Biomedical subjects

Hung-Fat Tse

Publications and source records attributed to Hung-Fat Tse.

At least 55 records · Page 3Linked to original sources

PubMed2004

Aspirin resistance is associated with a high incidence of myonecrosis after non-urgent percutaneous coronary intervention despite clopidogrel pretreatment.

OBJECTIVES: We sought to investigate the effect of aspirin resistance on the incidence of myonecrosis after non-urgent percutaneous coronary intervention (PCI) among patients pretreated with clopidogrel. BACKGROUND: Oral antiplatelet therapy using aspirin and a thienopyridine is the standard of care for preventing thrombotic complications of PCI. The effect of aspirin resistance on the outcomes of patients undergoing PCI is unknown. METHODS: We used the Ultegra Rapid Platelet Function Assay-ASA (Accumetrics Inc., San Diego, California) to determine aspirin responsiveness of 151 patients scheduled for non-urgent PCI. All patients received a 300-mg loading dose of clopidogrel >12 h before and a 75-mg maintenance dose in the morning of the PCI. The incidence of myonecrosis was measured by creatine kinase-myocardial band (CK-MB) and by troponin I (TnI) elevations after PCI. RESULTS: A total of 29 (19.2%) patients were noted to be aspirin-resistant. There was a significantly higher incidence of female subjects in the aspirin-resistant versus aspirin-sensitive groups. The incidence of any CK-MB elevation was 51.7% in aspirin-resistant patients and 24.6% in aspirin-sensitive patients (p = 0.006). Elevation of TnI was observed in 65.5% of aspirin-resistant patients and 38.5% of aspirin-sensitive patients (p = 0.012). Multivariate analysis revealed aspirin resistance (odds ratio [OR] 2.9; 95% confidence interval [CI] 1.2 to 6.9; p = 0.015) and bifurcation lesion (OR 2.8; 95% CI 1.3 to 6.0; p = 0.007) to be independent predictors of CK-MB elevation after PCI. CONCLUSIONS: Despite adequate pretreatment with clopidogrel, patients with aspirin resistance as measured by a point-of-care assay have an increased risk of myonecrosis following non-urgent PCI.

Aged↗

PubMed2004

Differential effects of tyrosine kinase inhibitors on volume-sensitive chloride current in human atrial myocytes: evidence for dual regulation by Src and EGFR kinases.

To determine whether protein tyrosine kinase (PTK) modulates volume-sensitive chloride current (I(Cl.vol)) in human atrial myocytes and to identify the PTKs involved, we studied the effects of broad-spectrum and selective PTK inhibitors and the protein tyrosine phosphatase (PTP) inhibitor orthovanadate (VO(4)(-3)). I(Cl.vol) evoked by hyposmotic bath solution (0.6-times isosmotic, 0.6T) was enhanced by genistein, a broad-spectrum PTK inhibitor, in a concentration-dependent manner (EC(50) = 22.4 microM); 100 microM genistein stimulated I(Cl.vol) by 122.4 +/- 10.6%. The genistein-stimulated current was inhibited by DIDS (4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, 150 microM) and tamoxifen (20 microM), blockers of I(Cl.vol). Moreover, the current augmented by genistein was volume dependent; it was abolished by hyperosmotic shrinkage in 1.4T, and genistein did not activate Cl(-) current in 1T. In contrast to the stimulatory effects of genistein, 100 microM tyrphostin A23 (AG 18) and A25 (AG 82) inhibited I(Cl.vol) by 38.2 +/- 4.9% and 40.9 +/- 3.4%, respectively. The inactive analogs, daidzein and tyrphostin A63 (AG 43), did not alter I(Cl.vol). In addition, the PTP inhibitor VO(4)(-3) (1 mM) reduced I(Cl.vol) by 53.5 +/- 4.5% (IC(50) = 249.6 microM). Pretreatment with VO(4)(-3) antagonized genistein-induced augmentation and A23- or A25-induced suppression of I(Cl.vol). Furthermore, the selective Src-family PTK inhibitor PP2 (5 microM) stimulated I(Cl.vol), mimicking genistein, whereas the selective EGFR (ErbB-1) kinase inhibitor tyrphostin B56 (AG 556, 25 microM) reduced I(Cl.vol), mimicking A23 and A25. The effects of both PP2 and B56 also were substantially antagonized by pretreatment with VO(4)(-3). The results suggest that I(Cl.vol) is regulated in part by the balance between PTK and PTP activity. Regulation is complex, however. Src and EGFR kinases, distinct soluble and receptor-mediated PTK families, have opposing effects on I(Cl.vol), and multiple target proteins are likely to be involved.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed2004

