Prevalence and Clinical Significance of Left Atrial Remodeling in Competitive Athletes

OBJECTIVES

In the present study we assessed the distribution and clinical significance of left atrial (LA) size in the context of athlete's heart and the differential diagnosis from structural heart disease, as well as the proclivity to supraventricular arrhythmias.

BACKGROUND

The prevalence, clinical significance, and long-term arrhythmic consequences of LA enlargement in competitive athletes are unresolved.

METHODS

We assessed LA dimension and the prevalence of supraventricular tachyarrhythmias in 1,777 competitive athletes (71% of whom were males), free of structural cardiovascular disease, that were participating in 38 different sports.

RESULTS

The LA dimension was 23 to 50 mm (mean, 37 +/- 4 mm) in men and 20 to 46 mm (mean, 32 +/- 4 mm) in women and was enlarged (i.e., transverse dimension > or = 40 mm) in 347 athletes (20%), including 38 (2%) with marked dilation (> or = 45 mm). Of the 1,777 athletes, only 14 (0.8%) had documented, symptomatic episodes of either paroxysmal atrial fibrillation (n = 5; 0.3%) or supraventricular tachycardia (n = 9; 0.5%), which together occurred in a similar proportion in athletes with (0.9%) or without (0.8%; p = NS) LA enlargement. Multivariate regression analysis showed LA enlargement in athletes was largely explained by left ventricular cavity enlargement (R2 = 0.53) and participation in dynamic sports (such as cycling, rowing/canoeing) but minimally by body size.

CONCLUSIONS

In a large population of highly trained athletes, enlarged LA dimension > or = 40 mm was relatively common (20%), with the upper limits of 45 mm in women and 50 mm in men distinguishing physiologic cardiac remodeling ("athlete's heart") from pathologic cardiac conditions. Atrial fibrillation and other supraventricular tachyarrhythmias proved to be uncommon (prevalence < 1%) and similar to that in the general population, despite the frequency of LA enlargement. Left atrial remodeling in competitive athletes may be regarded as a physiologic adaptation to exercise conditioning, largely without adverse clinical consequences.

Pharmacologic prophylaxis for postoperative atrial tachyarrhythmia in general thoracic surgery: Evidence from randomized clinical trials

BACKGROUND

Atrial tachyarrhythmia is the most common complication after general thoracic surgery and is associated with significant morbidity, longer hospital stay, and higher costs. We sought to determine whether the use of antiarrhythmic medications is associated with a reduced rate of postoperative atrial tachyarrhythmia.

METHODS

MEDLINE, EMBASE, Cochrane Database of clinical trials (1980-2003), and reference lists of relevant articles were searched for randomized controlled trials with placebo control, general thoracic patients, and noncombined and prophylactic use of the medications. Search, data abstraction, and analyses were performed and confirmed by at least 2 authors. A fixed-effects model was used to perform meta-analyses.

RESULTS

There were 11 unique trials (total n = 1294) that met the inclusion criteria. Calcium-channel blockers and beta-blockers reduced the risk of atrial tachyarrhythmia in 4 and 2 trials, respectively (relative risk of 0.50 and 95% confidence interval of 0.34-0.73; relative risk of 0.40 and 95% confidence interval of 0.17-0.95, respectively). However, beta-blockers tended to increase the risk of pulmonary edema (relative risk, 2.15; 95% confidence interval, 0.74-6.23). Magnesium tested in one unblinded trial also reduced the risk of atrial tachyarrhythmia (relative risk, 0.4; 95% confidence interval, 0.21-0.78). On the other hand, digitalis preparations were found to be harmful because they increased the risk of atrial tachyarrhythmia in 3 trials (relative risk, 1.51; 95% confidence interval, 1.00-2.28). Finally, 2 other medications, flecainide and amiodarone, were each tested in a single small trial, and their effects were associated with great uncertainty.

CONCLUSIONS

Calcium-channel blockers and beta-blockers are effective in reducing postoperative atrial tachyarrhythmia. The use of these medications should be individualized, and possible adverse events of beta-blockers should be taken into account. Randomized clinical trials do not support the use of digitalis in general thoracic surgery. The value of magnesium as a supplement to a main prophylactic regimen should be explored.

