Radiofrequency ablation of atrial fibrillation: effectiveness and safety in 102 consecutive patients.
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Atrial Fibrillation↗
Biomedical subjects
P T Mortensen
Publications and source records attributed to P T Mortensen.
Incidence of atrial fibrillation and thromboembolism in a randomised trial of atrial versus dual chamber pacing in 177 patients with sick sinus syndrome.
OBJECTIVE: To analyse the occurrence of atrial fibrillation (AF) and thromboembolism in a randomised comparison of rate adaptive single chamber atrial pacing (AAIR) and dual chamber pacing (DDDR) in patients with sick sinus syndrome and normal atrioventricular (AV) conduction, in which left atrial dilatation and decreased left ventricular fractional shortening had been observed in the DDDR group. METHODS: 177 consecutive patients with sick sinus syndrome (mean (SD) age 74 (9) years, 104 women) were randomly assigned to treatment with one of three pacemakers: AAIR (n = 54), DDDR with a short rate adaptive AV delay (n = 60) (DDDR-s); or DDDR with a fixed long AV delay (n = 63) (DDDR-l). Analysis was intention to treat. RESULTS: Mean follow up was 2.9 (1.1) years. AF at one or more ambulatory visits was significantly less common in the AAIR group (4 (7.4%) v 14 (23.3%) in the DDDR-s group v 11 (17.5%) in the DDDR-l group; p = 0.03, log rank test). The risk of developing AF in the AAIR group compared with the DDDR-s group was significantly decreased after adjustment for brady-tachy syndrome in a Cox regression analysis (relative risk 0.27, 95% confidence interval (CI) 0.09 to 0.83, p = 0.02). The benefit of AAIR was highest among patients with brady-tachy syndrome. Brady-tachy syndrome and a thromboembolic event before pacemaker implantation were independent predictors of thromboembolism during follow up (relative risk 7.5, 95% CI 1.6 to 36.2, p = 0.01, and relative risk 4.7, 95% CI 1.2 to 17.9, p = 0.02, respectively). CONCLUSIONS: During a mean follow up of 2.9 years AAIR was associated with significantly less AF. The beneficial effect of AAIR was still significant after adjustment for brady-tachy syndrome. Brady-tachy syndrome was associated with an increased risk of thromboembolism.
Adult↗
Quality assessment of pacemaker implantations in Denmark.
AIMS: Quality assessment of therapeutic procedures is essential to insure a cost-effective health care system. Pacemaker implantation is a common procedure with more than 500,000 implantations world-wide per year, but the general complication rate is not well described. We studied procedure related complications for all implantations performed in an entire nation over a 3-year period. METHODS AND RESULTS: A prospective study of complications related to 99% of the 5648 primary pacemaker implantations performed in the 12 Danish pacemaker centres in 1997-1999 was carried out. Overall 76% of the patients received a physiological pacemaker system and 91% received the optimal pacing mode according to international guidelines. Perioperative complications requiring reoperation were: haematoma 0.3%, atrial lead related 1.9%, ventricular lead related 1.7%. Late complications requiring reoperation were: infection 02%, atrial lead related 13%, ventricular lead related 1.2%. The complication rate decreased over the study period, but overall the complication rate was higher than expected and showed considerable variation between centres. CONCLUSIONS: Our results demonstrate that sensitive data such as complications related to pacemaker implantations can be collected on a national basis. We suggest that a reoperation rate higher than 3% for atrial as well as ventricular pacing electrodes in the individual implanting centre should cause the centre to evaluate carefully the procedure as well as the performance of the individual implanter.
Adolescent↗
AV block and changes in pacing mode during long-term follow-up of 399 consecutive patients with sick sinus syndrome treated with an AAI/AAIR pacemaker.
