Arterial thromboembolism in patients with sick sinus syndrome: prediction from pacing mode, atrial fibrillation, and echocardiographic findings.
(17/5583)
OBJECTIVE: To evaluate whether thromboembolism in sick sinus syndrome can be predicted by pacing mode, atrial fibrillation, or echocardiographic findings. METHODS: Patients were randomised to single chamber atrial (n = 110) or ventricular (n = 115) pacing. They were divided into subgroups with and without brady-tachy syndrome at time of randomisation. The occurrence of atrial fibrillation and thromboembolism during follow up were investigated and compared with echocardiographic findings. RESULTS: The annual risk of thromboembolism was 5.8% in patients with brady-tachy syndrome randomised to ventricular pacing, 3.2% in patients without brady-tachy syndrome randomised to ventricular pacing, 3% in patients with brady-tachy syndrome randomised to atrial pacing, and 1.5% in patients without brady-tachy syndrome randomised to atrial pacing. In atrial paced patients without brady-tachy syndrome at randomisation and without atrial fibrillation during follow up, the annual risk of thromboembolism was 1.4%. Left atrial size measured by M mode echocardiography was of no value in predicting thromboembolism. CONCLUSIONS: Arterial thromboembolism in patients with sick sinus syndrome is very common and is associated primarily with brady-tachy syndrome at randomisation and with ventricular pacing. The risk of thromboembolism is small in atrial paced patients in whom atrial fibrillation has never been documented. (+info)
Prospective randomized study of ablation and pacing versus medical therapy for paroxysmal atrial fibrillation: effects of pacing mode and mode-switch algorithm.
(18/5583)
BACKGROUND: Atrioventricular (AV) node ablation and pacing has become accepted therapy for drug-refractory paroxysmal atrial fibrillation (PAF). However, few data demonstrate its superiority over continued medical therapy. The influence of pacing mode and mode-switch algorithm has not been investigated. METHODS AND RESULTS: Symptomatic patients who had tried >/=2 drugs for PAF were randomized to continue medical therapy (n=19) or AV junction ablation and implantation of dual-chamber mode-switching (DDDR/MS) pacemakers (slow algorithm [n=19] or fast algorithm [n=18]). Follow-up over 18 weeks was at 6-week intervals and used quality-of-life questionnaires (Psychological General Well Being [PGWB], McMaster Health Index [MHI], cardiac symptom score), exercise testing, echocardiography, and Holter monitoring. Paced patients were randomized to DDDR/MS or VVIR and subsequently crossed over. Ablation and DDDR/MS pacing produced better scores than drug therapy for overall symptoms (-41%, P<0.01), palpitations (-58%, P=0. 0001), and dyspnea (-37%, P<0.05). Changes in score from baseline were better with ablation and DDDR/MS pacing for overall symptoms (-48% versus -4%, P<0.005), palpitation (-62% versus -5%, P<0.001), dyspnea (-44% versus -3%, P<0.005), and PGWB (+12% versus +0.5%, P<0. 05). DDDR/MS was better than VVIR pacing for overall symptoms (-21%, P<0.05), dyspnea (-30%, P<0.005), and MHI (+5%, P<0.03). There were no differences between algorithms. More patients developed persistent AF with ablation and pacing than with drugs at 6 weeks (12 of 37 versus 0 of 19, P<0.01). CONCLUSIONS: Ablation and DDDR/MS pacing produces more symptomatic benefit than medical therapy or ablation and VVIR pacing but may result in early development of persistent AF. (+info)
The cost-effectiveness of ibutilide versus electrical cardioversion in the conversion of atrial fibrillation and flutter to normal rhythm.
(19/5583)
Atrial fibrillation and atrial flutter are cardiac rhythm disorders that are often symptomatic and may interfere with the heart's function, limiting its effectiveness. These arrhythmias are responsible for a large number of hospitalizations at a significant cost to the healthcare system. Electrical cardioversion (EC) is the most common nonpharmacologic intervention used to convert atrial fibrillation and atrial flutter to normal rhythm. Electrical cardioversion is highly successful in converting patients to normal rhythm; however, it is more traumatic and resource intensive than pharmacologic treatment. Recently, a new rapid-acting drug, ibutilide, was approved for the conversion of atrial fibrillation and atrial flutter. Ibutilide is administered through intravenous infusion and does not require anesthetization of the patient, as is required for EC. A decision-tree model was developed to estimate the cost-effectiveness of ibutilide therapy compared with EC therapy. Clinical outcomes were based on a phase III trial of ibutilide, and resource use was based on the literature and physician clinical judgment. A stepped conversion regimen of first-line ibutilide followed by EC for patients who fail to convert is less expensive and has a higher conversion rate than first-line EC. Sensitivity analysis shows that our results are robust to changes in cost and effectiveness estimates. (+info)
Predictors of acute hospital costs for treatment of ischemic stroke in an academic center.