Atrial tachyarrhythmias after the maze procedure: incidence and prognosis

BACKGROUND

The Maze procedure restores normal sinus rhythm in the majority of patients. However, atrial tachyarrhythmias (ATA) are a common early complication after the operation. The purpose of this study was to define the incidence and natural history of ATA after the Maze procedure.

METHODS

Complete medical records from 200 patients who underwent the Maze procedures (I, II, and III) from 1987 to 2002 were examined for all episodes of early postoperative ATA that occurred during the first 30 days after the procedure. Two electrophysiologists independently reviewed all postoperative 12-lead electrocardiograms.

RESULTS

ATA occurred in 86 patients (43%) after the Maze procedure. Of the patients with ATA, 59% had atrial fibrillation (AF), 14% had atrial flutter (AFL), and 27% had both AF and AFL. Of the patients with AF or AFL, 20% and 5%, respectively, also had episodes of atrial tachycardia and supraventricular tachyarrhythmia. The peak incidence of early postoperative ATA was on postoperative day 8. The average duration of ATA was 5.7+/-5.0 days. Late recurrence of AF (>1 year postoperatively) occurred in 7.0% of patients who had early postoperative ATA and 8.8% of patients without early postoperative ATA (P=0.8).

CONCLUSIONS

ATA occurred in 43% of patients after the Maze procedure. The tachyarrhythmias occurred primarily within 8 days after surgery and resolved within 3 weeks in almost all patients. There was no relationship between the incidence of early postoperative ATA and the late recurrence of AF.

Spectrum and prognostic significance of arrhythmias on ambulatory Holter electrocardiogram in hypertrophic cardiomyopathy

OBJECTIVES

The goal of this study was to assemble a profile and assess the significance of arrhythmias in a nontertiary-based hypertrophic cardiomyopathy (HCM) cohort.

BACKGROUND

Hypertrophic cardiomyopathy is associated with arrhythmia-related consequences, particularly sudden death. Ventricular tachyarrhythmias on Holter electrocardiograms (ECG) have been reported as markers for sudden death in highly selected HCM populations.

METHODS

We assessed the profile of ventricular and supraventricular ectopy and bradyarrhythmia on ambulatory 24-h Holter ECG and also related these findings to clinical outcome in 178 HCM patients.

RESULTS

Of the 178 study patients, 157 (88%) had premature ventricular complexes (PVCs), including 21 (12%) with >/=500 PVCs, 74 (42%) had couplets, 67 (37%) had supraventricular tachycardia (SVT), and 56 (31%) had nonsustained ventricular tachycardia (NSVT). Mean number of PVCs was 330 +/- 763 (range 1 to 5,435) and increased with age (p < 0.01); NSVT was associated with greater left ventricular hypertrophy (p = 0.01) and severe symptoms (New York Heart Association functional classes III and IV) (p = 0.04); SVT occurred more commonly in patients with outflow obstruction (p = 0.02). Over a follow-up of 5.5 +/- 3.4 years, 11 (6%) patients died suddenly (annual mortality rate, 1.1%) including 5 patients with NSVT. For sudden death, NSVT on Holter ECG had negative and positive predictive values of 95% and 9%, and sensitivity and specificity of 45% and 69%, respectively.

CONCLUSIONS

In this nontertiary-based HCM cohort, ventricular and supraventricular tachyarrhythmias were particularly frequent and demonstrated a broad spectrum on ambulatory (Holter) ECG. Paradoxically, despite such a highly arrhythmogenic substrate, sudden death events proved to be relatively uncommon. Ventricular tachyarrhythmias had a low positive and relatively high negative predictive value for sudden death in this HCM population.

Midterm Results of Pulmonary Vein Isolation for the Elimination of Chronic Atrial Fibrillation

BACKGROUND

This study aims to clarify midterm results of chronic atrial fibrillation elimination after pulmonary vein isolation and provides an evaluation of factors influencing results.

METHODS

Forty-nine patients were enrolled in this study. We performed a simple pulmonary vein isolation with the aid of cryoablation or radiofrequency ablation directed towards the left posterior remnant of the posterior left atrium. Results were evaluated using elimination rates of atrial fibrillation during the postoperative follow-up for > 12 months. We also examined factors influencing the recurrence of atrial fibrillation.