This retrospective study included a large cohort of consecutive patients primarily implanted at Skejby University Hospital with an AAI/AAIR pacemaker because of sick sinus syndrome (SSS) from July 1981 to July 1999. The primary aim of the study was to analyze the risk of developing AV block during long-term follow-up. A secondary aim was to study the incidence and reasons for changes in pacing mode caused by other than AV block. A total of 399 patients (231 women, mean age 71 +/- 13.5 years) were identified. Mean follow-up was 4.6 +/- 3.4 years and occurred at death, reoperation with mode change, pacemaker explant, or end of study. During follow-up, 44 patients had a ventricular lead implanted with a mean delay of 2.8 +/- 3.1 years (range 1 day-10.4 years) after the primary implantation. A total of 30 patients received a ventricular lead because of AV block or AF with bradycardia (annual incidence 1.7%). Another 14 patients received a ventricular lead without having documented AV block or AF with pauses (annual incidence 0.8%). The present observational study documents that in patients with SSS treated with AAI/AAIR pacing, AV block requiring implantation of a ventricular lead occurs at a rate of 1.7% per year. It is considered that AAI/AAIR pacing is safe and reliable as treatment for patients with SSS and normal AV conduction.
Adolescent↗
Three dimensional echocardiography documents haemodynamic improvement by biventricular pacing in patients with severe heart failure.
OBJECTIVES: To quantify the short term haemodynamic effects of biventricular pacing in patients with heart failure and left bundle branch block by using three dimensional echocardiography. DESIGN: Three dimensional echocardiography was performed in 15 consecutive heart failure patients (New York Heart Association functional class III or IV) with an implanted biventricular pacing system. Six minute walk tests were performed to investigate the effect of biventricular pacing on exercise capacity. Data were acquired at sinus rhythm and after short term (2-7 days) biventricular pacing. RESULTS: Compared with baseline values, biventricular pacing significantly reduced left ventricular end diastolic volume (EDV) by mean (SD) 4.0 (5.1)% (p < 0.01) and end systolic volume (ESV) by 5.6 (6.4)% (p < 0.02). Mitral regurgitant fraction was significantly reduced by 11 (12.1)% (p < 0.003) and forward stroke volume (FSV) increased by 13.9 (18.6)% (p < 0.02). Exercise capacity was significantly improved with biventricular pacing by 48.4 (43.3)% (p < 0.00001). Regression analyses showed that the percentage increase in FSV independently predicted percentage improvement in walking distance (r(2) = 0.73, p < 0.0002). Both basal QRS duration and QRS narrowing predicted pacing efficacy, showing a significant correlation with %DeltaEDV, %DeltaESV, and %DeltaFSV. CONCLUSIONS: In five of 15 consecutive patients with heart failure and left bundle branch block, biventricular pacing induced a more than 15% increase in FSV, which predicted a more than 25% increase in walking distance and was accompanied by an immediate reduction in left ventricular chamber size and mitral regurgitation.
Adult↗
[Single-chamber atrial pacing is better than single chamber ventricular pacing in patients with sick sinus syndrome. Results of long-term follow up in a prospective randomized study].
In a study of 225 patients with sick sinus syndrome randomized to single chamber atrial pacing (n = 110) or ventricular pacing (n = 115), atrial pacing was associated with less atrial fibrillation and thromboembolism after 3.3 years follow-up. To determine whether this beneficial effect of atrial pacing is maintained at long-term, follow-up was extended. Follow-up visits were at 3 months, 12 months, and then once every year, and included physical examination, ECG, and pacemaker check-up. After 5.5 years follow-up, all-cause mortality, cardiovascular deaths, atrial fibrillation, thromboembolism, and heart failure were significantly less in the atrial group. AV block occurred in four patients in the atrial group. The beneficial effect of atrial pacing observed previously is enhanced substantially after extended follow-up. Patients with sick sinus syndrome should be treated with an atrial pacing system.
Aged↗
Programming a fixed long atrioventricular delay is not effective in preventing ventricular pacing in patients with sick sinus syndrome.
