31 August 2010
Iron Deficiency in Heart Failure
Iron plays a key role in human homeostasis. It is essential for growth and survival, and is a vital ingredient in numerous processes including erythropoiesis, oxygen transport and storage, oxidative metabolism in the skeletal and heart muscle, synthesis and degradation of lipids, carbohydrates, DNA and RNA. Important though it is, iron metabolism must be precisely controlled because iron is insoluble and excess levels can be toxic.Iron deficiency is a relatively common nutritional disorder that affects more than one third of the general population, and is often associated with chronic diseases such as inflammatory bowel disease, Parkinson’s disease, rheumatoid diseases and renal failure. Until recently, there has been little interest in the linkage between iron deficiency and the natural course of chronic heart failure (CHF) syndrome. Traditionally iron deficiency has been linked with a presence of anaemia in CHF, and its reported prevalence varies from 20 percent to 70 percent. Recent research carried out at the Military Hospital, Medical University of Wroclaw has now demonstrated that iron deficiency must be viewed in a much broader clinical context, as it also affects at least one-third of non-anaemic CHF patients. The research was led by Doctor Piotr Ponikowski, who said, “Iron deficiency appears to be independent of the severity of CHF symptoms, and occurs irrespective of anaemia. It also seems to be associated with exercise intolerance and leads to a reduced quality of life. Our research shows that it probably constitutes an ominous sign of a poor outcome, independently of the other well-established prognosticators. In light of its high prevalence and clinical consequences, iron deficiency may well be perceived as an attractive therapeutic target in CHF.”Several earlier reports have already shown that, in iron deficient CHF patients, iron repletion can safely improve functional capacity, exercise tolerance and quality of life. Cardiologists should become more aware of the importance of iron deficiency in CHF patients, and be able to evaluate iron status using a combination of simple, clinically relevant parameters of iron metabolism. More studies are needed to evaluate whether correction of iron deficiency in CHF would translate into clinical benefits.
La nutrigenética será clave para un mejor rendimiento del deportista
El catedrático de Nutrición de la Universidad de Navarra, Alfredo Martínez, ha asegurado que la nutrigenética "mejorará el rendimiento de los deportistas y cambiará su forma de competir", ya que, "podrán prever su mejor momento de forma y recuperarse más fácilmente gracias a la alimentación". Así lo ha expuesto el investigador y profesor de Nutrición durante el curso de verano 'Nutrición, alimentos funcionales y actividad física en la promoción de la salud', impartido en la Universidad del País Vasco (UPV), y en la que se refirió a los beneficios de la nutrición basada en los genes.
Según ha informado la Universidad de Navarra en un comunicado, el experto señaló que "una buena combinación de deporte y alimentación mantiene la salud, aumenta el rendimiento y acelera la recuperación". Sin embargo, advirtió de que "no todas las actividades son iguales, tienen la misma intensidad, duración o frecuencia". "Los individuos también nos diferenciamos, en edad, sexo y el estado nutricional previo. Por eso hay muchos aspectos que deben considerarse para una correcta planificación, incluyendo la herencia genética", defendió.
Respecto a los alimentos más convenientes para practicar deporte, destacó que existe consenso en la importancia de los hidratos de carbono como fuente primaria de energía, "aunque hay quien piensa que los niveles de glucógeno no influyen en los resultados deportivos, en muchas disciplinas sí lo hacen". "Un maratoniano, por ejemplo, lo primero que gasta son sus reservas de glucógeno, antes de utilizar otra mezcla de combustible", añadió.
En el caso de las proteínas, el catedrático de Nutrición de la Universidad de Navarra señaló que su valor se complementa con el entrenamiento. "Por ejemplo, Rafael Nadal tiene mucho más desarrollado el brazo izquierdo -es zurdo-, pero las proteínas las toma para los dos brazos. Lo que ocurre es que toma un buen aporte de proteínas y el ejercicio -la hormesis- hace que le sirvan para aumentar la fuerza de la extremidad que más usa", explicó.
