Right ventricular electrode lead implantation via a persistent left superior vena cava. An improved technique.

Persistent left superior vena cava occurs in approximately 0.5% of the population. This may complicate pacemaker implantation by making lead insertion difficult and causing lead instability through the left cephalic vein and the subclavian vein approach. We used a wide loop technique in the right atrium and successfully advanced the lead in the right ventricle apex. A persistent left superior vena cava does not preclude successful lead placement.

Electropharmacologic characteristics and radiofrequency catheter ablation of sustained ventricular tachycardia in patients without structural heart disease.

Twenty-six patients (mean age 39 +/- 17 years) with idiopathic sustained ventricular tachycardia (VT) were included for study. The patients were divided into two groups: group I: 14 patients with VT originating from the right ventricular outflow tract (wide QRS tachycardia with complete left bundle branch block pattern), and group II: 12 patients with VT originating from the left ventricle (wide QRS tachycardia with complete right bundle branch block pattern). Most of the group I patients (11/14) needed isoproterenol to facilitate induction of VT, and were sensitive to both verapamil and adenosine. Eight patients had successful radio-frequency (RF) ablation and were free of VT without any antiarrhythmic drugs. In group II, sustained VT was induced by programmed ventricular stimulation in all the patients (only 3 patients needed isoproterenol for facilitation); verapamil could terminate all the VT but none of the patients responded to adenosine. Eight patients received RF ablation and 6 patients had successful ablation without recurrent tachycardia on a long-term basis. Different sensitivity to adenosine and isoproterenol between right and left ventricular idiopathic VT suggested different underlying mechanisms for both types of VT. The patients who did not receive catheter ablation still had attacks of VT despite antiarrhythmic drug treatment; however, none of these patients had sudden death since the first attack of VT (mean 95 +/- 51 months), suggesting a benign prognosis in idiopathic VT.

Accessory atrioventricular pathway at the antero-medial mitral annulus--electrophysiologic characteristics and radiofrequency catheter ablation: a case report.

Accessory atrioventricular (AV) pathway located at or near the region of aorta-mitral continuity has rarely been mentioned. This report describes one such case with a concealed accessory AV pathway at the anteromedial mitral annulus adjacent to aorta-mitral continuity. The location of the accessory pathway was confirmed by successful radiofrequency catheter ablation. This patient was a 26-year-old male. His 12-lead surface ECG showed no evidence of ventricular preexcitation during sinus rhythm. The earliest retrograde atrial depolarization recorded from the routine catheters was at the His bundle area during ventricular pacing and orthrodromic AV reentrant tachycardia; paradoxically, the earliest left-sided atrial activation recorded from the coronary sinus catheters was at the distal coronary sinus area. The unique retrograde atrial activation sequence over the left atrium and His bundle area was not true for patients with left lateral or anterolateral accessory pathway. During tachycardia, the local electrogram from the successful ablation site showed local VA fusion in the anteromedial mitral annulus. After delivering one pulse of radiofrequency energy (30W), the accessory AV pathway was successfully eliminated without complication. This report presents a concealed left-sided accessory AV pathway at an unusual location. It is very important to describe special electrophysiologic characteristics and ablation technique in this unusual accessory pathway to improve knowledge in the era of interventional electrophysiology.

Plasma lipid profiles and epidemiology of atherosclerotic diseases in Taiwan--a unique experience.

Rapid economic growth in Taiwan is accompanied by changing lifestyles, and the mortality pattern has switched from predominantly infectious diseases to chronic diseases. Age-adjusted mortality from heart disease has increased slowly but steadily. However, mortality from heart disease in Taiwan remains low compared with many other countries. Mortality from the cerebrovascular diseases has decreased gradually. Current age- and sex-specific values of blood cholesterol low density lipoprotein cholesterol (LDL-C) and triglyceride (TG) are, in general, higher than values in mainland China, but lower than those in the NHANES III and PROCAM studies. From 1950 to 1987, percent dietary fat increased from 16% to 36% in Taiwan. However, a high polyunsaturated fat/saturated fat (P/S) ratio (1.3) maintained during this period may in part explain the favorable blood lipid status and low mortality from heart disease. Data from prospective studies are scarce. In case-control studies carried out in Chinese, significantly higher values of TG, CHOL LDL-C, but lower high density lipoprotein cholesterol (HDL-C) levels have often been found in coronary artery disease (CAD) patients than in controls. The percent differences in TG and HDL-C values (20%) were much greater than those of CHOL and LDL-C (3%). A few studies have identified the TG level as an independent risk factor for stroke and CAD in Taiwan, where a moderate to high fat diet with an advantageous P/S ratio is consumed.