Clinical characteristics of and long-term outcome in Chinese patients with hypertrophic cardiomyopathy.

BACKGROUND: Data on the phenotypical pattern and natural history of hypertrophic cardiomyopathy in Chinese patients are very limited. The purpose of this study was to describe the clinical characteristics of and long-term outcome in Chinese patients with hypertrophic cardiomyopathy. METHODS: We evaluated 118 Chinese patients (62 male) who were diagnosed with hypertrophic cardiomyopathy at Queen Mary Hospital from 1973 to 2002. Diagnosis was based on the demonstration of left ventricular hypertrophy (wall thickness > or =15 mm during diastole), either in a specific region or with diffuse distribution, using echocardiography or magnetic resonance imaging. Clinical predictors of major cardiovascular events related to hypertrophic cardiomyopathy (cardiovascular death, potentially fatal cardiac arrhythmia, and refractory heart failure requiring cardiac transplantation or percutaneous alcohol septal ablation) were evaluated with univariate and multivariate Cox proportional hazards regression models. RESULTS: The mean (+/- SD) age at presentation was 54 +/- 18 years. During a mean follow-up of 5.8 +/- 4.3 years (range, 1 to 29 years) from presentation, major cardiovascular events related to hypertrophic cardiomyopathy occurred in 19 patients (16%), including 9 deaths. Annual cardiovascular mortality was 1.6%. Fifty-five patients (47%) had one or more cardiovascular complications related to hypertrophic cardiomyopathy, of which atrial fibrillation was the most common (35%, n = 41). The most common type of hypertrophic cardiomyopathy was the apical variant (41%, n = 49). In multivariate analysis, female sex was the only independent predictor of major cardiovascular events related to hypertrophic cardiomyopathy (hazard ratio = 5.86; 95% confidence interval: 1.77 to 7.21; P = 0.007). CONCLUSION: Hypertrophic cardiomyopathy in Chinese patients is characterized by late onset of presentation, a high incidence of the apical form of the condition, and adverse clinical outcome in female patients, which suggest a different phenotypical pattern than in white patients.

Adult↗

PubMed2004

Demonstration of calcium-activated transient outward chloride current and delayed rectifier potassium currents in Swine atrial myocytes.

Cellular electrophysiology is not fully understood in the atrium of pig heart. The objective of the present study was to determine whether transient outward current (I(to)), ultra-rapid delayed rectifier potassium current (I(Kur)), and rapid and slow delayed rectifier K(+) currents (I(Kr) and I(Ks)) were present in pig atrium. The whole-cell patch technique was applied to record membrane currents and action potentials in myocytes isolated from pig atrium. It was found that an I(to) was activated upon depolarization voltage steps to between -10 and +60 mV from -50 mV in pig atrial cells, and the I(to) was sensitive to the inhibition by the blockade of L-type calcium (Ca(2+)) current, showed a "bell-shaped" I-V relationship, typical of I(to2) (i.e. I(Cl.Ca)). The I(to2) was inhibited by the chloride (Cl(-)) channel blocker anthracene-9-carboxylic acid (9-AC, 200 micromol/l) or 4,4'-diisothiocyanostilben-2,2'disulfonic acid (200 micromol/l), and by Cl(-) substitution in the superfusate. I(Kur) was found in pig atrial myocytes, and the current showed properties of weak inward rectification and use- and frequency-dependent reduction. I(Kur) was resistant to tetraethylammonium, but sensitive to inhibition by 4-aminopyridine (4-AP) (IC(50) = 71.7 +/- 3.5 micromol/l). In addition, E-4031-sensitive I(Kr) and chromanol 293B-sensitive I(Ks) were observed in pig atrial myocytes. Blockade of I(to2), I(Kur), I(Kr) or I(Ks) with corresponding blockers significantly prolonged atrial action potentials. These results indicate that Ca(2+)-activated I(to2), 4-AP-sensitive I(Kur), E-4031-sensitive I(Kr), and 293B-sensitive I(Ks) are present in pig atrial myocytes, and these currents play important roles in action potential repolarization of pig atria.