AIM: Most patients with sick sinus syndrome (SSS) and normal atrioventricular (AV) conduction receive dual chamber (DDDR) pacemakers. Programming a long AV delay has been proposed to avoid ventricular pacing. The present study aimed to evaluate ventricular stimulation in SSS patients with DDDR pacemakers with a long AV delay. METHODS AND RESULTS: Thirty eight patients treated with DDDR pacemakers with a fixed long AV delay (300 ms) were studied. Data from the pacemaker event recorder were retrieved after 3 months and every year after implantation. Ten patients underwent 24 h Holter recording. Mean follow-up was 11.9 +/- 8.3 months. Median daily number of paced events in the ventricle was 2659 (25th-75th percentiles: 775-21 315) with a large inter-individual variation. The proportion of paced events in the ventricle correlated weakly with the baseline PQ interval (Spearman's rho 0.331, P = 0.043). In 12/38 patients the mean daily number of paced events in the ventricle exceeded 10,000. During 24 h Holter recording, pacemaker arrhythmias caused by repetitive retrograde atrioventricular conduction, known as VA (ventriculoatrial) conduction, occurred in five out of 10 patients. CONCLUSION: DDDR pacing with a fixed long AV delay is inefficient in reducing ventricular pacing in one third of patients and is associated with a high risk of arrhythmias caused by repetitive retrograde AV conduction, and therefore cannot be recommended for general use in SSS patients.
Aged↗
Arterial thromboembolism in patients with sick sinus syndrome: prediction from pacing mode, atrial fibrillation, and echocardiographic findings.
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.
Aged↗
Atrioventricular conduction during long-term follow-up of patients with sick sinus syndrome.
BACKGROUND: It has been claimed that patients with sick sinus syndrome have an increased risk of developing AV block, but this has never been assessed prospectively. The aim of the present study was to evaluate in a prospective trial AV conduction during the long-term follow-up of patients with sick sinus syndrome. METHODS: Two hundred twenty-five consecutive patients with sick sinus syndrome and intact AV conduction were randomized to undergo single-chamber atrial pacing (110 patients) or single-chamber ventricular pacing (115 patients). Follow-up after 3 months and then yearly included measurement of the PQ interval and, in patients with atrial pacemakers, determination of the atrial stimulus-Q intervals at pacing rates of 100 and 120 bpm. The occurrence of AV block in the atrial group was recorded. During follow-up (mean, 5.5+/-2.4 years), there was no change in PQ interval in either group and no change in atrial stimulus-Q intervals or Wenckebach block point in the atrial group. Four of 110 patients in the atrial group developed grade 2 to 3 AV block that required upgrading of the pacemaker (0.6% per year). Two of these 4 patients had right bundle-branch block at pacemaker implantation. CONCLUSIONS: AV conduction, estimated as PQ interval and atrial stimulus-Q interval at atrial pacing rates of 100 and 120 bpm and the Wenckebach block point, remains stable during long-term follow-up. Thus, treatment with single-chamber atrial pacing is safe and can be recommended to patients with sick sinus syndrome without bundle-branch block.
Aged↗
Heart failure and echocardiographic changes during long-term follow-up of patients with sick sinus syndrome randomized to single-chamber atrial or ventricular pacing.
BACKGROUND: In patients with sick sinus syndrome, choice of pacing mode has been implicated in the development of congestive heart failure. METHODS AND RESULTS: A total of 225 consecutive patients with sick sinus syndrome and intact atrioventricular conduction were randomized to either single-chamber atrial pacing (n = 110) or single-chamber ventricular pacing (n = 115). Clinical assessment included New York Heart Association classification, medication, and M-mode echocardiography before pacemaker implantation, after 3 months, and subsequently once every year. At long-term follow-up (mean, 5.5+/-2.4 years), NYHA class was higher in the ventricular group than in the atrial group (NYHA class I/II/III/IV: 65/44/4/0 versus 84/22/2/1 patients, P=.010). Increase in NYHA class during follow-up was observed in 35 of 113 patients in the ventricular group versus 10 of 109 in the atrial group (P<.0005). Increase in dose of diuretics from randomization to last follow-up was significantly higher in the ventricular group than in the atrial group (21+/-49 versus 8+/-42 mg furosemide/d, P=.033). The left ventricular fractional shortening decreased significantly in the ventricular group (from 0.36+/-0.12 to 0.31+/-0.08, P<.0005) but not in the atrial group (from 0.35+/-0.13 to 0.33+/-0.09, P=.087). The left atrial diameter increased significantly in both treatment groups (ventricular group: from 34+/-7 to 41+/-7 mm, P<.0005; atrial group: from 34+/-6 to 37+/-7 mm, P=.002), but the increase was significantly higher in the ventricular group than in the atrial group (P<.0005). CONCLUSIONS: During long-term follow-up, ventricular pacing is associated with a higher incidence of congestive heart failure and consumption of diuretics than atrial pacing. This is accompanied by a decrease in left ventricular fractional shortening and an increased dilatation of the left atrium in the ventricular paced patients.