Trilinolein reduces infarct size and suppresses ventricular arrhythmias in rats subjected to coronary ligation.

Trilinolein, a triacylglycerol with linoleic acid as the only fatty acid residue in all esterified positions of glycerol, was previously found to improve erythrocyte deformability in vitro. In this study, the in vivo antiarrhythmic and anti-ischemic effects of trilinolein in coronary ligated rats were investigated. Male Sprague-Dawley rats were anaesthetized with urethane. Trilinolein, at dosages ranging from 10(-11) to 10(-7) g/kg, was administered intravenously 15 min before ligation of coronary artery. Also, the effect of trilinolein on arrhythmia was studied by ligating the coronary artery for 30 min, then reperfusing myocardium for 10 min. During the 30-min ischemia, trilinolein reduced not only the number of ectopic beats but also the incidence rate and duration of ventricular tachycardia. At 10(-7) g/kg, trilinolein completely suppressed all ventricular arrhythmias. Ventricular arrhythmias during 10 min reperfusion were also reduced by trilinolein at similar dosages. Furthermore, the effect of trilinolein on infarct size was evaluated by occluding the coronary artery for 4 h before the infarct zone was stained and weighed. In rats subjected to 4 h coronary ligation, pretreatment with 10(-7) g/kg trilinolein at 15 min prior to the coronary ligation significantly reduced infarct size. Trilinolein may protect myocardium against ischemic injury and suppress arrhythmia during ischemia and reperfusion.

Reappraisal of continuous positive airway pressure therapy in acute cardiogenic pulmonary edema. Short-term results and long-term follow-up.

To investigate whether serial incremental continuous positive airway pressure (CPAP) has any short-term or long-term advantages over face-mask oxygen therapy by way of intrapulmonary shunt reduction, 100 patients admitted to the coronary care unit for the treatment of acute cardiogenic pulmonary edema were studied. All patients received Swan-Ganz catheterization. Hemodynamic and pulmonary function parameters were recorded over the next 6 h, and the patients were followed until hospital discharge. All survivors received regular follow-up at 1-month intervals in the outpatient clinic. During the first-stage investigation period (3 h) PaO2 in the CPAP group showed a significant increase, whereas the intrapulmonary shunt and alveolar-arterial oxygen tension gradient (P[A-a]O2) was significantly reduced (p < 0.005). The CPAP group had significantly lower rate-pressure product and higher stroke volume index compared with the control group. The therapeutic failure rate over 6 h was 24% in the CPAP group and 50% in the control group (p < 0.01). The CPAP group had a significantly lower incidence of tracheal intubation and ventilator therapy than the control group; however, there was no significant difference in short-term mortality and hospital stay between the two groups. In conclusion, although study size was not large enough to demonstrate a difference in mortality, CPAP therapy resulted in physiologic cardiovascular and pulmonary function improvement and significantly reduced the need for intubation; however, it did not decrease mortality in patients with acute cardiogenic pulmonary edema, and a much larger study is needed to investigate this possibility.

Accessory atrioventricular pathways and atrioventricular nodal reentrant tachycardia in teenagers. Electrophysiologic characteristics and radiofrequency catheter ablation.