Por su parte, los lípidos, explicó el experto, "resultan esenciales para la vida y para el deporte, por sus funciones reguladores, estructurales y energéticas". En su opinión, decir que la grasa "sólo sirve como fuente de energía para ejercicios intensos y prolongados o con bajo nivel de glucógeno resulta por tanto falso, puesto que la usamos en todo momento dentro de la mezcla de nutrientes que nos sirve como combustible".
Angiotensin II antagonists in paroxysmal atrial fibrillation: Results from the ANTIPAF trial
Atrial fibrillation (AF) is the most common cardiac arrhythmia, affecting about 7 million people in Europe. It is a progressive chronic disease in which episodes become more frequent and long-lasting over time. Conventional anti-arrhythmic therapy aims at halting progression and reducing symptoms, but the use of most anti-arrhythmic drugs is compromised by severe side effects, such as pro-arrhythmia or extra-cardiac organ toxicity.
A number of meta-analyses have shown that angiotensin II antagonists (or ARBs) may have the potential to reduce recurrence of AF, with an almost placebo-like tolerability. However, the available evidence from meta-analyses is heterogeneous with respect to the patient populations under investigation, the specific study designs, and the methods used to detect recurrent AF.
The ANTIPAF (ANgiotensin II anTagonists In Paroxysmal Atrial Fibrillation) trial was the first trial to prospectively evaluate the principal hypothesis that the angiotensin II receptor antagonist olmesartan suppresses episodes of paroxysmal AF. The primary endpoint of the trial was the percentage of days with documented episodes of paroxysmal AF throughout 12 months of follow-up. Secondary endpoints included the time to first occurrence of a documented relapse of AF, quality of life, time to first AF recurrence, time to persistent AF, and the number of hospitalisations.
Patients were stratified according to presence of beta-blocker therapy and randomised to placebo or olmesartan (40 mg/day). Concomitant therapy with ARBs, ACE inhibitors, and anti-arrhythmic drugs was prohibited. Patients were followed using daily trans-telephonic ECG recordings (at least one 1-minute ECG/day) independent of symptoms - and were encouraged to submit further tele-ECGs in any case of AF-related symptoms. Follow-up visits were scheduled after 3, 6, 9 and 12 months, which included long-term ECGs, transthoracic echocardiography, laboratory markers, and assessment of quality of life.
425 patients (at least 18 years old) with documented episodes of paroxysmal AF were included from 37 centres in Germany. A total of 87,818 tele-ECGs were analysed during follow-up (44,888 ECGs in the placebo group and 42,930 ECGs in the olmesartan group). Thus, a mean of 207 tele-ECGs were recorded per patient with an average of 1.12 tele-ECGs per patient and day of follow-up.
The study demonstrated no significant difference in the burden of AF (primary endpoint) between both treatment groups. Further secondary outcome parameters such as quality of life, time to first AF recurrence, time to persistent AF, and the number of hospitalisations were also similar between groups. However, the time to prescription of recovery medication (amiodarone) was longer in patients treated with olmesartan than in those receiving placebo.
Commenting on the study results, principal investigator Professor Andreas Götte from St. Vincenz Hospital, Paderborn, Germany, said: "In patients with AF and concomitant structural heart disease such as hypertensive heart disease or systolic heart failure, ARBs are effective adjunct therapies while being highly tolerable. ANTIPAF provides pivotal evidence, however, that ARBs do not reduce the number of AF episodes in patients with paroxysmal AF and without structural heart disease."
A number of meta-analyses have shown that angiotensin II antagonists (or ARBs) may have the potential to reduce recurrence of AF, with an almost placebo-like tolerability. However, the available evidence from meta-analyses is heterogeneous with respect to the patient populations under investigation, the specific study designs, and the methods used to detect recurrent AF.
The ANTIPAF (ANgiotensin II anTagonists In Paroxysmal Atrial Fibrillation) trial was the first trial to prospectively evaluate the principal hypothesis that the angiotensin II receptor antagonist olmesartan suppresses episodes of paroxysmal AF. The primary endpoint of the trial was the percentage of days with documented episodes of paroxysmal AF throughout 12 months of follow-up. Secondary endpoints included the time to first occurrence of a documented relapse of AF, quality of life, time to first AF recurrence, time to persistent AF, and the number of hospitalisations.