Aged↗
Long-term follow-up of patients from a randomised trial of atrial versus ventricular pacing for sick-sinus syndrome.
BACKGROUND: In a previous study of 225 patients with sick-sinus syndrome randomised to either single-chamber atrial pacing (n=110) or single-chamber ventricular pacing (n=115), we found that after a mean follow-up of 3.3 years, atrial pacing was associated with significantly less atrial fibrillation and thromboembolism whereas there was no significant difference in mortality and heart failure between the two groups. We aimed to find out whether this beneficial effect of atrial pacing is maintained during extended follow-up of up to 8 years. METHODS: Follow-up visits for all patients were at 3 months, 12 months, then once a year at which patients had a physical examination, ECG recording, and pacemaker check-up. Endpoints were mortality, cardiovascular death, atrial fibrillation, thromboembolic events, heart failure, and atrioventricular block. Data was analysed on Dec 31, 1996. FINDINGS: At long-term follow-up, 39 patients from the atrial group had died versus 57 from the ventricular group (relative risk 0.66 [95% CI 0.44-0.99]; p=0.045). 19 patients from the atrial group and 39 patients from the ventricular group died from a cardiovascular cause (0.47 [0.27-0.82]; p=0.0065). The cumulative incidences of atrial fibrillation and chronic atrial fibrillation were also significantly lower in the atrial group than in the ventricular group (0.54 [0.33-0.89], p=0.012 and 0.35 [0.16-0.76], p=0.004, respectively). Thromboembolic events occurred in 13 patients in the atrial group and 26 in the ventricular group (0.47 [0.24-0.92], p=0.023). Heart failure was less severe in the atrial group than in the ventricular group (p<0.05). In multivariate analysis, atrial pacing was significantly associated with freedom from thromboembolic events (0.47 [0.24-0.92], p=0.028) and survival from cardiovascular death (0.52 [0.30-0.91], p=0.022), but no longer with overall survival (0.71 [0.46-1.08], p=0.11) or chronic atrial fibrillation (0.45 [0.20-1.05], p=0.063). Atrioventricular block occurred in four patients in the atrial group (0.6% annual risk). INTERPRETATION: The beneficial effect of atrial pacing found in our previous study is enhanced substantially over time. Patients with sick-sinus syndrome should be treated with an atrial rather than ventricular-pacing system because after long-term follow-up, atrial pacing is associated with a significantly higher survival, less atrial fibrillation, fewer thromboembolic complications, less heart failure, and a low-risk of atrioventricular block.
Aged↗
Long-term follow-up of patients treated with implantable cardioverter defibrillators in a Danish centre. Accurrence ICD therpay and patient survivors.
The aim of the this prospective follow-up study was to evaluate long-term survival and implantable cardioverter-defibrillator (ICD) therapy for ventricular tachyarrhythmias in patients treated with an ICD in a Danish centre. A total of 140 consecutive patients (112 men), of which 70.7% had coronary artery disease, received an ICD at Skejby University Hospital between March 1989 and October 1996. Mean age was 55.6 +/- 14.6 years (range 14-78 years). After implantation, 136 of the patients were followed for a median (range) of 17.7 (0.4-74.1) months. Survival, mode of death and incidence of appropriate ICD therapy and therapy due to potential life-threatening ventricular tachyarrhythmia were the main outcome measures. Kaplan-Meier plots representing total survival, cardiac death, sudden cardiac death and first episode of ICD therapy are presented. After 1, 2, 3 and 4 years, respectively, the cumulative incidences of death were 9, 18, 20 and 24%, of cardiac death 4, 11, 14 and 18%, and of sudden cardiac death 2, 3, 6 and 6%. The cumulative incidences of appropriate therapy after 1, 2, 3 and 4 years were 47, 56, 66 and 80%, respectively. The cumulative incidences of cardiac death after the first episode of appropriate therapy were 9, 11, 15 and 20% after 1, 2, 3 and 4 years, respectively. The occurrence of ICD therapy and patient survival in the present study population treated with ICD at a Danish centre was comparable to results published previously from other larger centres. The rate of sudden cardiac death was low and most of our patients received appropriate ICD therapy during follow-up, indicating correct patient selection and probable benefit of the ICD device.
