Global Alliance for the Promotion of Physical Activity: the Hamburg Declaration

Non-communicable diseases (NCDs), including coronary heart disease, stroke, hypertension, type 2 diabetes, dementia, depression and cancers, are on the rise worldwide and are often associated with a lack of physical activity (PA). Globally, the levels of PA among individuals are below WHO recommendations. A lack of PA can increase morbidity and mortality, worsen the quality of life and increase the economic burden on individuals and society. In response to this trend, numerous organisations came together under one umbrella in Hamburg, Germany, in April 2021 and signed the 'Hamburg Declaration'. This represented an international commitment to take all necessary actions to increase PA and improve the health of individuals to entire communities. Individuals and organisations are working together as the 'Global Alliance for the Promotion of Physical Activity' to drive long-term individual and population-wide behaviour change by collaborating with all stakeholders in the community: active hospitals, physical activity specialists, community services and healthcare providers, all achieving sustainable health goals for their patients/clients. The 'Hamburg Declaration' calls on national and international policymakers to take concrete action to promote daily PA and exercise at a population level and in healthcare settings.

The effect of BI 409306 on heart rate in healthy volunteers: a randomised, double-blind, placebo-controlled, crossover study

PURPOSE

The potent, selective phosphodiesterase-9A inhibitor BI 409306 may be beneficial for patients with attenuated psychosis syndrome and could prevent relapse in patients with schizophrenia. Transient BI 409306-dependent increases in heart rate (HR) demonstrated previously necessitated cardiac safety characterisation. We evaluated cardiac effects of BI 409306 in healthy volunteers during rest and exercise.

METHODS

In this double-blind, three-way crossover study, volunteers received placebo, BI 409306 50 mg or 200 mg in randomised order (same treatment on Days 1 [resting] and 3 [exercise]). Cardiopulmonary exercise testing was performed twice post treatment on Day 3 of each period. BI 409306-mediated effects on placebo-corrected change from baseline in resting HR (ΔΔHR) were evaluated based on exposure-response analysis and a random coefficient model. Adverse events (AEs) were recorded.

RESULTS

Overall, 19/20 volunteers completed. Resting ΔΔHR versus BI 409306 concentration yielded a slope of 0.0029 beats/min/nmol/L. At the geometric mean (gMean) maximum plasma concentration (C_max) for BI 409306 50 and 200 mg, predicted mean (90% CI) ΔΔHRs were 0.80 (- 0.76, 2.36) and 5.46 (2.44, 8.49) beats/min, respectively. Maximum adjusted mean differences from placebo (90% CI) in resting HR for BI 409306 50 and 200 mg were 3.85 (0.73, 6.97) and 4.93 (1.69, 8.16) beats/min. Maximum differences from placebo in resting HR occurred at/near gMean C_max and returned to baseline after approximately 4 h. The proportion of volunteers with AEs increased with BI 409306 dose.

CONCLUSION

Observed hemodynamic effects following BI 409306 administration were of low amplitude, transient, and followed the pharmacokinetic profile of BI 409306.

Sport mit implantiertem Defibrillator oder Schrittmacher

Die Zahl der Patienten mit implantiertem Kardioverter-Defibrillator (ICD) bzw. Schrittmacher nimmt stetig zu. Daher wird der sportärztlich tätige Kardiologe zunehmend mit der Frage der Sporttauglichkeit von Athleten bzw. sportlich aktiven Menschen mit ICD oder Schrittmacher konfrontiert. Frühere Empfehlungen disqualifizierten die Athleten mit ICD für nahezu jeglichen Leistungssport. Ein Wandel in der Sichtweise, der sich letzten Endes in den aktualisierten amerikanischen und europäischen Leitlinien niederschlug, ergab sich durch die Daten des „ICD Sports Safety“-Registers, in dem die Risiken der Sportteilnahme von Athleten mit leitliniengerechter ICD-Implantation systematisch erfasst wurden. Während der Beobachtungsdauer traten keine tachyarrhythmisch bedingten Todesfälle, extern terminierte Tachyarrhythmien während oder nach der Sportausübung und keine Verletzungen durch rhythmogene Synkopen oder Schockabgaben auf. Ob ein Athlet mit ICD Leistungssport treiben kann, ist gemäß den aktuellen Leitlinien eine Einzelfallentscheidung. Unter gewissen Bedingungen erscheint die Teilnahme am Leistungssport möglich, wobei Pro und Kontra sorgfältig abgewogen und insbesondere im Profisport auch rechtliche Aspekte berücksichtigt werden müssen. Gesundheitssport bei ICD-Trägern ist gemäß der aktuellen Studienlage als sicher anzusehen. Vergleichbar mit dem Leistungssport ist bei der Beurteilung der Sporttauglichkeit vor allem die kardiovaskuläre Grunderkrankung als wichtige Determinante zu beachten, es sollten aber auch ICD-spezifische Überlegungen mit in die individuelle Entscheidung mit einfließen.