Patients were stratified according to presence of beta-blocker therapy and randomised to placebo or olmesartan (40 mg/day). Concomitant therapy with ARBs, ACE inhibitors, and anti-arrhythmic drugs was prohibited. Patients were followed using daily trans-telephonic ECG recordings (at least one 1-minute ECG/day) independent of symptoms - and were encouraged to submit further tele-ECGs in any case of AF-related symptoms. Follow-up visits were scheduled after 3, 6, 9 and 12 months, which included long-term ECGs, transthoracic echocardiography, laboratory markers, and assessment of quality of life.
425 patients (at least 18 years old) with documented episodes of paroxysmal AF were included from 37 centres in Germany. A total of 87,818 tele-ECGs were analysed during follow-up (44,888 ECGs in the placebo group and 42,930 ECGs in the olmesartan group). Thus, a mean of 207 tele-ECGs were recorded per patient with an average of 1.12 tele-ECGs per patient and day of follow-up.
The study demonstrated no significant difference in the burden of AF (primary endpoint) between both treatment groups. Further secondary outcome parameters such as quality of life, time to first AF recurrence, time to persistent AF, and the number of hospitalisations were also similar between groups. However, the time to prescription of recovery medication (amiodarone) was longer in patients treated with olmesartan than in those receiving placebo.
Commenting on the study results, principal investigator Professor Andreas Götte from St. Vincenz Hospital, Paderborn, Germany, said: "In patients with AF and concomitant structural heart disease such as hypertensive heart disease or systolic heart failure, ARBs are effective adjunct therapies while being highly tolerable. ANTIPAF provides pivotal evidence, however, that ARBs do not reduce the number of AF episodes in patients with paroxysmal AF and without structural heart disease."
* The ANTIPAF study was conducted by the German Competence Network on Atrial Fibrillation (AFNET), an interdisciplinary national research network funded by the German Federal Ministry of Education and Research.
AVERROES trial terminated early: apixaban associated with "important" relative risk reduction for stroke and systemic embolism in AF
The phase 3 AVERROES (Apixaban Versus Acetylsalicylic acid (ASA) to Prevent Strokes) trial, designed to show the superiority of apixaban over aspirin for the prevention of stroke or systemic embolism in high-risk atrial fibrillation patients unsuitable for treatment with a vitamin K antagonist (warfarin), was terminated early following a recommendation from the Data Monitoring Committee. Final study visits took place between 1 July and 15 August this year. A predefined interim analysis had shown clear evidence of a clinically important reduction in stroke and systematic embolism and an acceptable safety profile for apixaban compared to aspirin. The principal investigator, Dr Stuart Connolly from Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada, and the study's sponsors accepted the recommendation to terminate the trial.
AVERROES was a double-blind randomised trial which recruited 5600 patients with atrial fibrillation (mean age 70 years) demonstrated or expected to be unsuitable for treatment with a vitamin K antagonist (because of difficulty in controlling treatment effect, increased risk of haemorrhage, patient refusal to take warfarin or intermediate stroke risk). So far, aspirin is the only effective treatment for stroke prevention in patients unsuitable for warfarin.
Apixaban, a Factor Xa inhibitor, has already been investigated for the prevention of deep vein thrombosis, following orthopaedic surgery, and after acute coronary syndrome - but not so far in patients with atrial fibrillation. The AVERROES trial compared the effects of apixaban and aspirin in these patients. Another trial, ARISTOTLE (not yet completed) is studying apixaban against warfarin in patients suitable for warfarin.
The AVERROES study was performed at 520 sites worldwide and recruitment was completed in December 2009. The primary endpoint was a composite of stroke or systemic embolism, while the primary safety endpoint was major haemorrhage. Secondary and tertiary endpoints were a composite of stroke, systemic embolism, myocardial infarction or vascular death, and total death.