4-Aminopyridine↗

PubMed2004

Future prospects for implantable devices for atrial defibrillation.

The success of the implantable cardioverter defibrillator (ICD) led to the concept of a device that would terminate atrial fibrillation (AF) using an implantable device. Implantable devices for AF are undergoing rapid evolution. Currently used devices combine pacing and cardioversion therapies to prevent and to treat AE Recent studies have shown that these devices are safe and can decrease the incidence of AF and improve quality of life significantly. Implantable devices for atrial defibrillation are likely to have an increasing role in the near future, particularly when they are used in combination with ICD and cardiac resynchronization therapy in which AF is both common and its termination is clinically beneficial.

Atrial Fibrillation↗

PubMed2003

Prevention of atrial fibrillation recurrence by statin therapy in patients with lone atrial fibrillation after successful cardioversion.

The aim of this study was to investigate the effect of statin therapy on arrhythmia recurrence in patients with lone atrial fibrillation (AF). From July 1998 to December 1999, 62 patients with lone persistent AF lasting >/=3 months underwent successful external cardioversion. After a mean follow-up of 44 months, 85% had recurrence of AF. The use of statins was associated with a significant decrease in the risk of arrhythmia recurrence after successful cardioversion of AF. The result of this retrospective study demonstrates that the use of statins in patients with lone AF was associated with a significant decrease in the risk of arrhythmia recurrence after successful cardioversion.

Aged↗

PubMed2003

Endothelial function in obstructive sleep apnea and response to treatment.

Impaired endothelium-dependent vascular relaxation is a prognostic marker of atherosclerosis and cardiovascular disease. We evaluated endothelium-dependent flow-mediated dilation (FMD) and endothelium-independent nitroglycerin (NTG)-induced dilation of the brachial artery with Doppler ultrasound in 28 men with obstructive sleep apnea (OSA) and 12 men without OSA. Subjects with OSA (apnea-hypopnea index; mean +/- SD, 46.0 +/- 14.5) had lower FMD compared with subjects without OSA (5.3 +/- 1.7% vs. 8.3 +/- 1.0%, p < 0.001), and major determinants of FMD were the apnea-hypopnea index and age. There was no significant difference in NTG-induced dilation. Subjects with OSA were randomized to nasal continuous positive airway pressure (nCPAP) or observation for 4 weeks. Subjects on nCPAP had significant increase in FMD, whereas those on observation had no change (4.4% vs. -0.8%, difference of 5.2%, p < 0.001). Neither group showed significant change in NTG-induced vasodilation. Eight subjects who used nCPAP for over 3 months were reassessed on withdrawing treatment for 1 week. On nCPAP withdrawal, FMD became lower than during treatment (p = 0.02) and were similar to baseline values. Our findings demonstrated that men with moderate/severe OSA have endothelial dysfunction and treatment with nCPAP could reverse the dysfunction; the effect, however, was dependent on ongoing use.

Adult↗

PubMed2003

Pulmonary vein isolation using transvenous catheter cryoablation for treatment of atrial fibrillation without risk of pulmonary vein stenosis.