RESULTS

There were no hospital deaths or serious complications among the 49 patients. The total follow-up duration was 137.2 patient years. Forty-seven patients (96%) were followed with serial consultations, but 2 patients were dropped from this study because of changes in residence. Thirty-five of 49 patients (71.4%) showed regular sinus or nodal rhythms at discharge. In 4 patients atrial fibrillation recurred during the follow-up period, whereas in another 4 patients sinus rhythm was restored, although they showed atrial fibrillation at discharge. The cumulative elimination rate was 70.2% (33 of 47 patients), which was determined at the last follow-up period. Large left atrial diameters, a long history of atrial fibrillation, and low-voltage fibrillatory waves in V1 leads were preoperative indicators of recurrence of atrial fibrillation.

CONCLUSIONS

Pulmonary vein isolations were effective in the treatment of chronic atrial fibrillation patients and sinus rhythms were restored within the follow-up period.

Supraventricular arrhythmias: an electrophysiology primer

Supraventricular arrhythmias are the most wide-spread group of arrhythmias and affect all age groups. Atrial fibrillation is the most common arrhythmic disorder and is even more prevalent among the elderly. Due to their prevalence, it is imperative for the clinician to be informed about these arrhythmias and treatment considerations. This paper presents a basic review of the incidence, pathophysiology, diagnosis, and treatment of supraventricular arrhythmias, along with gender differences, and discusses important implications for the health care provider. A summary of common electrocardiogram findings in supraventricular arrhythmias is presented along with a brief overview of pharmacologic agents.

Is amiodarone a safe antiarrhythmic to use in supraventricular tachyarrhythmias after lung cancer surgery?

BACKGROUND

Supraventricular arrhythmias after thoracotomy for pulmonary resections are well documented. There has been considerable interest in their incidence, nature, predictability from preoperative assessment and treatment. The purpose of this study is to define prevalence, type, risk factors for post-thoracotomy supraventricular arrhythmias and to assess the efficacy of amiodarone as an antiarrhythmic drug.

METHODS

The records of 250 patients undergoing pulmonary resection for lung cancer during last two years were followed up in this prospective study with particular attention to possible risk factors (gender, age, extent and side of resection, diabetes mellitus, hypertension, tobacco smoking, beta-blocker ingestion). Patients underwent biopsy only were excluded. Once onset of supraventricular arrhythmia was monitored or documented in the electrocardiogram, intravenous infusion of amiodarone was started with a loading dose of 5 mg/kg in 30 minutes and a maintenance dose of 15 mg/kg until remission of it.

RESULTS

Forty-three episodes (21.6%) of supraventricular arrhythmias were documented with atrial fibrillation being the most common (88.3%). Rhythm disturbances were most likely to develop on the second postoperative day. Pneumonectomy, lobectomy and age >65 years were the statistically significant factors. The overall postoperative mortality was 3.2% and 2.3% for the patients with postoperative supraventricular arrhythmias. In none of the cases did supraventricular arrhythmia cause cardiac failure leading to death. Sinus rhythm was achieved with amiodarone in 37 out of 43 patients (86%). Electrical cardioversion was necessary for 6 patients who were hemodynamically unstable. The most common amiodarone-related complication was bradycardia (13.5%).

CONCLUSIONS

Postoperative supraventricular arrhythmias are a common complication in elderly patients undergoing lung resection surgery (especially pneumonectomy or lobectomy). Amiodarone is both safe and effective in establishing sinus rhythm.

The prognostic significance of exercise-induced atrial arrhythmias

OBJECTIVES

The purpose of the study was to determine if atrial ectopy (AE) or atrial arrhythmias during exercise are predictive of an increased risk of cardiac events and death.

BACKGROUND

Although stress-induced atrial arrhythmias are common during exercise testing, there is a paucity of data regarding the correlation with underlying heart disease and cardiovascular outcomes. Atrial arrhythmias may reflect underlying left atrial enlargement and diastolic dysfunction, which are prognostic of mortality. We hypothesized that these stress-induced arrhythmias are associated with long-term adverse cardiac events.

METHODS

Exercise echocardiography was performed in 5,375 patients (age 61 +/- 12 years) with known or suspected coronary artery disease. An abnormal result was defined as exercise-induced atrial fibrillation (AF)/atrial flutter, supraventricular tachycardia (SVT), or AE.