At the interim analysis results showed that the annual rate of stroke or systemic embolism (the primary outcome) was 3.9% per year on aspirin and 1.7% per year on apixaban (HR 0.45, p<0.001). The rate of major haemorrhage was 1.4% per year on aspirin and 1.6% per year on apixaban (HR 1.18, p=0.33). The rate of haemorrhagic stroke was 0.2% per year in both treatment groups and there was no evidence of hepatic toxicity or other major adverse events.
Commenting on the results, Dr Connolly said: "The results of AVERROES are truly impressive. The reduction in stroke and systemic embolism is very important and the increased risk of haemorrhage is small. It appears that apixaban will be an excellent treatment for the many patients with atrial fibrillation who are unsuitable for warfarin. These findings will reduce the burden of stroke in society.”
* Atrial fibrillation is a common heart rhythm disorder in which the upper chamber of the heart beats improperly. Patients with AF are at increased risk of stroke because of the formation of blood clots in the upper chamber. The standard therapy for the prevention of stroke and other embolic events in AF is warfarin.
AVERROES was a double-blind randomised trial which recruited 5600 patients with atrial fibrillation (mean age 70 years) demonstrated or expected to be unsuitable for treatment with a vitamin K antagonist (because of difficulty in controlling treatment effect, increased risk of haemorrhage, patient refusal to take warfarin or intermediate stroke risk). So far, aspirin is the only effective treatment for stroke prevention in patients unsuitable for warfarin.
Apixaban, a Factor Xa inhibitor, has already been investigated for the prevention of deep vein thrombosis, following orthopaedic surgery, and after acute coronary syndrome - but not so far in patients with atrial fibrillation. The AVERROES trial compared the effects of apixaban and aspirin in these patients. Another trial, ARISTOTLE (not yet completed) is studying apixaban against warfarin in patients suitable for warfarin.
The AVERROES study was performed at 520 sites worldwide and recruitment was completed in December 2009. The primary endpoint was a composite of stroke or systemic embolism, while the primary safety endpoint was major haemorrhage. Secondary and tertiary endpoints were a composite of stroke, systemic embolism, myocardial infarction or vascular death, and total death.
At the interim analysis results showed that the annual rate of stroke or systemic embolism (the primary outcome) was 3.9% per year on aspirin and 1.7% per year on apixaban (HR 0.45, p<0.001). The rate of major haemorrhage was 1.4% per year on aspirin and 1.6% per year on apixaban (HR 1.18, p=0.33). The rate of haemorrhagic stroke was 0.2% per year in both treatment groups and there was no evidence of hepatic toxicity or other major adverse events.
Commenting on the results, Dr Connolly said: "The results of AVERROES are truly impressive. The reduction in stroke and systemic embolism is very important and the increased risk of haemorrhage is small. It appears that apixaban will be an excellent treatment for the many patients with atrial fibrillation who are unsuitable for warfarin. These findings will reduce the burden of stroke in society.”
* Atrial fibrillation is a common heart rhythm disorder in which the upper chamber of the heart beats improperly. Patients with AF are at increased risk of stroke because of the formation of blood clots in the upper chamber. The standard therapy for the prevention of stroke and other embolic events in AF is warfarin.
Nurses can significantly reduce the risk of recurrent complications in heart patients: results from the RESPONSE trial
A six-month outpatient prevention programme conducted by nurses has resulted in significant and sustained improvements in the control of cardiovascular risk factors, including high cholesterol or high blood pressure, in patients hospitalised for a heart attack or impending heart attack.
The programme, applied in addition to standard medical care, led to the improved adherence to current guidelines on prevention, including lifestyle and compliance with drug treatment. The nurses were able to increase the proportion of patients with good control of risk factors by 40% (defined as at least seven out of nine risk factors on target) and to reduce the calculated risk of dying in the next 10 years by about 17%.
RESPONSE (Randomised Evaluation of Secondary Prevention by Outpatient Nurse SpEcialists) was an 11-centre randomised study designed to quantify the impact of a nurse-co-ordinated outpatient risk management programme on the risk of future clinical events in patients with symptomatic coronary artery disease. The primary endpoint was patient evaluation according to the SCORE risk score at 12 months, with secondary endpoints assessed according to the Framingham risk score and individual risk factors at 12 months follow-up (including lipid profile, glucose, blood pressure, weight, waist circumference, physical activity, healthy diet, alcohol consumption).