Bei Schrittmacherträgern ist die kardiopulmonale Leistungsfähigkeit durch die primär elektrische, bradykardisierende Erkrankung des Herzens und der sich damit in unbehandeltem Zustand in der Regel daraus ergebenden chronotropen Inkompetenz zunächst beeinträchtigt und kann durch den Schrittmacher behoben werden. Das Schrittmacheraggregat bzw. dessen Einstellung ist daher eine wichtige – bei Patienten mit rein elektrischer Erkrankung oftmals entscheidende – Determinante für die kardiopulmonale Leistungsfähigkeit. Die noch nicht aktualisierten europäischen Empfehlungen für die Sporttauglichkeit sind noch relativ restriktiv, wohingegen die neuen amerikanischen Richtlinien weitaus moderater formuliert sind: Die Sporttauglichkeit kann in der Regel erteilt werden, wenn es keine Limitationen hinsichtlich der kardialen Grunderkrankung oder Symptomen gibt, wobei einige schrittmacherspezifische Aspekte beachtet werden müssen.

Lazy Sundays: role of day of the week and reactivity on objectively measured physical activity in older people

Background

The aim of this study was to assess the effect of day of the week and wearing a device (reactivity) on objectively measured physical activity (PA) in older people.

Methods

Walking duration as a measure for PA was recorded from 1333 German community-dwelling older people (≥65 years, 43.8% women) over 5 days using accelerometers (activPAL). Least-square means of PA with 95%-confidence intervals (95%-CI) from multi-level analysis were calculated for each day of the week and each measurement day (days after sensor attachment).

Results

Walking duration on Sundays was significantly lower compared to working days (Sunday vs. Monday-Friday: − 12.8 min (95%-CI: − 14.7; − 10.9)). No statistically significant difference compared to working days was present for Saturdays. The linear slope for measurement day and walking duration was marginal and not statistically significant.

Conclusions

Studies using PA sensors in older people should assess Sundays and working days to adequately determine the activity level of the participants.

Evaluation of left and right ventricular systolic and diastolic electromechanical synchrony in older people: a population-based observational study

It is unknown whether physiological ageing also goes along with electromechanical asynchrony of contraction. Aim of the study was to evaluate synchrony of contraction in older people with ("non-healthy") or without ("healthy") evidence for structural cardiac disease. In 547 persons (age 76.7+/-5.5 years, 306 male, 241 female) recruited from a population-based cohort of the ActiFE-Ulm study including a random sample of people >/=65 years old living in the region of Ulm, Germany, various PW- and TDI-Doppler based markers for asynchrony were obtained by echocardiography. Within a subgroup of 84 healthy subjects, at most minimal systolic and diastolic asynchrony was found. Concerning systolic asynchrony, similar observations were made within the non-healthy subgroup. However, extent of diastolic left ventricular intraventricular asynchrony and also - by tendency - diastolic interventricular asynchrony was increased in comparison to the healthy subgroup. To conclude, no evidence that physiological ageing might go along with relevant left or right ventricular systolic or diastolic electromechanical asynchrony was found in our study. Furthermore, our population-based data support the results from other clinical studies with rather selected cohorts that structural heart diseases might go along with increased diastolic asynchrony.

Accuracy of ECG indices for diagnosis of left ventricular hypertrophy in people >65 years: results from the ActiFE study

BACKGROUND

The detection of left ventricular hypertrophy (LVH) is still a common objective of electrocardiography (ECG) in clinical practice.

AIMS

The aim of our study was to evaluate the accuracy of LVH ECG indices in people older than 65 recruited from a population-based cohort (ActiFE-Ulm study).

METHODS

In 432 subjects (mean age 76.2 ± 5.5 years, 51% male), left ventricular mass was echocardiographically determined (Devereux formula) and indexed (LVMI) to body surface area. Several LVH ECG indices (Lewis voltage, Gubner-Ungerleider voltage, Sokolow-Lyon voltage/product, Cornell voltage/product) were calculated with the help of resting ECG data and compared with the echocardiographic assessment.

RESULTS

Despite echocardiographic signs of LVH [LVMI > 115 (♂) or >95 g/m² (♀)] in 47.5% of all subjects, diagnostic performance of all ECG indices was generally low. Magnitude of all LVH-indices was mainly predicted by frontal QRS axis in multivariate linear regression analysis. In comparison with the literature data from younger subjects, average frontal QRS axis turned counterclockwise.

DISCUSSION AND CONCLUSIONS

Most probably, age-related counterclockwise turn of frontal QRS axis is mainly explanatory for the decreased magnitude of LVH ECG indices and consecutive worse diagnostic performance of these indices in the elderly. ECG indices for detection of LVH have insufficient predictive values in geriatric subjects and should therefore not be used clinically for this purpose. Nevertheless, due to its established relevancy in cardiac risk stratification in this age group, usage of some established ECG indices might keep its significance even in the age of modern cardiac imaging.