OBJECTIVES: We sought to evaluate the efficacy and safety of pulmonary vein (PV) isolation using transvenous cryoablation for the treatment of atrial fibrillation (AF). BACKGROUND: Although electrical isolation of PVs with radiofrequency energy for the treatment of AF is feasible, it is associated with a significant risk of PV stenosis. Cryoablation is a new alternative therapy allowing ablation of tissue while preserving its underlying architecture. METHODS: In 52 patients with paroxysmal (n = 45) or persistent (n = 7) AF, PV isolation using the CryoCor cryoablation system (CyroCor Inc., San Diego, California) with a 10F deflectable transvenous catheter was performed as guided by ostial PV potentials. Cryoablation was applied twice at each targeted site (2.5 to 5 min/application). Computed tomography (CT) of the thorax was performed at baseline and at 3 and 12 months to evaluate for PV stenosis. RESULTS: All targeted PVs were completely isolated in 49 (94%) of 52 of patients. Of 152 PVs targeted, 147 (97%) were successfully isolated (mean 3.0 PVs isolated per patient). After a mean period of 12.4 +/- 5.5 months of follow-up, 37 (71%) of 52 patients had no recurrence of AF or were clinically improved, including 29 patients (56%) who had no recurrence of AF with (n = 11) or without the use of anti-arrhythmic drugs. At 3 and 12 months, the CT scan showed no evidence of PV stenosis associated with cryoablation in any patients. CONCLUSIONS: Transvenous catheter cryoablation is an effective method to create PV electrical isolation for the treatment of AF. A clinically satisfactory result can be achieved in 71% of patients with AF, without the risk of PV stenosis.

Adult↗

PubMed2003

Calcium-activated transient outward chloride current and phase 1 repolarization of swine ventricular action potential.

OBJECTIVE: It is unknown whether 4-aminopyridine- (4-AP-) sensitive transient outward K(+) current (I(to1)) and/or Ca(2+)-activated transient outward Cl(-) current (I(Ca.Cl) or I(to2)) contribute(s) to phase 1 repolarization of pig ventricular action potential (AP). The purpose of the present study was to determine ionic contribution of the phase 1 repolarization of AP in pig ventricle. METHODS: We used whole-cell patch techniques to record APs and membrane currents, and Western immunoblotting analysis to detect expression of I(to1) protein (Kv4.2 or Kv4.3) in pig ventricular myocytes. RESULTS: A transient outward current (I(to)) was activated upon depolarization voltage steps to between -10 and +60 mV from -50 mV in pig ventricular cells, and the I(to) was resistant to 4-AP application, but sensitive to the inhibition by ryanodine (10 micromol/l) and the Ca(2+) channel blockade, and the Cl(-) channel blocker 4,4'-diisothiocyanostilben-2,2'disulfonic acid (DIDS, 150 micromol/l). The current was diminished by external Cl(-) (Cl(-)(o)) replacement and showed a 'bell-shaped' I-V relationship at room temperature, typical of I(to2). No difference in I(to2) was observed in the regional cells from epicardium, midmyocardium, and endocardium of left ventricle. APs showed significant phase 1 and 'spike and dome' in pig ventricular myocytes. The phase 1 and 'spike and dome' of APs were not affected by 4-AP (3 mmol/l), but abolished by replacing Cl(-)(o) and by application of 100 micromol/l DIDS, suggesting I(to2) contribution. Western immunoblotting analysis showed no evidence for the expression of 4-AP-sensitive I(to1) channel protein (Kv4.2 or Kv4.3) in pig ventricular cells. CONCLUSION: The results indicate that 4-AP-sensitive I(to1) is not expressed, and only Ca(2+)-activated I(to2) is present in pig cardiac cells, which contributes importantly to the phase 1 repolarization of ventricular APs in this species.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed2003

Angiogenesis in ischaemic myocardium by intramyocardial autologous bone marrow mononuclear cell implantation.

Results of experimental studies have shown that intramyocardial implantation of bone marrow cells induces neovascularisation and improves heart function after myocardial infarction. Our aim was to test this notion in people. We implanted autologous mononuclear bone marrow cells into the ischaemic myocardium of eight patients with severe ischaemic heart disease as guided by electromechanical mapping with a percutaneous catheter procedure. After 3 months of follow-up, there was improvement in symptoms, myocardial perfusion, and function at the ischaemic region on MRI. Future randomised, controlled studies are required to validate this initial encouraging result.