In explaining the background to the trial, principal investigator Professor Ron Peters from the Academic Medical Center, Amsterdam, said: "Patients with coronary artery disease are at high risk of recurrent complications and death. Preventive care can effectively reduce this risk, and guidelines have been issued by the American Heart Association/American College of Cardiology and the European Society of Cardiology which target common risk factors for heart disease such as high blood pressure, smoking, and high cholesterol.
"Together, these risk factors are associated with the development of coronary artery disease, which remains the world's leading cause of death. At present, a considerable gap exists between these guidelines and their application in clinical practice. It is widely believed, both by patients and doctors, that the preventive aspect of treatment is given insufficient priority and that new approaches are needed to realise the full benefits of prevention. A short coaching programme by a nurse, on top of usual care, is such a new approach already found promising in primary care."
The RESPONSE trial, which evaluated an outpatient nursing programme in 11 hospital centres in the Netherlands, included 754 patients hospitalised for an acute coronary complication (MI or impending MI). They were randomised to either usual care alone or usual care plus a six-month nursing intervention that included four extra visits to the outpatient clinic. Nurses gave advice on healthy lifestyle (food choices, physical exercise, non-smoking, weight control), and monitored major risk factors, such as blood pressure, cholesterol and sugar levels, and use of preventive medication. The nurses pursued specific targets as defined by the guidelines, and if necessary drug treatment was adjusted in collaboration with treating physicians.
The primary measurement of the study was performed at 12 months, which was six months after the last visit to the nurse. Results showed a significant improvement in risk factor prevalence at the end of the programme, with no loss of effect at 12 months.
Overall, at 12 months after the start of the programme, 35% of patients in the nursing group and 25% of patients in the control group were classified as having good control of risk factors (defined as at least seven out of nine factors on target). This reflects an increase of 40%. Of the risk factors targeted by the intervention, body weight was the least successful. There was no change in weight or waist circumference between baseline and 12 months, with no difference between the two study groups. "This may indicate that weight loss is not a realistic target in the first year after a coronary event," said Professor Peters, "when priority needs to be given to several other risk factors. It remains to be seen if later attempts might be more successful."
When the risk of death over the next ten years was calculated according to the SCORE risk function, the nurses were able to reduce this risk by 17%.
Professor Peters noted that these results were achieved against a background of medical care that was better than expected, with risk factor levels in the study population more favourable than those reported in the literature - and with excellent adherence to medication in both groups. This high level of care in the control group, he added, may have been influenced by participation in the trial.
"The nurse programme was practical and well attended by the patients," he said. "More than 93% of patients attended all visits to the nurse. These findings are very encouraging and support the initiation of prevention programmes by nurses to help patients reduce their risk of future complications."
The programme, applied in addition to standard medical care, led to the improved adherence to current guidelines on prevention, including lifestyle and compliance with drug treatment. The nurses were able to increase the proportion of patients with good control of risk factors by 40% (defined as at least seven out of nine risk factors on target) and to reduce the calculated risk of dying in the next 10 years by about 17%.
RESPONSE (Randomised Evaluation of Secondary Prevention by Outpatient Nurse SpEcialists) was an 11-centre randomised study designed to quantify the impact of a nurse-co-ordinated outpatient risk management programme on the risk of future clinical events in patients with symptomatic coronary artery disease. The primary endpoint was patient evaluation according to the SCORE risk score at 12 months, with secondary endpoints assessed according to the Framingham risk score and individual risk factors at 12 months follow-up (including lipid profile, glucose, blood pressure, weight, waist circumference, physical activity, healthy diet, alcohol consumption).
In explaining the background to the trial, principal investigator Professor Ron Peters from the Academic Medical Center, Amsterdam, said: "Patients with coronary artery disease are at high risk of recurrent complications and death. Preventive care can effectively reduce this risk, and guidelines have been issued by the American Heart Association/American College of Cardiology and the European Society of Cardiology which target common risk factors for heart disease such as high blood pressure, smoking, and high cholesterol.