Right ventricular function assessed by tissue Doppler echocardiography in older subjects without evidence for structural cardiac disease

The aim of our study was to obtain right ventricular (RV) tissue Doppler imaging (TDI) data in older subjects (n = 95, mean age: 74.5 ± 4.6 years) without evidence of hemodynamically significant structural heart disease recruited from a large population-based cohort (ActiFE-Ulm study). Our data indicate that aging may be accompanied by decreasing RV diastolic function and at most little alterations of RV systolic function. Mean values of all parameters were still within the guideline-suggested reference range with most of them closer to the abnormality thresholds. On an individual basis, respective thresholds were also exceeded in some subjects (almost all parameters <20 %) despite the absence of evidence for structural cardiac disease. RV-TDI is a feasible method for evaluation of RV systolic and diastolic function also in a geriatric population as sufficient TDI data was obtainable in the majority of our participants. Published reference values also seem to be mostly suitable although among older subjects, presumed pathological measures might still be compatible with physiological age-related alterations. Therefore, they always have to be interpreted across the clinical context and in relation to other parameters of morphology and function obtained by other ultrasound imaging techniques (M-mode, B-mode, etc.) in the context of echocardiographic evaluation of the right heart.

Feasibility and effects of a combined adjuvant high-intensity interval/strength training in breast cancer patients: a single-center pilot study

PURPOSE

To evaluate feasibility of an exercise intervention consisting of high-intensity interval endurance and strength training in breast cancer patients.

METHODS

Twenty-six women with nonmetastatic breast cancer were consecutively assigned to the exercise intervention- (n= 15, mean age 51.9 ± 9.8 years) and the control group (n = 11, mean age 56.9 ± 7.0 years). Cardiopulmonary exercise testing that included lactate sampling, one-repetition maximum tests and a HADS-D questionnaire were used to monitor patients both before and after a supervised six weeks period of either combined high-intensity interval endurance and strength training (intervention group, twice a week) or leisure training (control group).

RESULTS

Contrarily to the control group, endurance (mean change of VO₂, _peak 12.0 ± 13.0%) and strength performance (mean change of cumulative load 25.9 ± 11.2%) and quality of life increased in the intervention group. No training-related adverse events were observed.

CONCLUSIONS

Our guided exercise intervention could be used effectively for initiation and improvement of performance capacity and quality of life in breast cancer patients in a relatively short time. This might be especially attractive during medical treatment. Long-term effects have to be evaluated in randomized controlled studies also with a longer follow-up. Implications for Rehabilitation High-intensity interval training allows improvement of aerobic capacity within a comparable short time. Standard leisure training in breast cancer patients is rather suitable for the maintenance of performance capacity and quality of life. Guided high-intensity interval training combined with strength training can be used effectively for the improvement of endurance and strength capacity and also quality of life. After exclusion of contraindications, guided adjuvant high-intensity interval training combined with strength training can be safely used in breast cancer patients.

[Sports cardiology : Overview of relevant clinical topics]

Physical activity is nowadays an established therapeutic principle concerning primary and secondary prevention of cardiovascular diseases; therefore, in internal sports medicine various aspects go beyond basic cardiological knowledge and require special medical expertise (sports cardiology). Acute cardiac risk is increased during physical activity; therefore, physical activity should be individually phased under consideration of the whole clinical situation. Physical training results in a functional adaptation of the cardiovascular system. Moreover, a structural adaptation can also be observed in competitive athletes but a differentiation between athlete's heart and cardiomyopathy is sometimes challenging. Preparticipation screening verifiably reduces the incidence of sudden cardiac death in athletes. Respective recommendations for the required diagnostics have been published and statutory health insurances are increasingly more willing to bear the incurred costs. Statistically, doping is more frequent in performance-orientated leisure time sports than in competitive sports. Drugs which are relevant for doping have partially irreversible cardiac side effects.

The role of sex, adiposity, and gonadectomy in the regulation of irisin secretion