RESULTS

A total of 311 (5.8%) patients died (132 [2.5%] from cardiac causes) over a period of 3.1 +/- 1.7 years. In addition, 193 (3.6%) patients experienced a myocardial infarction (MI) and 531 (9.9%) patients required revascularization. During exercise testing, 1,272 (24%) patients developed AE, 185 (3.4%) developed SVT, and 43 (0.8%) developed AF. The five-year cardiac death rate was not statistically different between groups (none [3.8%], AE [4.3%], SVT [3.7%], AF [0%], p = 0.43). The five-year rate of MI was significantly different between groups (none [5.7%], AE [8.3%], SVT [0%], AF [9.0%], p = 0.005). The five-year rate of revascularization between groups was not significantly different (none [14.2%], AE [17.0%], SVT [11.8%], AF [14.8%], p = 0.50). A composite of all five-year adverse end points was similar between groups (none [22.7%], AE [27.8%], SVT [17.7%], AF [25.7%], p = 0.10). In stepwise multivariate analysis, AE was not predictive of myocardial infarction when taking into account traditional clinical variables and exercise test results.

CONCLUSIONS

In this large cohort of patients, the occurrence of AE was predictive of an increased risk of MI. However, the association did not persist after adjustment for clinical and exercise variables known to predict adverse long-term cardiovascular outcomes. The rate of long-term cardiac death or revascularization was not influenced by the development of stress-induced atrial arrhythmias.

Catheter ablation of supraventricular tachycardia in the transplanted heart: a case series and literature review

Clinically important supraventricular arrhythmias are occasionally encountered in patients following cardiac transplantation and the use of catheter ablation as a treatment has been reported. The following three cases are described: (1) atrial flutter, including electroanatomic mapping of the donor and recipient components of the right atrium, (2) a mid-septal accessory pathway, and (3) atrioventricular nodal reentrant tachycardia (AVNRT). A Medline database search was performed and articles addressing catheter ablation following cardiac transplantation were reviewed. The efficacy of RFA for treating various arrhythmia mechanisms was evaluated based on a summary of published case reports.

Isolated noncompaction cardiomyopathy presenting with paroxysmal supraventricular tachycardia--case report and literature review

Isolated noncompaction cardiomyopathy is an exceedingly rare congenital cardiomyopathy. A case of isolated noncompaction cardiomyopathy is reported and the literature on the subject collected through a comprehensive literature search is reviewed. Fewer than 100 cases of this condition have been reported. Isolated noncompaction cardiomyopathy is caused by a defect in cardiac morphogenesis resulting in an arrest of compaction of loose interwoven meshwork of myocardial fibers during intrauterine life, which results in severe systolic dysfunction as well as undue hypertrophy of the involved walls of the ventricles. Although the most frequent sites involved are left ventricular apex and inferior wall, involvement of other left ventricular walls and right ventricle has also been reported. Etiology of the isolated noncompaction of myocardium is not clear. Familial cases have been reported and the mode of inheritance is heterogeneous. In X-linked form of the disease, a locus has been found on Xq28, and mutations have been reported in G4.5 gene. The age of onset of symptoms ranges from infancy to the geriatric age. Patients with isolated noncompaction cardiomyopathy have a high incidence of heart failure, arrhythmias, and thromboembolism. The most common presentation is congestive heart failure. Arrhythmias include atrial arrhythmias, ventricular tachycardia, and sudden cardiac death. The patient reported in this article presented with paroxysmal supraventricular tachycardia. Echocardiography is the procedure of choice to establish diagnosis. Due to the lack of associated cardiac anomalies, antenatal detection is difficult. The treatment is that for congestive heart failure, arrhythmias, and thromboembolism. The end-stage congestive heart failure is managed with heart transplantation and potential life-threatening ventricular tachyarrhythmias with an implantable cardioverter defibrillator. Prognosis is poor and the common causes of death are intractable heart failure and sudden cardiac death.

Common supraventricular arrhythmias in Indian population and their management

Supraventricular tachycardias (SVTs) present as recurrent palpitations. Unlike ventricular tachycardias, these arrhythmias usually carry a benign prognosis. It is important to exclude structural heart disease in these patients. Though vagal manoeuvres and drug therapy are useful for acute termination of SVTs, recurrences are common. Catheter ablation is safe, highly effective and has a curative potential. It obviates the need for long-term medical therapy as it eliminates the arrhythmia in these patients.