Aged↗

PubMed2003

Effects of chromanol 293B on transient outward and ultra-rapid delayed rectifier potassium currents in human atrial myocytes.

It is unclear whether chromanol 293B, a selective inhibitor of slow component of delayed rectifier K(+) current (I(Ks)), may affect other K(+) currents in human atrium. With whole-cell patch configuration, we evaluated effects of 293B on transient outward K(+) current (I(to1)) and ultra-rapid delayed rectifier K(+) current (I(Kur)) in isolated human atrial myocytes. It was found that 293B inhibited I(to1) and I(Kur) in a concentration-dependent manner. At 10 microM 293B suppressed I(to1) to 3.4 +/- 0.4 from 5.1 +/- 0.3 pA/pF (P < 0.01), and I(Kur) to 1.5 +/- 0.2 from 2.1 +/- 0.3 pA/pF (P < 0.01) at +50 mV. The inhibition of I(to1) and I(Kur) was independent of depolarizing voltage, and the concentration of 50% inhibition was 31.2 microM for I(to1), and 30.9 microM for I(Kur). 293B blocked I(to1) and I(Kur) with the same concentration range, and the significant effect was observed from the concentration of 1 microM. The maximum inhibitive effect was 88% for I(to1) and 96% for I(Kur) at 250 microM. Voltage dependence of activation and inactivation, and time-dependent recovery from inactivation of I(to1) were not altered by 293B; however, time to peak and time-dependent inactivation of I(to1) was significantly accelerated. The results indicate that 293B significantly inhibits the major repolarization K(+) currents I(to1) and I(Kur) in human atrial myocytes.

Adult↗

PubMed2003

Effect of left ventricular function on long-term left ventricular pacing and sensing threshold.

BACKGROUND: The effect of left ventricular (LV) systolic function on the long-term left ventricular pacing and sensing threshold is unclear. METHODS AND RESULTS: We studied the effect of LV ejection fraction (LVEF) on the LV pacing and sensing threshold in 56 patients (mean age: 70.2 +/- 10.5 years) underwent permanent LV pacing using a self-retaining coronary sinus lead (Model 1055 K, St Jude Medical, USA). In 49 patients, the LV lead was implanted for conventional pacemaker indication (sick sinus syndrome = 14, heart block = 26 or slow atrial fibrillation = 9). The remaining 7 patients were implanted for congestive heart failure. The LV pacing and sensing threshold, and lead impedance were compared between patients with LVEF <40% (Group 1, n = 28) and LVEF >40% (Group 2, n = 28) during implant and at 3-month follow up. The LV pacing lead was successfully implanted in all patients without any lead dislodgement on follow-up. At implant, Group 1 patients had a significant lower R wave amplitude, but similar LV pacing threshold and lead impedance as compared to Group 2. However, at 3-month follow-up, Group 1 patients had a significantly higher LV pacing threshold compared to Group 2 patients. There were no significant differences in the sensing threshold and lead impedance between the two groups. Furthermore, there was also a significant interval increase in LV pacing threshold in Group 1 patients (0.94 +/- 0.12 V) after 3 months, but not in Group 2 patients (0.16 +/- 0.08 V, p < 0.01). CONCLUSIONS: The results of this study suggest that the LV systolic function has a significant impact on the long-term LV pacing threshold. The long-term left ventricular pacing threshold in patients with left ventricular systolic dysfunction increased after implant and was higher than patients with normal left ventricular systolic function.

Aged↗

PubMed2003

Shortening of the sensed AV delay of a dual chamber pacemaker during normal sinus rhythm.

We studied the Medtronic Thera and Kappa 400 dual chamber pacemakers to determine the causes and mechanism of shortening of the sensed AV delay during normal sinus rhythm. When the sensed AV delay shortens to less than its programmed value, it lengthens gradually and returns to its programmed duration after a number of pacing cycles. This behavior is linked to the relatively slow automatic mode switching algorithm (AMS) and was observed when a transient increase in the sensed atrial rate failed to reach the point where AMS was activated and also upon exit from the AMS mode.