A sexual dimorphism has been reported for the adipo-myokine irisin at rest and in response to exercise. The effects of male and female sex, adiposity, and gonadectomy on irisin secretion have not been investigated before. The objective of this study was to elucidate the effects of sex, adiposity, and gonadectomy in the regulation of irisin secretion as well as PGC-1α/FNDC5 mRNA and protein expression. We hypothesized that a lack of female sex hormones by ovariectomy reduces irisin levels and inhibits skeletal muscle expression of PGC-1α and FNDC5. Circulating irisin was measured in vivo in serum samples of healthy and obese men and women at rest and in response to acute exercise. The effects of gonadectomy on serum irisin, PGC-1α and FNDC5 muscle mRNA, and protein expression were investigated in ovariectomized (OVX) and orchiectomized (ORX) Wistar rats. Serum irisin at rest was not significantly different between men and women (lean or obese). However, in response to acute aerobic exercise, irisin levels increased significantly more in lean women versus men (p ≤ 0.05). In obese individuals, resting irisin concentrations were significantly higher compared to lean subjects (p ≤ 0.001) and the irisin response to acute exercise was blunted. Only the lack of gonadal hormones in OVX but not ORX rats increased serum irisin levels (p ≤ 0.01) and resulted in significantly increased body weight (p ≤ 0.01), adipose tissue content (p ≤ 0.05), muscle FNDC5 mRNA (p ≤ 0.05), and protein (p ≤ 0.01) expression without altering PGC-1α expression. Testosterone treatment in ORX rats leads to increased PGC-1α mRNA content and reduced PGC-1α protein content without affecting FDNC5 expression or serum irisin levels. We show that a sexual dimorphism exists for the acute irisin response to exercise in normal-weight but not in obese subjects. OVX, which is associated with increased adiposity and insulin insensitivity, increases basal FNDC5 expression and serum irisin, without altering PGC-1α expression. This may be an early sign for metabolic disturbances associated with menopause, such as a developing irisin resistance or an attempt of the organism to improve glucose metabolism.

Echocardiographic B-mode evaluation of the right heart in older people: The ActiFE Study

PURPOSE

Right heart B-mode echocardiography reference values have been predominantly obtained in younger age cohorts (<65years). Aims of the study were to describe and evaluate the feasibility of right heart B-mode echocardiography in a large geriatric cohort and to analyze standard parameters in defined subgroups with or without any evidence for structural cardiac disease.

METHODS

ActiFE-Ulm study is a population-based cohort study including a sample of people≥65years old living in the region of Ulm, Germany. Echocardiography including right heart parameters was performed within a cardiovascular follow-up of 688 subjects.

PRINCIPAL RESULTS

Non-obtainability of right heart B-mode data was rather not a consequence of accompanying cardiac diseases or risk factors but of a more obese body composition. Mean values of right heart measurements of our subpopulation of subjects without evidence for structural cardiac disease were continuously higher than those of the guidelines (e.g. mean right ventricular end diastolic area 23.5±5.6cm(2) (males), 20.3±5.0cm(2) (females)). On an individual basis, guideline-suggested abnormality thresholds were also often exceeded, whereas this situation occurred more often in male than in female subjects.

MAJOR CONCLUSIONS

Methodically, right heart B-mode echocardiography in older subjects is challenging. Our results suggest an ageing-associated right heart enlargement. Utilization of published right heart reference values in older adults seems to be problematic and in clinical practice, they always have to be interpreted within the clinical and functional context and in relation to other right heart echocardiographic parameters.

Atrial reverse remodeling: restitution of early tachycardia-induced alterations of atrial ion currents after termination of rapid atrial pacing in rabbits

BACKGROUND AND PURPOSE

Studies report on the reversal of electrophysiological parameters altered by atrial tachycardia after cessation of the latter. However, there is no data concerning reversal of tachycardia-induced alterations of ion currents. Reverse remodeling of atrial ion currents (I(Ca,L), I(to), I(sus)) was studied in our rabbit model of tachycardia-induced electrical remodeling.

METHODS

Three groups each with four animals were built. Rapid atrial pacing (600/min) for 5 days was applied in all groups. Thereafter, different time intervals (5, 10, 20 days) were awaited before the patch clamp experiments.

RESULTS

Similar to I(to) remodeling in our model, within 20 days after cessation of atrial tachycardia, time course of I(to) reverse remodeling was also U-shaped. In contrast, there was no significant recovery of I(Ca,L) which was initially reduced by rapid atrial pacing.

CONCLUSION

Relevance of a missing recovery of I(Ca,L) is likely as this current is closely linked with intracellular calcium handling.

Efficacy of cut-and-sew box isolation of the posterior left atrium for treatment of atrial fibrillation-long-term follow-up after a modified maze procedure

BACKGROUND

Box isolation of the posterior left atrium is one surgical or catheter ablative approach for treating atrial fibrillation (AF). In such cases, incomplete transmurality or recovery of pulmonary vein conduction after the application of various ablative techniques is considered the main reason for the recurrence of postprocedural arrhythmia. The use of solely cut-and-sew box isolation does not have these disadvantages and therefore demonstrates maximum efficacy for this therapeutic approach.

METHODS

We treated 15 patients with both an indication for open heart surgery and AF (2 paroxysmal, 6 short persistent [<12 months], and 7 long persistent [>12 months] cases) with a solely cut-and-sew box lesion. These patients were then retrospectively followed up over the long term with respect to the end point of freedom of atrial tachyarrhythmias >30 seconds.

RESULTS

The median follow-up duration was 42 months (range, 32-84 months). Five (63%) of 8 patients with preoperative paroxysmal or short persistent AF had no arrhythmia recurrence, whereas arrhythmia recurrence was documented in all 7 patients with preoperative long persistent AF.