(20/5583)
BACKGROUND AND PURPOSE: We sought to determine predictors of acute hospital costs in patients presenting with acute ischemic stroke to an academic center using a stroke management team to coordinate care. METHODS: Demographic and clinical data were prospectively collected on 191 patients consecutively admitted with acute ischemic stroke. Patients were classified by insurance status, premorbid modified Rankin scale, stroke location, stroke severity (National Institutes of Health Stroke Scale score), and presence of comorbidities. Detailed hospital charge data were converted to cost by application of department-specific cost-to-charge ratios. Physician's fees were not included. A stepwise multiple regression analysis was computed to determine the predictors of total hospital cost. RESULTS: Median length of stay was 6 days (range, 1 to 63 days), and mortality was 3%. Median hospital cost per discharge was $4408 (range, $1199 to $59 799). Fifty percent of costs were for room charges, 19% for stroke evaluation, 21% for medical management, and 7% for acute rehabilitation therapies. Sixteen percent were admitted to an intensive care unit. Length of stay accounted for 43% of the variance in total cost. Other independent predictors of cost included stroke severity, heparin treatment, atrial fibrillation, male sex, ischemic cardiac disease, and premorbid functional status. CONCLUSIONS: We conclude that the major predictors of acute hospital costs of stroke in this environment are length of stay, stroke severity, cardiac disease, male sex, and use of heparin. Room charges accounted for the majority of costs, and attempts to reduce the cost of stroke evaluation would be of marginal value. Efforts to reduce acute costs should be monitored for potential cost shifting or a negative impact on quality of care. (+info)
Aortic plaque in atrial fibrillation: prevalence, predictors, and thromboembolic implications.
(21/5583)
BACKGROUND AND PURPOSE: Thoracic aortic plaque identified by transesophageal echocardiography heightens the risk of stroke associated with atrial fibrillation (AF). We sought to identify the prevalence, predictors, and implications of aortic plaque in patients with nonvalvular AF. METHODS: Thoracic aortic plaque was prospectively sought in 770 persons with AF with the use of transesophageal echocardiography and classified as simple or complex on the basis of thickness >/=4 mm, ulceration, or mobility. Clinical and echocardiographic features of thromboembolism were correlated by multivariate analysis. RESULTS: Aortic plaque was detected in 57% of the cohort, and complex plaque was detected in 25%. Both were found more frequently in the descending than in the proximal aorta. Potentially etiologic patient characteristics independently associated with complex plaque included advanced age, history of hypertension, diabetes, and past or present tobacco use. Comorbidities associated with aortic plaque were prior thromboembolism, increased pulse pressure, ischemic heart disease, stenosis or sclerosis of the aortic valve, mitral annular calcification (>10%), elevated serum creatinine concentration, spontaneous echo contrast in the left atrium or appendage, and left atrial appendage thrombus. The prevalence of complex plaque in patients aged <70 years with <10% mitral annular calcification, without ischemic heart disease, or without pulse pressure >/=65 mm Hg was 4% (95% CI, 1% to 6%). CONCLUSIONS: Aortic plaque is prevalent in patients with AF and is associated with atherosclerosis risk factors and with left atrial stasis or thrombosis, which are themselves independent stroke risk factors. Since the predominant location of complex plaque was in the descending aorta, the role of aortic plaque as a source of embolism in AF is uncertain. (+info)
Inhibitory effects of aprindine on the delayed rectifier K+ current and the muscarinic acetylcholine receptor-operated K+ current in guinea-pig atrial cells.