Cardiac Pacing, Artificial↗

PubMed2003

Advances in devices for cardiac resynchronization in heart failure.

Patients with advanced heart failure have a high mortality and morbidity despite medical therapy. Depending on the underlying heart disease and severity of heart failure, 3.7 to 52.8% of patients have a QRS complex > or =120 ms who may have interventricular and intraventricular dyssynchrony correctible by cardiac resynchronization therapy (CRT). The latter is usually achieved with biventricular pacing, with the left ventricular lead placed in a tributary of the coronary sinus (CS), with a reported success rate between 88-92%. The technical advances for implantation include preformed guide sheaths to cannulate the CS, over the wire leads with passive fixation mechanism, and surgical placement methods. Device-specific CRT features include optimizing heart failure through insurance of a high percentage of pacing, heart failure monitoring, atrioventricular and interventricular timing, and avoiding double ventricular sensing. Furthermore, arrhythmic co-morbidities of heart failure such as atrial fibrillation and ventricular tachyarrhythmias can also be managed. Recent prospective trials suggest that there is a 30% reduction in heart failure hospitalization with CRT, and preliminary results suggest a survival benefit with CRT and implantable cardioverter defibrillator over optimal medical therapy.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2003

Does sinus rhythm beget sinus rhythm? Effects of prompt cardioversion on the frequency and persistence of recurrent atrial fibrillation.

Recent clinical and experimental studies have demonstrated that atrial fibrillation (AF) alters the electrical and mechanical remodeling of the atrium, which subsequently promote the maintenance and recurrence of AF. If atrial remodeling can be prevented with prompt and repeated cardioversion, the likelihood of AF recurrence may be reduced. Recent clinical studies have demonstrated that the strategies of transesophageal echocardiography facilitated early cardioversion and early repeated cardioversion may be clinically valuable in some patients who have persistent AF and recurrence of arrhythmia after the initial cardioversion. Furthermore, the use an implantable atrial defibrillator (IAD) for early repeated device-based cardioversion to maintain sinus rhythm appears to be safe and clinically feasible. Early cardioversion by IAD reduces AF burden, reverses atrial remodeling and prevents subsequent AF recurrence in selected patients without structural heart disease implanted with this device, indicating possible "sinus rhythm begets sinus rhythm". Despite encouraging initial observations, further long-term clinical studies in a larger patient population are needed to confirm this finding. Furthermore, whether the use of IAD in the fully automatic mode to provide immediate termination of AF episodes could intensify the potential beneficial effect and the clinical efficacy of this approach in patients with structural heart disease needs to be evaluated.

Atrial Fibrillation↗

PubMed2003

Impedance cardiography for atrioventricular interval optimization during permanent left ventricular pacing.

Left ventricular (LV) pacing is increasingly used in the management of congestive heart failure. Optimization of the atrioventricular (AV) interval is essential to maximize the hemodynamic benefits of this therapy. Although Doppler echocardiography (echo) is the most widely used method, it is time-consuming, expensive, and operator-dependent. We examined the value of an impedance cardiography (IC)-based method of cardiac output (CO) measurement to optimize the AV interval in 5 men and 1 woman (mean age = 72 +/- 11 years) during permanent LV pacing with a 4.8 Fr unipolar coronary sinus pacing lead. Simultaneous measurements of CO by IC and echo were performed at AV intervals of 50, 80, 110, 150, 180, and 225 ms during DDD pacing at 85 beats/min. The optimal AV interval varied between 110 and 180 ms. In 5 of 6 patients (83%), the optimal AV interval by echo and IC was identical. While CO measurements were higher with IC than with echo (6.1 +/- 0.4 L/min vs 4.7 +/- 0.3 L/min, P < 0.05), CO measurements by IC and echo were closely correlated r = 0.67, P < 0.001). In conclusion, our initial experience suggests that IC is a reliable method of AV interval optimization during LV pacing. IC and echo measurements of CO during LV pacing were closely correlated.