CONCLUSIONS

Despite reliable transmural isolation with cut-and-sew lesions, we observed long-term arrhythmia recurrence in patients who had preoperative paroxysmal or short persistent AF, suggesting that therapy approaches that are more complex than box isolation might be needed for selected patients to achieve long-term stable sinus rhythm, despite the initially paroxysmal or short persistent character of the arrhythmia. A high rate of recurrence in patients with severe structural heart disease and preoperative long persistent AF might indicate that, in general, isolation of the left posterior atrium alone is not an adequate therapeutic approach for these patients.

[Catheter ablation of paroxysmal atrial fibrillation: extended recommendations considering safety improvements of pulmonary vein isolation with a cryoballoon--Case 11/2011]

HISTORY AND ADMISSION FINDINGS

A 71-year-old, male patient was referred to our clinic for paroxysmal palpitations with dyspnoe and fatigue since four years despite pharmacological treatment with flecainide and bisoprolol.

INVESTIGATIONS

A paroxysmal atrial fibrillation was documented in a 24-hour Holter recording. A bicycle ergometry showed a hypertensive reaction during exercise without any sign of coronary insufficiency. Intracardiac thrombi could by excluded by transesophageal echocardiography.

DIAGNOSIS, TREATMENT AND COURSE

The diagnosos of a drug-refractory paroxysmal atrial fibrillation was made and cryoballoon pulmonary vein isolation was performed. A follow-up 3 months after the ablation disclosed a freedom from atrial fibrillation documented in 7-day Holter recording.

CONCLUSIONS

Compared to pharmacological rhythm control, interventional treatment has been established as more effective therapy for paroxysmal atrial fibrillation. However, patients should be referred to the ablation early enough to avoid structural atrial remodeling and thus transition into persistent or permanent atrial fibrillation. New technical developments e.g. cryoballoon catheter-system simplifies the procedure and has been reported to be effective and safe to use for circumferential pulmonary vein isolation. Should the very promising preclinical data on efficacy and safety of cryothermal energy ablation be confirmed by results of ongoing, controlled trials, the catheter ablation may become the fist-line treatment for all patients with paroxysmal atrial fibrillation.

Effects of dexamethasone and atorvastatin on atrial sodium current and its early tachycardia-induced electrical remodeling in rabbits

PURPOSE

Atrial fibrillation (AF) results in tachycardia-induced ionic remodeling. Pharmacological prevention of tachycardia-induced ionic remodeling not only with "classical" antiarrhythmics but also with drugs which provide a basis for some of the pillars of the so-called "upstream" therapy of AF like corticosteroids or statins has been proposed as a therapeutic strategy. Amongst other ion currents, atrial sodium current I(Na) and its tachycardia-induced alterations play an important role in AF pathophysiology. Thus, effects of a dexamethasone (DT) and atorvastatin treatment (AT) on atrial sodium current I(Na) and its tachycardia-induced remodeling were studied in a rabbit model.

METHODS

9 groups with 4 animals were examined. Atrial pacemaker leads were implanted in all animals. No rapid atrial pacing (600/min) was performed in the control group but for 24 or 120 hours in the respective pacing groups. Instrumentation and pacing did not differ from the respective drug groups but an additional treatment with dexamethasone or atorvastatin (7 days) was performed.

RESULTS

Rapid atrial pacing (RAP, 600/min) reduced I(Na) after 24 hours (≈ -50%) with no further reduction after 120 hours. DT reduced I(Na) (≈ -20%), current densities in consecutively tachypaced animals did not differ from those in untreated animals. AT reduced INa similar as RAP, subsequent RAP did not further diminish I(Na).

CONCLUSIONS

Impact of corticosteroids and statins on INa and its tachycardia-induced alterations also contribute to the mode of action of these substances in upstream treatment of atrial fibrillation.

Effects of aldosterone and mineralocorticoid receptor antagonism on cardiac ion channels in the view of upstream therapy of atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia in man. Over the past years, importance of the renin-angiotensin-aldosterone system in AF pathophysiology has been recognized. Lately, the role of aldosterone in AF pathophysiology and mineralocorticoid receptor (MR) antagonism in "upstream" AF treatment is discussed with special regards concerning the effects on AF-induced structural remodeling. However, there is more and more evidence that MR antagonism also influences atrial electrophysiology and, respectively, AF-induced electrical remodeling, whereas the molecular mechanisms are almost unknown. The aim of this mini-review is to give an overview about the role of aldosterone in AF pathophysiology in principle and to summarize current available data concerning affection of cardiac ion channels by aldosterone and MR antagonism. Finally, as modulation of oxidative stress is discussed as one main therapy principle of "upstream" treatment of AF, potential mechanisms how modulation of oxidative stress by aldosterone and accordingly MR antagonism might alter atrial ion currents are delineated. Summarized, publications concerning potential mechanisms of aldosterone- and MR antagonism-modulated cardiac ion channels in various experimental settings are almost exclusively limited to the ventricular level and, partly, they are also contradictorily. Translation of these data to the atria is problematic because atrial and ventricular electrophysiology exhibit remarkable differences. It can be concluded that further research on the "atrial level" is needed in order to clarify the potential impact of the affection of atrial ion channels by aldosterone and accordingly MR antagonism in "upstream" therapy of AF.