Arrhythmias in patients with congenital heart disease

Improved surgical outcome for patients with congenital heart disease (CHD) has created a rapidly expanding population of adolescents and young adult survivors. Cardiac arrhythmias are a common late sequelae of this form of heart disease. Effective treatment requires clear understanding of the underlying anatomic defect as well as the specific surgical interventions. Intraatrial reentrant tachycardia (IART) is the most common and difficult arrhythmia encountered in these patients. Traditional IART treatment with medication has been largely unsuccessful, but radiofrequency ablation has emerged in recent years as a promising option for many patients. The availability of three-dimensional mapping systems and irrigated-tip ablation catheters has improved acute success rates for IART to better than 90%. Postablation recurrence of IART still remains problematic for patients who have undergone the Fontan operation, in which case atrial maze surgery may be considered. Ventricular tachycardia (VT) is seen in a smaller number of CHD patients, most notably those with tetralogy of Fallot or aortic stenosis. The adoption of implantable defibrillator (ICD) therapy for these patients has improved outcome. Owing to their complex anatomy, the CHD population presents unique challenges during both catheterization and device implant. Multicenter study of this unique patient group is needed in order to develop more objective treatment guidelines.

Posterior pericardiotomy reduces the incidence of supra-ventricular arrhythmias and pericardial effusion after coronary artery bypass grafting

OBJECTIVE

The aim of this prospective study was to demonstrate the effectiveness of posterior pericardiotomy in reducing the incidence pericardial effusions and consequently reducing the related supraventricular tachyarrhythmias and development of delayed posterior cardiac effusions.

METHODS

This prospective randomized study was carried out in 150 patients undergoing coronary artery bypass grafting in Bayindir Hospital Department of Cardiovascular Surgery between April 2000 and October 2001. One hundred and fifty patients were divided into two groups; each group included 75 patients. A 4-cm longitudinal incision was made parallel and posterior to the left phrenic nerve, extending from the left inferior pulmonary vein to the diaphragm in posterior pericardiotomy group (group I). Posterior pericardiotomy was not performed in conventional treatment group (group II).

RESULTS

Atrial fibrillation was developed in seven patients (9.3%) in group I and in 24 patients (32%) in group II (P<0.001). Atrial flutter and other supraventricular tachyarrhythmia (SVT) prevalence was not statistically significant. Early pericardial effusion was developed 42.6% (32/75) and 10.6% (8/75), respectively, in group II and group I (P<0.0001), but no late pericardial effusion developed in group I despite seven (9.3%) late pericardial effusions developing in group II (P<0.013).

CONCLUSION

Posterior pericardiotomy is a simple, safe and effective technique for reducing not only the prevalence of early pericardial effusion and related atrial fibrillation but also delayed posterior pericardial effusion and tamponade.

The effects of advanced age on the incidence of supraventricular arrhythmias after pneumonectomy in dogs

Because advanced age is the strongest independent risk factor for the development of supraventricular arrhythmias after lung resection, we compared the incidence and premorbid events of supraventricular arrhythmias after pneumonectomy in young and elderly dogs with the aim of better understanding potential age-related arrhythmogenic mechanisms. Right pneumonectomy was performed in 15 male mongrel dogs ("old" > or =8 yr [n = 8], "young" <4 yr [n = 7]) and the electrocardiogram continuously recorded by an implantable telemetry system for 1 wk before euthanizing. After surgery, 7 of 8 older animals (88%) developed a total of 23 episodes of sustained (>30 s) paroxysmal supraventricular tachycardia (SVT), compared with 0 of 7 (0%) young dogs, P = 0.0014. Analysis of heart rate over the 60 min preceding the onset of SVT revealed a progressive increase in sinus rhythm beginning 15 min before the arrhythmia. Comparison of the heart rate and rhythm obtained in younger animals from the corresponding postoperative hour demonstrated that although older animals developed more atrial (P = 0.03) and ventricular premature contractions (P = 0.056) and episodes of nonsustained ventricular tachycardia (P = 0.01), heart rate was similar for both groups until the increase in elderly dogs preceding the onset of SVT. Histologic examination of the atria showed interstitial fibrosis in old but not young animals. In addition, 4 of 8 (50%) elderly animals exhibited an inflammatory response within the atria consistent with acute myo- and epicarditis. We conclude that elderly dogs have an increased supraventricular arrhythmogenic potential within the first week after pneumonectomy than younger animals, perhaps because of increased atrial fibrosis and inflammation. Heart rate analysis before SVT onset suggests that adrenergic predominance was a probable responsible trigger.