"Together, these risk factors are associated with the development of coronary artery disease, which remains the world's leading cause of death. At present, a considerable gap exists between these guidelines and their application in clinical practice. It is widely believed, both by patients and doctors, that the preventive aspect of treatment is given insufficient priority and that new approaches are needed to realise the full benefits of prevention. A short coaching programme by a nurse, on top of usual care, is such a new approach already found promising in primary care."
The RESPONSE trial, which evaluated an outpatient nursing programme in 11 hospital centres in the Netherlands, included 754 patients hospitalised for an acute coronary complication (MI or impending MI). They were randomised to either usual care alone or usual care plus a six-month nursing intervention that included four extra visits to the outpatient clinic. Nurses gave advice on healthy lifestyle (food choices, physical exercise, non-smoking, weight control), and monitored major risk factors, such as blood pressure, cholesterol and sugar levels, and use of preventive medication. The nurses pursued specific targets as defined by the guidelines, and if necessary drug treatment was adjusted in collaboration with treating physicians.
The primary measurement of the study was performed at 12 months, which was six months after the last visit to the nurse. Results showed a significant improvement in risk factor prevalence at the end of the programme, with no loss of effect at 12 months.
Overall, at 12 months after the start of the programme, 35% of patients in the nursing group and 25% of patients in the control group were classified as having good control of risk factors (defined as at least seven out of nine factors on target). This reflects an increase of 40%. Of the risk factors targeted by the intervention, body weight was the least successful. There was no change in weight or waist circumference between baseline and 12 months, with no difference between the two study groups. "This may indicate that weight loss is not a realistic target in the first year after a coronary event," said Professor Peters, "when priority needs to be given to several other risk factors. It remains to be seen if later attempts might be more successful."
When the risk of death over the next ten years was calculated according to the SCORE risk function, the nurses were able to reduce this risk by 17%.
Professor Peters noted that these results were achieved against a background of medical care that was better than expected, with risk factor levels in the study population more favourable than those reported in the literature - and with excellent adherence to medication in both groups. This high level of care in the control group, he added, may have been influenced by participation in the trial.
"The nurse programme was practical and well attended by the patients," he said. "More than 93% of patients attended all visits to the nurse. These findings are very encouraging and support the initiation of prevention programmes by nurses to help patients reduce their risk of future complications."
Investigadores norteamericanos encuentran una base genética clave en el asma severo
Investigadores del Hospital Pediátrico de Cincinnati, en Estados Unidos, han identificado una base genética cuya presencia puede determinar la gravedad del asma, según los resultados de un estudio en ratones cuyos resultados se han publicado en la revista 'Nature Immunology'.
La prevalencia del asma ha aumentado en los últimos años y, pese a que existen numerosos factores ambientales que favorecen su aparición, como el humo del tabaco, algunos alérgenos o la contaminación atmosférica, este estudio ha fijado un posible "punto de inflexión molecular" entre la variante más suave y la más agresiva.
La prevalencia del asma ha aumentado en los últimos años y, pese a que existen numerosos factores ambientales que favorecen su aparición, como el humo del tabaco, algunos alérgenos o la contaminación atmosférica, este estudio ha fijado un posible "punto de inflexión molecular" entre la variante más suave y la más agresiva.
De este modo, los autores de este estudio han descubierto que una proteína preinflamatoria, la interleukina-17 (IL-17A), puede ser la principal culpable de los síntomas más graves de esta enfermedad respiratoria.
Según describe la autora del estudio, Marsha Wills-Karps, el proceso de la enfermedad parece comenzar cuando las vías respiratorias se exponen a los alérgenos ambientales, lo que provoca una mala regulación de un gen llamado factor 3 del complemento (C3), que activa una parte del sistema inmune denominada "cascada de activación del complemento".
Esto conduce a la producción exagerada de IL-17A por las células de las vías respiratorias y pone en marcha lo que los científicos describen como un bucle de amplificación, ya que la IL-17A a su vez induce la producción de más C3 en la superficie de las vías respiratorias.