Genetic Polymorphisms as Risk Stratification Tool in Primary Preventive ICD Therapy

More and more implantable cardioverter-defibrillators (ICDs) are implanted as primary prevention of sudden cardiac death (SCD). However, major problem in practice is to identify high-risk patients for SCD. Different methods for noninvasive risk stratification do not have a sufficient positive or negative predictive value. Since current approaches lead to implantation of ICDs in a large number of patients who will never suffer an arrhythmic event and simultaneously patients still die of SCD who currently did not seem eligible for primary preventive ICD implantation, there is a need for additional tools for risk stratification. Epidemiological studies point to a hereditary risk of SCD. Different susceptibility of each person concerning arrhythmogenic events might be explained by genetic polymorphisms. By obtaining an individual “pattern” of polymorphisms of genes encoding for proteins which are important in arrhythmogenesis in one patient, risk stratification in primary prevention of SCD might by improved.

Influence of dexamethasone on atrial ion currents and their early ionic tachycardia-induced electrical remodeling in rabbits

BACKGROUND

Certain evidence points to a role of inflammation in AF pathophysiology. Thus, antiinflammatory treatment of AF is discussed. Effects of a dexamethasone treatment (7 days) on atrial ion currents (I(Ca,L), I(to), I(sus)) and their tachycardia-induced remodeling were studied in a rabbit model.

METHODS

6 groups of 4 animals each were built. Rapid atrial pacing (600 min) was performed for 24 and 120 hours with/ without dexamethasone treatment. Ion currents were measured using whole cell patch clamp method.

RESULTS

Rapid atrial pacing reduced (I(Ca,L), I(to) was decreased after 24 hours but almost returned to control values after 120 hours. When dexamethasone-treated animals also underwent atrial tachypacing, pacing-induced reduction of I(Ca,L) was still observed after 24 hours and was even augmented after 120 hours compared to untreated but tachypaced animals. I(to) was not influenced by dexamethasone alone. In dexamethasone-treated animals, reduction of I(to) was not observed after 24 hours but occurred after 120 hours of atrial tachypacing. I(sus) was neither influenced by rapid atrial pacing nor by dexamethasone. Biophysical properties of all currents were affected neither by rapid atrial pacing nor by dexamethasone.

CONCLUSION

Dexamethasone influenced tachycardia-induced alterations of atrial I(to). Our experiments give evidence that - amongst other anti-inflammatory action - impact of dexamethasone on ion currents and their tachycardia-induced alterations might also play a role in treatment/prevention of AF with steroids.

Effects of selective mineralocorticoid receptor antagonism on atrial ion currents and early ionic tachycardia-induced electrical remodelling in rabbits

Over the past years, the importance of the renin-angiotensin-aldosterone system in atrial fibrillation (AF) pathophysiology has been recognised. Lately, the role of aldosterone in AF pathophysiology and mineralocorticoid receptor (MR) antagonism in "upstream" AF treatment is discussed. Hypothesising that selective MR antagonism might also influence atrial ion currents (L-type calcium current [I (Ca,L)], transient outward potassium current [I (to)], sustained outward potassium current [I (sus)]) and their tachycardia-induced remodelling, the effects of an eplerenone treatment were studied in a rabbit model. Six groups each with four animals were built. Animals of the control group received atrial pacing leads, but in contrast to the pacing groups, no atrial tachypacing (600 per minute for 24 and 120 h immediately before heart removal) was applied. Animals of the eplerenone groups were instrumented/paced as the corresponding control/pacing groups, but were additionally treated with eplerenone (7 days before heart removal). Atrial tachypacing was associated with a reduction of I (Ca,L). I (to) was decreased after 24 h of tachypacing, but returned to control values after 120 h. In the absence of rapid atrial pacing, MR antagonism reduced I (Ca,L) to a similar extent as 120 h of tachypacing alone. Based on this lower "take-off level", I (Ca,L) was not further decreased by high-rate pacing. I (to) and its expected tachycardia-induced alterations were not influenced by MR antagonism. In our experiments, selective MR antagonism influenced atrial I (Ca,L) and its tachycardia-induced alterations. As changes of I (Ca,L) are closely linked with atrial calcium signalling, the relevance of these alterations in AF pathophysiology and, accordingly, AF treatment is likely and has to be further evaluated.