(22/5583)
In order to clarify the mechanisms by which the class Ib antiarrhythmic drug aprindine shows efficacy against atrial fibrillation (AF), we examined the effects of the drug on the repolarizing K+ currents in guinea-pig atrial cells by use of patch-clamp techniques. We also evaluated the effects of aprindine on experimental AF in isolated guinea-pig hearts. Aprindine (3 microM) inhibited the delayed rectifier K+ current (IK) with little influence on the inward rectifier K+ current (IK1) or the Ca2+ current. Electrophysiological analyses including the envelope of tails test revealed that aprindine preferentially inhibits IKr (rapidly activating component) but not IKs (slowly activating component). The muscarinic acetylcholine receptor-operated K+ current (IK.ACh) was activated by the extracellular application of carbachol (1 microM) or by the intracellular loading of GTPgammaS. Aprindine inhibited the carbachol- and GTPgammaS-induced IK.ACh with the IC50 values of 0.4 and 2.5 microM, respectively. In atrial cells stimulated at 0.2 Hz, aprindine (3 microM) per se prolonged the action potential duration (APD) by 50+/-4%. The drug also reversed the carbachol-induced action potential shortening in a concentration-dependent manner. In isolated hearts, perfusion of carbachol (1 microM) shortened monophasic action potential (MAP) and effective refractory period (ERP), and lowered atrial fibrillation threshold. Addition of aprindine (3 microM) inhibited the induction of AF by prolonging MAP and ERP. We conclude the efficacy of aprindine against AF may be at least in part explained by its inhibitory effects on IKr and IK.ACh. (+info)
Efficacy of nasal continuous positive airway pressure therapy in chronic heart failure: importance of underlying cardiac rhythm.
(23/5583)
BACKGROUND: Some previous reports have indicated beneficial cardiac effects of nasal continuous positive airway pressure (NCPAP) in patients with severe congestive heart failure (CHF), but others have reported deleterious cardiac effects, particularly among patients in atrial fibrillation (AF). The aim of this study was to determine if differences in cardiac rhythm influence the acute cardiac response to NCPAP. METHODS: Eleven consecutive patients with CHF were recruited, six in atrial fibrillation (AF) and five with sinus rhythm (SR). Cardiac index was measured during awake NCPAP application by the thermodilution technique during cardiac catheterisation. NCPAP was applied in a randomised sequence at pressures of 0, 5, and 10 cm H2O with three 30 minute applications separated by 20 minute recovery periods without NCPAP. RESULTS: Significant differences were found between the AF and SR groups for cardiac index responses to NCPAP (p = 0.004, ANOVA) with a fall in cardiac index in the AF group (p = 0.02) and a trend towards an increase in the SR group (p = 0.10). Similar differences were seen between the groups in stroke volume index responses but not in heart rate responses. Changes in systemic vascular resistance were also significantly different between the two groups (p < 0.005, ANOVA), rising in the AF group but falling in the SR group. CONCLUSIONS: These data indicate an important effect of underlying cardiac rhythm on the awake haemodynamic effects of NCPAP in patients with CHF. (+info)
Defibrillation-guided radiofrequency ablation of atrial fibrillation secondary to an atrial focus.
(24/5583)
OBJECTIVES: Our aim was to evaluate a potential focal source of atrial fibrillation (AF) by unmasking spontaneous early reinitiation of AF after transvenous atrial defibrillation (TADF), and to describe a method of using repeated TADF to map and ablate the focus. BACKGROUND: Atrial fibrillation may develop secondary to a rapidly discharging atrial focus that the atria cannot follow synchronously, with suppression of the focus once AF establishes. Focus mapping and radiofrequency (RF) ablation may be curative but is limited if the patient is in AF or if the focus is quiescent. Early reinitiation of AF has been observed following defibrillation, which might have a focal mechanism. METHODS: We performed TADF in patients with drug-refractory lone AF using electrodes in the right atrium (RA) and the coronary sinus. When reproducible early reinitiation of AF within 2 min after TADF was observed that exhibited a potential focal mechanism, both mapping and RF ablation were performed to suppress AF reinitiation. Clinical and ambulatory ECG monitoring was used to assess AF recurrence. RESULTS: A total of 44 lone AF patients (40 men, 4 women; 32 persistent, 12 paroxysmal AF) with a mean age of 58+/-13 years underwent TADF. Sixteen patients had early reinitiation of AF after TADF, nine (20%; 5 paroxysmal) exhibited a pattern of focal reinitiation. Earliest atrial activation was mapped to the right superior (n = 4) and the left superior (n = 3) pulmonary vein, just inside the orifice, in the seven patients who underwent further study. At the onset of AF reinitiation, the site of earliest activation was 86+/-38 ms ahead of the RA reference electrogram. The atrial activities from this site were fragmented and exhibited progressive cycle-length shortening with decremental conduction to the rest of the atrium until AF reinitiated. Radiofrequency ablation at the earliest activation site resulted in suppression of AF reinitiation despite pace-inducibility. Improved clinical outcome was observed over 8+/-4 months' follow-up. CONCLUSIONS: Transvenous atrial defibrillation can help to unmask, map, and ablate a potential atrial focus in patients with paroxysmal and persistent AF. A consistent atrial focus is the cause of early reinitiation of AF in 20% of patients with lone AF, and these patients may benefit from this technique. (+info)