IMPLICATIONS

In this canine pneumonectomy model, advanced age was associated with an increased incidence of supraventricular arrhythmias, perhaps because of increased atrial fibrosis and inflammation.

Circadian variation of short-lasting asymptomatic paroxysmal supraventricular tachycardia

This study determines the circadian variation of transient asymptomatic paroxysmal supraventricular tachycardia (PSVT). A total of 416 asymptomatic PSVT episodes (> or = 10 consecutive supraventricular beats) recorded in 62 patients were obtained from Holter monitoring. The incidence of the onset of PSVT was counted at the 1-hour interval. The duration (beats) and rate (beats/min) of PSVT and the preceding heart rate were also evaluated. The circadian variations of the onset, duration, and rate of PSVT were analyzed by the single cosinor method. The incidence of the onset of PSVT showed a significant circadian variation (P = .001); with high incidence in the daytime and low at nighttime. The rate and duration of PSVT also showed significant circadian variation (P = .02), faster and longer in daytime and slower and shorter at night, respectively. The rate (r = .45, P < .001) and duration (r = .22, P < .001) of PSVT correlated significantly with the preceding heart rate. Our findings suggest that the onset and persistence of short-lasting asymptomatic PSVT exhibit a circadian pattern and that autonomic tone might play an important role in the genesis of this form of PSVT.

Pediatric radiofrequency catheter ablation registry success, fluoroscopy time, and complication rate for supraventricular tachycardia: comparison of early and recent eras

INTRODUCTION

To assess changes of success rate, fluoroscopy time, and complication rate for six supraventricular tachycardia pathways/ mechanisms, data from the Pediatric Radiofrequency Catheter Ablation Registry were grouped into two eras (1991-1995; 1996-1999).

METHODS AND RESULTS

Data from the early era and the late era were compared using the Chi-square test for the outcomes of success rate and complication rate and using the Student's t-test for the outcome of mean fluoroscopy time. In the Registry as a whole, ablation failure rates fell from 9.6% in the early era to 4.8% in the recent era, a reduction of 50% overall. Improved success rates were found for posterior septal, right free-wall, and left free-wall pathways and for AV nodal reentry, whereas anterior septal pathways and atrial ectopic-focus tachycardia did not show improvement. Mean fluoroscopy time overall decreased 21% from 50.9 +/- 39.9 minutes to 40.1 +/- 35.1 minutes. Individually, the improvement in fluoroscopy time was found for all but the atrial ectopic-focus tachycardia mechanism. The complication rate decreased from 4.2% to 3.0%, with significant decreases for left free-wall and posterior septal pathways.

CONCLUSION

Patient selection strategies to optimize radiofrequency ablation outcomes in children, which have been based on the previously published Registry data, should be reconsidered in light of these new, updated data. The lack of uniform improvement provides the impetus for further research and development of new approaches and technologic advances so that further improvement can be achieved.

Coexistence of type I atrial flutter and intra-atrial re-entrant tachycardia in patients with surgically corrected congenital heart disease

OBJECTIVES

This study assessed the coexistence of intra-atrial re-entrant tachycardia (IART) and isthmus-dependent atrial flutter (IDAF) in patients presenting with supraventricular tachyarrhythmias after surgical correction of congenital heart disease (CHD).

BACKGROUND

In patients with CHD, atrial tachyarrhythmias may result from IART or IDAF. The frequency with which IART and IDAF coexist is not well defined.

METHODS

Both IDAF and IART were diagnosed in 16 consecutive patients using standard criteria and entrainment mapping. Seven patients had classic atrial flutter morphology on surface electrocardiogram (ECG), whereas nine had atypical morphology.