Aged↗

PubMed2003

Dose-response relationship for successful internal atrial defibrillation.

The dose-response relationship for successful defibrillation has been determined in man for the ventricle but not for the atrium. The purpose of this study was to determine the dose-response relationship for internal atrial defibrillation in humans. Seventy-seven consecutive patients underwent internal atrial defibrillation for acute (n = 14) or chronic AF (n = 63). Shocks were delivered in 40-V increments between electrodes positioned in the coronary sinus and the right atrium until successful conversion or a maximum of 400 V was reached. The shock strength versus success of shock data were subjected to a Kaplan-Meier survival analysis combined with a nonparametric probability analysis to arrive at the dose-response relationship. Using this relationship, comparisons were made between acute and chronic AF and clinical relevant conversion percentages (20, 50, 80 and 95%) were estimated and were compared with the conventional mean threshold. There were significant dose-response relationships in both patients groups (P < 0.05). The Kaplan-Meier analysis comparing patients with chronic and acute AF showed significant differences in their dose-response relationships (P < 0.001). The estimated shock intensity for 95% conversion in patients with acute and chronic AF was 279 V (2.9 J) and 433 V (6.6 J), respectively (P < 0.001). The conventional mean defibrillation threshold in patients with acute (192 +/- 15 V. 1.4 +/- 0.2 J) and chronic AF (343 +/- 8 V, 4.4 +/- 0.2 J) predicted the 60% and 45% chance of successful conversion, respectively. In conclusion, this study demonstrates that single shock conversion data can be used to determine a dose-response relationship, which can be used to estimate the shock intensity required for specific successful atrial defibrillation efficacy and to compare different clinical factors that affect defibrillation efficacy.

Aged↗

PubMed2003

Clinical predictors and time course of arrhythmia recurrence in patients with early reinitiation of atrial fibrillation after successful internal cardioversion.

Early reinitiation of atrial fibrillation (ERAF) was commonly observed after successful electrical cardioversion, however, the effect of ERAF on the subsequent time course of arrhythmia recurrence remains unclear. The aim of this study was to evaluate the clinical predictors and time course of AF recurrence with respect to the occurrence of ERAF after successful cardioversion. The clinical predictors and time course of AF recurrence were prospectively evaluated in 124 patients (94 men, 30 women; mean age 65 +/- 9 years) with persistent AF (mean AF duration 36 +/- 40 months), who underwent internal cardioversion. After cardioversion, all patients received treatment with sotalol and were monitored for AF recurrence. Successful restoration of sinus rhythm was achieved in 104 (84%) of 124 patients. ERAF was observed in 28 (27%) of 104 patients in whom 26 of them were successfully treated acutely with intravenous sotalol and repeated cardioversion. After a mean follow-up of 26 months, 29 (28%) of 104 patients remained in sinus rhythm. Kaplan-Meier analysis revealed a significantly poorer outcome with regard to the recurrence of AF in patients with ERAF (hazard ratio 1.7,P = 0.03) and in those with AF for more than 3 years (hazard ratio 1.6,P = 0.03). Despite treatment with sotalol, patients with ERAF had a significantly higher AF recurrence rate within the first day (13/26 [50%] vs 12/76 [16%],P < 0.01), but not during long-term follow-up (21/26 [81%] vs 52/76 [68%],P = 0.3). In contrast, patients with AF for more than 3 years had a similar AF recurrence rate within the first day (7/29 [24%] vs 18/73 [25%],P = 1.0), but a significantly higher recurrence rate during long-term follow-up (27/29 [93%] vs 46/73 [37%],P < 0.01). In conclusion, the occurrence of ERAF and long AF duration were independent predictors for AF recurrence after successful internal cardioversion. The difference in the time course of AF recurrence in patients with ERAF from those with long AF duration suggests distinct arrhythmogenic mechanisms.

Aged↗