Adult↗
[Treatment with implantable cardioverter-defibrillators. Experiences from Skejby hospital during the period 1989-1994].
The aim of the present study was to evaluate survival and therapy for ventricular tachyarrhythmia in patients treated with implantable cardioverter-defibrillator (ICD)-implantation at Skejby Hospital. Seventy-two patients, of which 54 were male, have received an ICD since 1989. Mean (range) age was 54 (16-74) years. Forty-nine (68%) had ischaemic heart disease. The patients were followed for a median (range) of 14 (1/2-50) months. Kaplan-Meyer plots are presented for total mortality, cardiac mortality, sudden cardiac mortality, appropriate therapy, and therapy for life-threatening tachyarrhythmia. After one, two and three years respectively, mortality was respectively 13, 27, and 32%, cardiac mortality was 5, 19, and 24%, sudden cardiac mortality was 3, 6, and 12%, cumulative incidence of appropriate therapy was 56, 66, and 90%, and cumulative incidence of therapy for life-threatening tachyarrhythmia was 19, 29 and 52%. It is concluded, that the majority of patients treated with an ICD developed ventricular tachyarrhythmia and had appropriate or lifesaving ICD-therapy during follow-up.
Adolescent↗
[Supraventricular tachycardia treated with percutaneous catheter ablation of the arteriovenous conduction system].
Twelve patients with supraventricular tachycardia refractory to medical management were treated with catheter ablation (fulguration) of the atrioventricular (AV) conduction system followed by pacemaker implantation. All 12 patients had initially 3 degrees AV block. In ten patients it was permanent. One patient had a permanent 1 degree AV block and left bundle branch block. In one patient with initial 3 degrees AV block AV conduction resumed. No major complications were seen. At follow-up, the mean observation period was 15 months (range 3-57 months). All ten patients with permanent 3 degrees AV block were free of arrhythmic symptoms and without any medication. The patient with permanent 1 degree AV block was free of symptoms and arrhythmia, but died 16 months after the ablation. The patient with relapse of the AV conduction continued to have arrhythmic symptoms, but ECG did not confirm arrhythmia. It is concluded that catheter induced 3 degrees AV block is a safe and efficient treatment of patients with supraventricular tachycardia refractory to medical treatment.
Adolescent↗
Improved outcome of coronary arterial bypass surgery in a small center after identification and modification of peroperative risk factors.
By uni- and multivariate analysis, predictors of surgical mortality and postoperative angina were identified retrospectively in 189 patients having had coronary arterial bypass surgery over the period 1978-1984. After modification of these risk factors, surgical outcome was followed up in another 178 patients undergoing operation from 1985 to 1987. The surgical mortality of 7% in the first series was closely associated with postoperative signs of acute myocardial injury. All deaths occurred in patients having at least 3 out of 5 pre- and peroperative risk factors: triple vessel/left main coronary arterial disease, incomplete revascularization, no propranolol treatment, Bretschneider cardioplegia other than "HTP"-solution with blood preperfusion and perioperative vasopressor support. The procedures of cardiac protection were modified. St Thomas multidose potassium cardioplegia and general hypothermia were introduced, perioperative propranolol treatment increased and bypass time decreased. Improved cardiac protection with this regime was seen in the patients operated in 1985-1987 when compared with the first series with regard to perioperative vasopressor support (8 vs 33%, P less than 0.001), spontaneous operative defibrillation (72 vs 52%, P less than 0.001), postoperative arrhythmias (20 vs 43%, P less than 0.001), peak levels of serum enzymes (P less than 0.001), myocardial infarction (7 vs 19%, P less than 0.001) and hospital mortality (2 vs 7%, P less than 0.05). The incidence of freedom from symptoms at 3 months was also increased in the patients undergoing operation from 1985 to 1987 (72 vs 61%, P less than 0.05). Even small centers can improve their surgical outcome by carefully analysing their own results and modifying the identified risk factors.