[Atrial fibrillation - Links between principles of pathophysiology and treatment]

Atrial fibrillation is the most common supraventricular arrhythmia in humans, basic and clinical sciences are still developing. This present review aims to inform non-cardiologists respectively non-electrophysiologists about the most important pathophysiological concepts and their influence on therapeutical principles of atrial fibrillation. Moe's and Allessie's "multiple wavelet" theory is introduced as well as Haissaguerre's concept of ectopic triggering of paroxysmal atrial fibrillation and the most important aspects of atrial remodeling ("atrial fibrillation begets atrial fibrillation" according to Wijffels) during persistence of atrial fibrillation. Impact of these pathophysiological concepts is discussed within the context of medicamentous, surgical and interventional therapy. Concomitantly, limitations of these therapies due to pathophysiological considerations are delineated.

Catheter ablation of atrial fibrillation using the Navx-/Ensite-system and a CT-/MRI-guided approach

BACKGROUND

Catheter ablation has become the first line of therapy in patients with symptomatic, recurrent, drug refractory atrial fibrillation. However, catheter ablation of atrial fibrillation is still a challenge. This is partially due to the high degree of variability with regard to the individual anatomy. Nevertheless, 3D imaging systems (CT, MRI) provide detailed information about the individual left atrial and pulmonary vein morphology. A 3D CT or MRI reconstruction of the left atrium can be displayed in the Navx-/Ensite-system in a synchronised way during the ablation procedure, thereby facilitating the intervention. This study summarizes our preliminary experience with different strategies of AF ablation using the Navx-/Ensite-system and a CT-/MRI-guided approach.

METHODS

In a total of 41 patients, cardiac MRI (n = 7) or multi-detector spiral computed tomography (n = 34) was performed prior to an ablation procedure. Catheter ablation was performed for paroxysmal atrial fibrillation in 31 patients and for persistent atrial fibrillation in 10 patients. A 3D MRI or high resolution spiral CT data acquisition was performed and a surface rendered model of the LA was created. This model was displayed in the Navx-/Ensite-system throughout the ablation procedure.

RESULTS

Catheter ablation was performed using the Navx-system (n = 38) or the Ensite-system (n = 3). Three strategies were used depending on the type of atrial fibrillation: segmental isolation of the pulmonary veins (facilitated by a 3D real-time visualization of the ablation catheter and a circumferential mapping catheter; group A: 20 patients), linear lesions (group C: 3 patients) and a combined approach (group B; 18 patients). The CT-/MRI-models provided an excellent overview over the pulmonary veins and the left atrial appendage. They revealed a high degree of variability with regard to the individual anatomy (e.g. dimensions of the left atrial appendage, pulmonary vein ostia). The CT scans provided a more detailed reconstruction of the left atrial anatomy than the MRI scans (especially in patients who were in atrial fibrillation at the time of the data acquisition). In some patients, the CT-/MRI-models revealed a very small diameter of some pulmonary veins or side branches close to the ostium (e.g. right inferior pulmonary vein). Therefore, no attempt was made to achieve complete pulmonary vein isolation in some patients. In group A, 16/20 (80%) patients had no arrhythmia recurrence [mean follow-up 359 days (SD +/- 317 days)]. Twelve out of eighteen (67%) patients in group B [mean follow-up 452 days (SD +/- 311 days)] and 2/3 (67%) patients in group C did not experience an arrhythmia recurrence [mean follow-up 1,000 days (SD +/- 34 days)]. There were no major complications.

CONCLUSIONS

The information derived from 3D CT- or MRI-reconstructions facilitates AF ablations performed with the Navx-/Ensite-mapping system and enhances the safety of these procedures. Furthermore, the availability of an additional impedance-based 3D real-time visualization of the ablation catheter and the circular mapping catheter placed in the pulmonary veins represents a major advantage of the Navx system.

[Cardiac resynchronization therapy in non-ischemic cardiomyopathy]

Cardiac resynchronization therapy is recommended in patients with advanced heart failure (usually NYHA class III or IV) despite optimal pharmacologic therapy, severe systolic dysfunction (eg, left ventricular ejection fraction < 35 percent) and intraventricular conduction delay or echocardiographic indices of dyssynchrony and wide QRS complex (eg, QRS > or = 120 ms). Viral infection is the most common cause of myocarditis and has been implicated in the development of non-ischemic cardiomyopathy. We report on a patient who developed progressive congestive heart failure caused by non-ischemic cardiomyopathy after liver transplantation and reactivation of the underlying hepatitis C. Due to an insufficient response to optimized pharmacological therapy, the patient was successfully treated using cardiac resynchronization therapy.