RESULTS

A total of 24 circuits were identified. Three patients had IDAF only, five had IART only, seven had both, and one had a low right atrial wall tachycardia that could not be entrained. Twenty-two different reentry circuits were ablated. Successful ablation was accomplished in 13 of 14 (93%) IART and 9 of 10 (90%) IDAF circuits. There was one IART recurrence. The slow conduction zone involved the region of the right atriotomy scar in 12 of 14 (86%) IART circuits. No procedural complications and no further recurrences were seen after a mean follow-up of 24 months.

CONCLUSIONS

Both IDAF and IART are the most common mechanisms of atrial re-entrant tachyarrhythmias in patients with surgically corrected CHD, and they frequently coexist. The surface ECG is a poor tool for identifying patients with coexistent arrhythmias. The majority of IART circuits involve the lateral right atrium and may be successfully ablated by creating a lesion extending to the inferior vena cava.

Supraventricular tachycardia vs. Marfan's syndrome

Marfan's syndrome is one of several genetic connective tissue disorders that manifest cardiovascular abnormalities. Paroxysmal supraventricular tachycardia is not one of these manifestations.

Symptomatic atrial arrhythmias in hemodialysis patients

BACKGROUND/AIMS

Cardiac arrhythmias are frequent in hemodialysis patients and can interrupt treatment. However, the frequency and risk factors have remained unclear because previous reports of arrhythmias in dialysis patients have usually been continuous-monitoring studies that looked at all cardiac ectopy regardless of its seriousness.

METHODS

We reviewed retrospectively only symptomatic atrial arrhythmias in a population of 106 maintenance hemodialysis patients over three years, in order to estimate their actual frequency and any risk factors.

RESULTS

Ten patients, seven men and three women, required treatment for atrial arrhythmias (9.4%): four for supraventricular tachycardia, three for atrial flutter, and three for atrial fibrillation. Their mean age was 53.7 +/- 6.1 years; five of them were < or = 40 years. Seven arrhythmias were new, three were recurrences. All but one occurred between 3 and 4 hours of hemodialysis, and dialysis had to be stopped in nine instances. There was no pattern of hypotensive episodes preceding the arrhythmias. Mean serum K+ drawn at the time of the arrhythmias was 3.8 +/- 0.2 mEq/L. Mean plasma intact parathormone was 1128 +/- 417 pg/mL, compared to 454 +/- 58 pg/mL for our entire hemodialysis population (p = .0036). Subsequent echocardiograms showed abnormalities in 9/10 patients: five had left ventricular hypertrophy, six had left atrial enlargement, five had valvular lesions (four mitral regurgitation; one aortic incompetence), and three had ejection fractions <50%. There were four deaths in these patients over the next 14 months, but probably only one was cardiac.

CONCLUSIONS

Serious atrial arrhythmias are common in a hemodialysis population. Risk factors for symptomatic atrial arrhythmias in hemodialysis patients may include hyperparathyroidism and echocardiographic findings of chamber enlargement, valvular lesions, or ventricular dysfunction.

Effects of diltiazem prophylaxis on the incidence and clinical outcome of atrial arrhythmias after thoracic surgery

OBJECTIVES

We sought to determine whether early prophylaxis with an L -type calcium channel blocker reduces the incidence and morbidity associated with atrial fibrillation/flutter and supraventricular tachyarrhythmia after major thoracic operations.

METHODS

In this randomized, double-blind, placebo-controlled study, 330 patients were given either intravenous diltiazem (n = 167) or placebo (n = 163) immediately after lobectomy (> or =60 years) or pneumonectomy (> or =18 years) and orally thereafter for 14 days. The primary end point with respect to efficacy was a sustained (> or =15 minutes) or clinically significant atrial arrhythmia during treatment.

RESULTS

Postoperative atrial arrhythmias (atrial fibrillation/flutter = 60; supraventricular tachyarrhythmias = 5) occurred in 25 (15%) of the 167 patients in the diltiazem group and 40 (25%) of the 163 patients in the placebo group (P = .03). When compared with placebo, diltiazem nearly halved the incidence of clinically significant arrhythmias (17/167 [10%] vs. 31/163 [19%], P = .02). The 2 groups did not differ in the incidence of other major postoperative complications or overall duration or costs of hospitalization. No serious adverse effects caused by diltiazem were seen.

CONCLUSIONS

After major thoracic operations, prophylactic diltiazem reduced the incidence of clinically significant atrial arrhythmias in patients considered at high risk for this complication.