Al continuar el bucle de amplificación por la exposición constante a estos alérgenos, se aumenta la respuesta inflamatoria, involucrando ya a las células T auxiliares y a otras proteínas interleuquinas (IL-13 e IL-23), lo que provoca en último lugar la obstrucción del flujo nasal.
"Este hallazgo puede ser clave en la búsqueda de futuros tratamientos terapéuticas para combatir esta variante, aunque para ello será necesario precisar si es necesario actuar inhibiendo la producción del IL-17A i sobre las C3", asegura Wills-Karp.
Danish trial demonstrates the benefits of dual-chamber pacing over single-lead atrial pacing in treating sick sinus syndrome
DANPACE, a Danish multicentre randomised trial comparing single lead atrial and dual chamber pacing in patients with sick sinus syndrome, concludes that dual chamber pacing, which was associated with lower rates of atrial fibrillation and re-operation, "should be the preferred pacing mode".
Behind the conclusion lies a 20-site study of 1415 subjects with sick sinus syndrome (a variety of arrhythmias caused by a malfunction of the sinus node, the heart's principal pacemaker) referred for their first pacemaker implantation. Pacemakers are routinely used to treat patients suffering from sick sinus syndrome.
The patients were randomised equally to single-lead atrial or dual-chamber pacemakers* and their progress followed for a mean of 6.4 years, producing over 7000 operational years of evidence. Results showed that all-cause mortality rates were similar in both groups, 29.6% in the single-lead atrial pacemaker group and 27.3% in the dual chamber group. However, the prevalence of paroxysmal atrial fibrillation was lower in the dual chamber group than in the single-lead group (HR 0.79, p=0.024), with significantly fewer dual chamber patients requiring pacemaker re-operation during follow-up (HR 0.50, p<0.001).
Summarising the outcome, principal investigator Dr Jens Cosedis Nielsen from the Department of Cardiology, Skejby Hospital in Aarhus, Denmark, said: “The results showed that, when compared with dual-chamber pacing, single-lead atrial pacing was associated with a 27% increase in the risk of developing atrial fibrillation and a doubling of the risk of having to undergo a pacemaker re-operation.
“In prior trials, ventricular stimulation has been found to increase the incidences of atrial fibrillation and heart failure. However, in this patient group we demonstrated for the first time that dual-chamber pacing actually decreases atrial fibrillation and has no influence on the incidence of heart failure when compared with single-lead atrial pacing without ventricular stimulation.”
Behind the conclusion lies a 20-site study of 1415 subjects with sick sinus syndrome (a variety of arrhythmias caused by a malfunction of the sinus node, the heart's principal pacemaker) referred for their first pacemaker implantation. Pacemakers are routinely used to treat patients suffering from sick sinus syndrome.
The patients were randomised equally to single-lead atrial or dual-chamber pacemakers* and their progress followed for a mean of 6.4 years, producing over 7000 operational years of evidence. Results showed that all-cause mortality rates were similar in both groups, 29.6% in the single-lead atrial pacemaker group and 27.3% in the dual chamber group. However, the prevalence of paroxysmal atrial fibrillation was lower in the dual chamber group than in the single-lead group (HR 0.79, p=0.024), with significantly fewer dual chamber patients requiring pacemaker re-operation during follow-up (HR 0.50, p<0.001).
Summarising the outcome, principal investigator Dr Jens Cosedis Nielsen from the Department of Cardiology, Skejby Hospital in Aarhus, Denmark, said: “The results showed that, when compared with dual-chamber pacing, single-lead atrial pacing was associated with a 27% increase in the risk of developing atrial fibrillation and a doubling of the risk of having to undergo a pacemaker re-operation.
“In prior trials, ventricular stimulation has been found to increase the incidences of atrial fibrillation and heart failure. However, in this patient group we demonstrated for the first time that dual-chamber pacing actually decreases atrial fibrillation and has no influence on the incidence of heart failure when compared with single-lead atrial pacing without ventricular stimulation.”
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