses, and chronotropic impairment, in most of the patients. Twenty-nine percent of patients showed chronotropic impairment on exercise testing. Atrioventricular conduction abnormalities occurred in 2 patients. Single atrial and ventricular premature complexes were frequent, but complex tachyarrhythmias were less common. There was 1 patient who had nonsustained supraventricular tachycardia and 2 patients who had nonsustained ventricular tachycardia. No statistically significant relationships were found between hypothesized variables and arrhythmia outcomes. Survivors of total anomalous pulmonary venous connection repair appear to have a high incidence of signs of sinus node dysfunction and a low incidence of atrioventricular block in follow-up. Significant atrial and ventricular arrhythmias appear to be uncommon. Despite a favorable overall long-term outcome, these patients warrant ongoing clinical follow-up for arrhythmia surveillance.

190 Arrhythmic disorders and physiologic response during dobutamine stress echocardiography after acute myocardial infarction - influence of diabetes on

1 1 Medical University, II Chair of Cardiology, Lodz, Poland Aim: The purpose of the study was to evaluate long-term prognostic value of pharmacological stress echocardiography (SE) in patients with and with- out hypercholesterolemia (HCH). Methods: We followed 224 patients (62% men, age 55±10 yrs) who had undergone SE as the diagnostic test for ischemic heart disease. Myocardial infarction, need for revascularization or death were defined as endpoints (MACE) during the follow-up period of 53 months (range 12 to 91). The prog- nostic value of the test in patients with (50%) and without HCH was compared. Results: The prevalence of risk factors were: 44% for hypertension, 50% - hypercholesterolemia, 62% - history of smoking, 31% - previous myocardial infarction, 12% - diabetes. SE was positive for ischemia in 108 patients (48%). During then follow-up period 21 patients died (9%) and 102 (45%) experi- enced MACE. HCH and positive SE were independent predictors of events (Cochran-Cox: p=0.001, p<0.0001 respectively). However, positive result of SE in patients without HCH had higher prognostic value for MACE as com- pared with subset with HCH (HR: 3.57, p=0.0001 and HR: 2.05, p=0.003 respectively). Conclusion: In unselected patients undergoing diagnostic SE the presence of hypercholesterolemia limits the predictive value of positive SE for MACE. Patients and methods: The investigation comprised 128 patients, 55 diabet- ics (D) and 73 non-diabetics (ND) all with non-complicated AMI. 90 patients (70.3%) received thrombolityc therapy. After 10-12 days all of them underwent DSE testing and during the next 3-6 months coronary angiography. Results: Non-sustained ventricular and supraventricular tachycardia occurred in 7 D (12.7%) and 9 ND (12.3%) and in 6 D (10.9%) and 12 ND (16.4%). In 5 ND (6.8%) junction rhythm was developed, and in 4 D (7.2%) and 3 ND (4.1%) AV block II-III. Systolic blood pressure decrease of ≥ 40 mm Hg oc- curred in 6 D (10.9%) and 10 ND (13.7%). Significant coronary stenoses were found in 45 (81.8%) D and 42 (57.5%) ND. Diabetics vs non-diabetics had a higher baseline heart rate (83±11 vs 69±11 beats/min, p<0.001), with a higher age-predicted maximum heart rate at peak. In non-diabetics group there was no significant difference between patients with and without arrhythmias, regarding the mean number of diseased coronary arteries (1.61±0.7 vs 1.58±0.6). In diabetic group, patients with arrhythmias had greatest number of diseased coronary arteries (2.7±0.7 vs 1.52±0.4) Inde- pendent predictors of arrhythmias were: higher resting WMSI (p<0.01), and diabetes (p<0.1). Independent predictors of systolic blood pressure decrease of l 40 mm Hg were: higher baseline systolic pressure (p<0.0001); hyper- trophic left ventricle with diastolic dysfunction; and higher resting WMSI with systolic dysfunction. Conclusion: Physiological responses to dobutamine stress are comparable in diabetics and non-diabetics, except that a more rapid heart rate response is found in diabetics. Arrhythmic disorders during DSE in diabetic patients are predicted not only by the extent of systolic or diastolic left ventricular dysfunction, but also by the presence or the extent of CAD.

Arrhythmias after pediatric lung transplantation.

Atrial arrhythmias have been reported after congenital heart surgery involving extensive atrial suture lines. Experimental studies involving bilateral lung transplantation (Tx) suggest that the left atrial suture lines predispose to atrial flutter. The overall incidence and type of arrhythmias after pediatric lung Tx have not previously been described and therefore the purpose of this study was to prospectively screen and describe arrhythmias in a subset of our lung transplant population. Over a 1-yr study period, all recipients of bilateral lung Tx were admitted to a full-disclosure telemetry unit. Single-lead electrocardiograms were recorded continuously and reviewed daily via a beat-by-beat analysis. A total of 314 patient days (range 9-93, median 43 days) were recorded from seven patients. The incidence of arrhythmias observed per total patient days included junctional escape rhythm (4.8%), non-sustained ventricular tachycardia (4.1%), accelerated junctional (2.5%), sinus bradycardia (2.2%), non-sustained supraventricular tachycardia (1.3%), ectopic atrial tachycardia (1.0%), sustained ventricular tachycardia (0.3%), junctional ectopic tachycardia (0.3%), and second degree heart block (0.3%). No patient had sustained supraventricular tachycardia, atrial flutter, atrial fibrillation, or complete heart block. Arrhythmias were treated in two patients. During the follow-up period, one patient received amiodarone for ventricular tachycardia (which was also noted and treated prior to transplant). We conclude that among pediatric lung transplant recipients admitted for their transplant surgery, arrhythmia is uncommon and rarely requires therapy.

P-P Cycle Alternans During Atrial Tachycardia:.

Background: A-63 year-old man complaining of palpitations underwent a 24-hour ambulatory ECG monitoring that revealed the presence of recurrent episodes of nonsustained supraventricular tachycardia. Analysis of the tracings suggests an atrial origin of the arrhythmia. Tachycardias, quite regular at the beginning, suddenly showed a P-P cycle alternans, namely, P-P intervals alternately short and long. The evidence of two separate cycle ranges can be explained by the presence of a longitudinal dissociation within a discrete zone of the atrial circuit.

Fat necrosis after ice application for supraventricular tachycardia termination

Hypoglycemia was diagnosed in a term infant soon after birth. At 3 days of age he was noted to have episodes of sustained and nonsustained supraventricular tachycardia (SVT). He was transferred to our neonatal intensive care unit for evaluation and treatment. Oral amiodarone therapy was initiated at 4 days of age. During oral amiodarone loading he continued to have episodes of sustained and nonsustained tachycardia. Sustained episodes usually terminated with the use of ice to the face (the diving reflex).