UNLABELLED: Accessory pathway-mediated tachyarrhythmias and AV nodal reentrant tachycardia represent a large portion of supraventricular tachycardia in younger patients. Reports comparing electrophysiologic characteristics and results of radiofrequency ablation between teenagers and adults from the same electrophysiology laboratory are rare, and these deserve further study. This study included 49 teenage patients (mean age 17 +/- 3 years, range from 10 to 20) and 1008 adult patients (mean age 50 +/- 13 years, range from 21 to 92) referred for electrophysiologic study and radiofrequency ablation for treatment of accessory pathway-mediated and AV nodal reentrant tachycardia. The results showed that: (1) mean duration of tachyarrhythmia was shorter in teenagers, but incidences of syncope, cardioversion for hemodynamic compromise and associated cardiovascular diseases were similar in both groups; (2) teenagers had a higher incidence of right-sided free wall accessory pathways (34.1% vs 14.9%, p = 0.048) and better conduction properties of accessory pathways and AV nodal pathways; (3) fast-slow and multiple forms of AV nodal reentrant tachycardia were significantly less frequent (p = 0.026) in teenagers, whereas atrial fibrillation with ventricular preexcitation was common in adults; (4) success rate, incidence of recurrent tachycardia, total procedure time, radiation exposure time and number of radiofrequency pulses for successful ablation did not differ significantly between teenagers and adults. IN CONCLUSION: (1) different electrophysiologic characteristics were found between teenagers and adults; and (2) radiofrequency ablation was effective and safe in teenagers with paroxysmal supraventricular tachycardia.

Prevalence and subtypes of dementia in Taiwan: a community survey of 5297 individuals.

OBJECTIVE: To study the prevalence rate of dementia in Taiwan, the relative frequencies of its subtypes, and its associations with age, education, gender, and residence location. PARTICIPANTS: A total of 2753 men and 2544 women from four urban and four rural communities participated. Their age ranged from 41 to 88 years; 28% of them were at least 65 years old. Their education ranged from 0 to 20 years; 27% of them had less than 1 year of formal schooling. DESIGN: Phase I was a screening survey by trained nurses who administered a Chinese version of the Mini-Mental State Examination, the MMSE-T1, to all participants. Phase II involved the assessment for dementia by neurologists on the 1521 individuals who had scored less than 24 on the 30-point MMSE-T1. MAIN RESULTS: Thirty-one cases of dementia were identified by the DSM-III-R criteria, including 18 cases of Alzheimer's disease, 10 cases of vascular dementia, and three cases of other dementias. The prevalence rate in individuals aged 65 and over was 2.0%. Aging and illiteracy were associated with higher rates of dementia; gender and residence location made no difference. CONCLUSIONS: The prevalence rate of dementia was low in this Chinese population. Consistent with common findings from other parts of the world, a high rate of dementia was associated with older age and illiteracy, and Alzheimer's disease was the most frequent cause.

Incidence, significance, and pharmacological responses of catheter-induced mechanical trauma in patients receiving radiofrequency ablation for supraventricular tachycardia.

BACKGROUND: Catheter-induced mechanical trauma is unfavorable during electrophysiological study. However, its incidence, significance, and pharmacological responses in patients receiving radiofrequency ablation for supraventricular tachycardia have not been investigated. METHODS AND RESULTS: A prospective study was performed in 666 consecutive patients with documented, symptomatic supraventricular tachycardia. All had been referred for electrophysiological study and radiofrequency ablation. Catheter-induced mechanical trauma was defined by either disappearance of or change in preexcitation pattern induced by the electrode catheters or noninducibility of tachycardia after the electrode catheter-induced termination of tachycardia, confirmed by electrophysiological study. Adenosine, isoproterenol, and atropine were serially administered 1 hour after the mechanical trauma to study pharmacological response. "Rescue" radiofrequency ablation was defined as delivery of radiofrequency energy just at the presumed ablation site immediately after the mechanical trauma. Of the 666 patients, 254 had atrioventricular (AV) nodal reentrant tachycardia, 367 patients had accessory pathways, 30 patients had atrial tachycardia, and 15 had atrial flutter. Catheter-induced mechanical trauma occurred in 17 patients (2.6%): 4 patients had AV nodal reentrant tachycardia, 9 had accessory pathways, and 4 had atrial tachycardia. Five patients had such episodes during the placement of electrode catheters and 12, during mapping and ablation procedures. Of the 4 patients with AV nodal reentrant tachycardia, 3 had mechanical trauma on the retrograde fast pathway and 1, on the antegrade slow pathway. In the 9 patients with accessory pathways, those pathways were located in the left free wall in 4 patients, right free wall in 1, right posteroseptum in 1, and right anteroseptum in 3. Atrial tachycardia was more easily traumatized than AV nodal reentrant tachycardia (P < .01) and than accessory pathways (P < .01). The clinical courses of mechanical trauma were variable: 1 patient had spontaneous recovery within 1 week, 5 patients had recurrence of tachycardia within 3 months, and the rest have been free of tachycardia from 3 to 35 months. The recurrence rate was higher in patients with mechanical trauma than in those without (33.3% versus 3.5%, P < .0001) despite rescue radiofrequency ablation given in 7 patients. Pharmacological agents were generally unable to revive the traumatized tissues, and recurrence was unpredictable. CONCLUSIONS: Catheter-induced mechanical trauma was not common in patients receiving radiofrequency ablation for supraventricular tachycardia. Their clinical courses were variable, and pharmacological manipulation offered little assistance. More than half of the patients had long-term cures. However, the recurrence rate was, on the whole, significantly high despite rescue radiofrequency ablation. There is a need for great caution in the placement of electrode catheters in every patient during electrophysiological study and radiofrequency ablation.