Angina Pectoris↗
Comparison of immediate versus day to day variability of ventricular tachycardia induction by programmed stimulation.
The use of programmed stimulation to assess long-term oral antiarrhythmic drug efficacy for ventricular tachycardia is complicated by the fact that mode of ventricular tachycardia induction varies from day to day in the absence of drug therapy. The purpose of this prospective study was to assess whether mode of ventricular tachycardia induction is more reproducible within one study than from day to day. Thirty-nine consecutive patients with documented sustained ventricular tachyarrhythmias secondary to coronary artery disease underwent three inductions of ventricular tachycardia at 15 min intervals in the absence of drug therapy. A stimulation protocol in which the only major variable was the number of extrastimuli required for tachycardia induction was used. Subsequent day to day variability in mode of tachycardia induction was also assessed in the same patients at two further drug-free inductions at intervals of 5 +/- 2 days. The number of extrastimuli required for tachycardia induction was significantly more reproducible at the immediate repeat studies than from day to day (69% of patients versus 31%, p less than 0.01). From these data, probability tables were derived that show the likelihood that changes in inducibility at subsequent tachycardia inductions are due to chance. The QRS configuration of induced ventricular tachycardia was also more reproducible at the immediate studies (64% versus 26%, p less than 0.01). Basic electrophysiologic and stimulation variables differed over a significantly wider range from day to day than at the immediate studies.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Curative surgical treatment of atrioventricular junctional re-entrant tachycardia by perinodal dissection.
The medical treatment of an atrioventricular junctional (AV-nodal) re-entrant tachycardia (AVJRT) is often ineffective due to failure of response or significant side effects. Recently, reports of curative surgical procedures using either dissection or cryocoagulation in the AV node area with preservation of normal AV conduction, have been published with excellent short term results in small series. The present paper describes our experience of surgical treatment using the dissection method in five patients. In all patients, AVJRT with short retrograde conduction intervals was diagnosed during the pre- and intraoperative electrophysiological studies. The earliest site of atrial activation during tachycardia was seen close to the triangle of Koch, antero-medially to the AV node. Elective open heart surgery was performed and after cold cardioplegic arrest, the right atrial endocardium was incised and the perinodal atrium carefully disconnected from the AV node. After surgery, a tachycardia could not be induced in any of the patients. In a follow-up period of 14-29 months, all patients have been free of symptoms without antiarrhythmic drugs. Early electrophysiological evaluation of patients with supraventricular tachycardia is advocated and in patients with medically refractory AVJRT, surgery is recommended.
Adolescent↗
Lower chronic stimulation threshold in the carbon-tip than in the platinum-tip endocardial electrode: a randomized study.
Seventy-nine patients admitted for VVI pacemaker treatment were randomly given a Siemens-Elema 412 S endocardial electrode (tip material vitreous carbon, tip area 12 mm2) (41 patients) or a Siemens-Elema 415 S endocardial electrode (tip material platinum, tip area 12 mm2) (38 patients). The groups did not differ in age, sex, magnitude of intracardiac signal or indication for pacemaker treatment. Pacing threshold was measured by the vario technique at 3 and 15 months after the implantation. In the group of carbon-tip electrodes and in the group of platinum-tip electrodes stimulation thresholds at implantation were 0.49 +/- 0.10 V and 0.54 +/- 0.14 V (ns), at months 31.40 +/- 0.45 V and 1.57 +/- 0.53 V (ns), and at months 15 1.12 +/- 0.33 V and 1.37 +/- 0.38 V (P = 0.003), respectively. After 1 year, 88% of the patients in the carbon-tip group and 66% (P = 0.04) in the platinum-tip group fulfilled our criteria for reducing pacemaker output from 5.0 V to 2.5 V. In comparable platinum-tip and carbon-tip pacing electrodes, the chronic stimulation threshold was lower in the carbon-tip than in the platinum-tip electrode.
Aged↗