Vasodilator therapy in chronic asymptomatic aortic regurgitation: enalapril versus hydralazine therapy.

OBJECTIVES: This study attempted to evaluate the long-term efficacy of enalapril versus hydralazine therapy on left ventricular volume, mass and function as well as on the renin-angiotensin system in chronic asymptomatic aortic regurgitation. BACKGROUND: We tested the hypothesis that early administration of a vasodilator drug might be able to reduce left ventricular dilation and mass expansion. Because the renin-angiotensin system may be activated in chronic aortic regurgitation, early enalapril therapy might be beneficial. METHODS: Between 1990 and 1993, 76 asymptomatic nonrheumatic patients with mild to severe chronic aortic regurgitation were enrolled in a randomized, double-blind trial comparing enalapril with hydralazine. All patients underwent serial noninvasive studies. Seventy patients completed the 12-month follow-up. RESULTS: At 1 year, patients receiving enalapril had a significant reduction in left ventricular end-diastolic and end-systolic volume indexes (124 +/- 15 vs. 108 +/- 17 ml/m2, p < 0.01; 50 +/- 12 vs. 40 +/- 14 ml/m2, p < 0.01, respectively) and mass index (131 +/- 16 vs. 113 +/- 19 g/m2, p < 0.01), whereas hydralazine therapy showed no significant changes. Both regimens not only had a significant reduction in left ventricular mean wall stress but also had a mild increase in exercise duration. Only enalapril therapy achieved a significant inhibition of the renin-angiotensin system, in contrast to hydralazine therapy. Moreover, the multiple r2 value from the analysis for end-diastolic volume index using the two variables of age and treatment drugs was 72.1% (p < 0.01). CONCLUSIONS: Both regimens decrease left ventricular mean wall stress. Enalapril therapy achieves significant left ventricular mass regression, left ventricular end-diastolic and end-systolic volume index reduction and renin-angiotensin system suppression. These findings suggest that early unloading enalapril therapy has the potential to favorably influence the natural history of chronic aortic regurgitation.

Radiofrequency catheter ablation of sustained intraatrial reentrant tachycardia in a patient with mirror-image dextrocardia.

INTRODUCTION: There has been limited experience with radiofrequency catheter ablation in patients with dextrocardia. This report describes a 37-year-old man who had secundum type atrial septal defect, mirror-image dextrocardia, and drug-refractory atrial tachycardia, in whom catheter-mediated radiofrequency energy successfully eliminated the tachycardia without complication. METHODS AND RESULTS: On electrophysiologic study, the atrial tachycardia could be induced and terminated by atrial extrastimulation or rapid atrial pacing. Mixed resetting response pattern and manifest entrainment were also demonstrated. These findings suggested that the mechanism of atrial tachycardia might be related to reentry with an excitable gap. Because of the mirror-image dextrocardia, biplane fluoroscopy was adjusted to the right anterior oblique (RAO) 60 degrees and left anterior oblique (LAO) 30 degrees positions. Inducibility of the tachycardia was completely abolished after the sixth application of radiofrequency current (30 W). It was noted that the successful electrogram preceded the onset of P wave during atrial tachycardia by about 40 msec. CONCLUSION: This report presents another case in which radiofrequency catheter ablation was used in a patient with dextrocardia. Atrial tachycardia in patients with congenital heart disease may be difficult to control pharmacologically; however, the use of radiofrequency catheter ablation could be recommended as an alternative to medication and surgery.

Sustained atrial tachycardia in adult patients. Electrophysiological characteristics, pharmacological response, possible mechanisms, and effects of radiofrequency ablation.

BACKGROUND: Mechanisms and electropharmacological characteristics in adult patients with atrial tachycardia (AT) are not well described. We proposed that a combination of electropharmacological characteristics, recording of monophasic action potential, and effects of radiofrequency ablation could further determine the mechanisms and achieve a new classification in adults with various types of AT because they were important in regard to the correlation between mechanisms and pathophysiology, clinical syndrome, and responses to specific pharmacological or nonpharmacological therapies. METHODS AND RESULTS: Thirty-six patients (11 female, 25 male; mean age, 57 +/- 13 years) with AT were referred for electropharmacological studies and radiofrequency ablation. Resetting response pattern, entrainment phenomenon, recording of monophasic action potential, serial drug test, response to Valsalva maneuver, endocardial mapping technique, and radiofrequency ablation were performed. Seven patients had automatic AT provocable with isoproterenol; neither initiation nor termination was related to programmed electrical stimulation. The other 29 patients had AT initiated or terminated by electrical stimulation and mechanisms related to triggered activity or reentry; nine of them needed isoproterenol to facilitate initiation of AT, associated with delayed afterdepolarization in monophasic action potential. All responded to adenosine (15 to 60 micrograms/kg) and Valsalva maneuver. Dipyridamole terminated AT and decreased the slope of afterdepolarization. Afterdepolarization was not found in the patients with automatic or reentrant AT. In 40 of 41 (98%), AT was ablated successfully, with late recurrence in 2 of 40 (5%) (follow-up, 18 +/- 4 months). CONCLUSIONS: This study demonstrates the diverse mechanisms and electropharmacological characteristics of AT in adults. Furthermore, radiofrequency ablation of various types of AT could achieve high success and low recurrence rates.

Performance on a dementia screening test in relation to demographic variables. Study of 5297 community residents in Taiwan.

OBJECTIVE: To examine the relation between performance on a dementia screening test and the demographic variables of age, education, gender, and urban vs rural residency. DESIGN: Community survey with cluster sampling. SETTING: One urban and one rural community from each of four geographic regions in Taiwan, Republic of China. PARTICIPANTS: A total of 5265 nondemented individuals approximately equally divided between men and women and between urban and rural residency with a range in age from 41 to 88 years and in education from 0 to 20 years. MAIN OUTCOME MEASURE: Score on a Chinese adaptation of the Mini-Mental State Examination. RESULTS: Lower test scores were associated with older age and less education. The decrease in score with age was faster among participants who had never attended school. Better performance by men and by urban residents was found only among participants with fewer than 6 years of schooling. In this group, the magnitudes of sex and residency differences were comparable among those subjects aged 41 to 64 years and those aged 65 to 88 years. Women who had never worked outside of the home performed poorer than those who had worked outside of the home. CONCLUSIONS: The influence of educational background on test performance is most evident in individuals with less education. Commonly used dementia screening tests may be unfair to poorly educated individuals, especially women and rural residents. Efforts should be made to develop ecologically relevant cognitive tests for the intended study populations. To help distinguish test bias from different rates of cognitive decline, the study populations should include individuals in predementia age ranges.

Atrial pacing-induced reverse alternating Wenckebach periods. A common electrophysiologic phenomenon in patients with dual atrioventricular nodal pathways.

Reverse alternating Wenckebach periods (RAWP) have rarely been described, and the significance of dual AV nodal pathways in atrial pacing-induced RAWP is unknown. Forty-five of 50 consecutive patients (M/F = 23/27, mean age 40 +/- 5 years) with common type AV nodal reentrant tachycardia had discontinuous antegrade conduction curves. Atrial pacing revealed that pattern A RAWP (23 patients) had the fourth paced beat conducted over the fast pathway, and pattern B (18 patients) over the slow pathway. Four patients had both pattern A and B RAWP during different pacing cycle lengths. All episodes of atrial pacing-induced RAWP emerged from (or started as) 3:2 AH block, which thereafter were followed by runs of 2:1 AH block. Comparisons between patterns A and B showed (1) maximal atrial pacing cycle length with RAWP was longer in pattern A; (2) A2H2-A1H1 and A4H4-A1H1 were significantly greater in pattern B; (3) A2H2-A4H4 and H2A4/A2H2 were significantly greater in pattern A. It is concluded that atrial pacing-induced RAWP is a common electrophysiologic phenomenon in patients with dual AV nodal pathways. Furthermore, intermittent slow pathway conduction associated with different AnHn and HnAn+2 parameters helped the interpretation of different conduction patterns.

Major coronary sinus abnormalities: identification of occurrence and significance in radiofrequency ablation of supraventricular tachycardia.

Coronary sinus catheterization is important in electrophysiologic study of patients with supraventricular tachycardia. It can provide an anatomic guide for localization of slow atrioventricular nodal pathway and accessory pathways in the posteroseptal area and left-sided atrioventricular ring. However, the morphologic features of the coronary sinus and its significance in patients with supraventricular tachycardia have not been determined. Four hundred eight patients with accessory pathway-mediated tachyarrhythmia and atrioventricular nodal reentrant tachycardia underwent coronary arteriography for a coronary sinus venogram before electrophysiologic study and radiofrequency ablation. The venous phase of left coronary arteriography that delineated the morphologic features of the coronary sinus was carefully evaluated and recorded in multiple projections. Major coronary sinus abnormalities were defined, and they were found in 12 patients (2.9%). Six patients had angulation of the coronary sinus, 4 patients had hypoplasia of the coronary sinus, 1 patient had narrowing of the proximal coronary sinus, and 1 patient had a fistula from persistent left superior vena cava to the coronary sinus. Of 175 patients with atrioventricular nodal reentrant tachycardia, only 1 patient had major coronary sinus abnormalities (proximal angulation), whereas of 233 patients with accessory pathway-mediated tachycardia, 11 patients had major coronary sinus abnormalities (0.6% vs 4.7%, p < 0.05). The accessory pathways in patients with major coronary sinus abnormalities were located exclusively in the left free wall and posteroseptal area. Proper coronary sinus catheterization could be accomplished in 396 patients with a normal coronary sinus, whereas it could be accomplished in only 1 of the 12 patients with major coronary sinus abnormalities (396/396 vs 1/12, p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Accessory pathway and atrioventricular node reentrant tachycardia in elderly patients: clinical features, electrophysiologic characteristics and results of radiofrequency ablation.

OBJECTIVES: This study was designed to evaluate the clinical features, electrophysiologic characteristics and results of radiofrequency ablation in elderly patients with accessory atrioventricular (AV) pathways or AV node reentrant tachycardia. BACKGROUND: Radiofrequency ablation in elderly patients with paroxysmal supraventricular tachycardia has not been well described, and comparative study between elderly and younger patients is limited. METHODS: Electrophysiologic studies and radiofrequency ablation were performed in 92 elderly patients (45 with an accessory pathway, 47 with AV node reentrant tachycardia). RESULTS: The elderly patients had poorer electrophysiologic properties in accessory pathways and dual AV node pathways than those of younger patients. The success rate of radiofrequency ablation was similar in elderly and younger patients. However, elderly patients had more complications (14%) in left-sided accessory pathways. CONCLUSIONS: Radiofrequency ablation in elderly patients with supraventricular tachycardia was effective. However, it must be performed cautiously in those patients with left-sided accessory pathways.

Clinical features and electrophysiologic characteristics of accessory atrioventricular pathways and atrioventricular nodal reentrant tachycardia: comparative study between young and elderly patients.

Information focused on elderly patients with paroxysmal supraventricular tachycardia, and a comparative study between the elderly and younger patients was limited. The aim of this study was to investigate the clinical features and electrophysiologic characteristics in elderly patients (> or = 65 years of age) with accessory atrioventricular pathway-mediated tachyarrhythmia or atrioventricular nodal reentrant tachycardia. Electrophysiologic studies of 45 elderly patients with accessory pathway-mediated tachyarrhythmia and 47 elderly patients with atrioventricular nodal reentrant tachycardia were performed. When compared with younger patients, the elderly patients had a similar incidence of critical clinical manifestation, higher incidence of other cardiac disease or systemic disease, similar inducibility of tachycardia, greater baseline electrophysiologic parameters (sinus node, atrioventricular node, atrium and ventricle), and poorer properties of accessory pathways and dual atrioventricular nodal pathways. These results suggest that conduction properties of accessory pathways and dual atrioventricular nodal pathways were poorer in elderly patients, but similar critical manifestations and tachycardia events were found in elderly and younger patients.