Transient outward potassium current in rabbit atrium is depressed after short-time rapid atrial pacing but recovers after a longer pacing period

In rabbit, after short-time rapid atrial pacing (RAP), atrial ion currents are reduced similarly as in human chronic atrial fibrillation (AF). Using the rabbit model, time-course of transient outward potassium current (I(to)) remodeling due to RAP was studied. RAP (600 bpm) was applied via an atrial lead for 0 (control), 24 and 120 h, n = 4 animals/group. Using patch clamp technique in whole-cell mode, current densities and biophysical properties were measured in isolated atrial myocytes. After 24 h of RAP, a reduction of peak I(to) (mean +/- SEM, test potential +50 mV, +37 degrees C) was observed (60.3 +/- 5.4 pA/pF (control, n = 20) vs. 28.0 +/- 2.5 pA/pF (24 h, n = 21)). Inactivation of I(to) was slower after 24 h, other biophysical properties were unaltered. However, I(to) recovered after 120 h: 51.7 +/- 4.5 pA/pF (n = 26, p = n.s. vs. control). Inactivation tended to also recover to initial values but was still different to control. Early I(to) remodeling due to RAP in rabbits seems to be more complex than previously thought: a time course of I(to) remodeling with swayings has to be considered when using the rabbit model of RAP in order to study early remodeling or rather its therapeutic manipulation.

Segmental pulmonary vein ablation: success rates with and without exclusion of areas adjacent to the esophagus

BACKGROUND

Catheter ablation has become the first line of therapy in patients with symptomatic recurrent, drug-refractory atrial fibrillation (AF). The occurrence of an atrioesophageal fistula is a rare but serious complication after AF-ablation procedures. This risk is even present during segmental pulmonary vein (PV) ablation procedures because the esophagus does frequently have a very close anatomical relationship to the right or left PV ostia. The aim of the present study was to analyze whether the exclusion of areas adjacent to the esophagus does have a significant effect on the success rates after segmental pulmonary vein ablation procedures.

METHODS

Forty-three consecutive patients with symptomatic paroxysmal AF were enrolled in this study. In all patients, a segmental PV ablation procedure was performed. The procedures were facilitated by a 3D real-time visualization of the circumferential mapping catheter placed in the pulmonary veins using the NavX system (St. Jude Medical, St. Paul, MN, USA; open irrigated tip ablation catheter; 43 degrees C; 30 W). In 21 patients, a complete ostial PV isolation was attempted regardless of the anatomical relationship between the ablation sites and the esophagus (group A). In the remaining 22 patients, the esophagus was marked by a stomach tube and areas adjacent to the esophagus were excluded from the ablation procedure (group B). After discharge, patients were scheduled for repeated visits at the arrhythmia clinic at 1, 3, and 6 months after the ablation procedure.

RESULTS

The segmental pulmonary vein ablation procedure could be performed as planned in all patients. In group A, all pulmonary veins could be isolated successfully in 14 out of 21 patients (67%). A mean number of 3.7 pulmonary veins (SD +/- 0.5 PVs) were isolated per patient. The main reasons for an incomplete PV isolation were: small diameter of the PVs, side branches close to the ostium, or poorly accessible PV ostia. In group B, all PVs could be isolated successfully in only 12 out of 22 patients (55%; P = 0.54). A mean number of 3.2 PVs (SD +/- 0.9 PVs) were isolated per patient (P = 0.05). This was mostly due to a close anatomical relationship to the esophagus. The ablation strategy had to be modified in 16/22 patients in group B because of a close anatomical relationship between the left (n = 10) or right (n = 6) PV ostia and the esophagus. After 3 months, the percentage of patients free from an AF recurrence was not significantly different between the two groups (90% vs 95%; P = 0.61). After 6 months, there was no significant difference between the success rates either (81% vs 82%; P = 1.0). There were no major complications in both groups.

CONCLUSIONS

The exclusion of areas adjacent to the esophagus results in a moderately higher percentage of incompletely isolated PVs. However, it does not have a significant effect on the AF recurrence rate during short-term and mid-term follow-up.

Effect of verapamil on tachycardia-induced early cellular electrical remodeling in rabbit atrium

We investigated the effects of a 7-day verapamil pretreatment (VPT, 7.5 mg/kg bodyweight subcutaneously every 12 h) on ionic currents and molecular mechanisms underlying tachycardia-induced early electrical remodeling after 24-h rapid atrial pacing (RAP, 600 bpm) in rabbit atrium. Animals were divided into four groups (n = 6 each group): control (not paced, no verapamil), paced only, verapamil only and verapamil and paced, respectively. VPT doubled ICa,L [7.0 +/- 0.7 pA/pF (control) vs 14.2 +/- 0.6 pA/pF (verapamil only)]. RAP reduced ICa,L by 48% to 3.6 +/- 0.7 pA/pF (paced only). RAP did not affect ICa,L in verapamil-treated animals and averaged 15.3 +/- 0.2 pA/pF (paced and verapamil). RAP resulted in a significant decrease of the expression of the alpha1c subunit (-24.7%) and the beta2A subunit (-13.3%), respectively. VPT led to a similar alteration of subunit expression as RAP ["control" vs "verapamil only", decrease of alpha1c subunit (-25.4%), but no significant change in beta2A subunit expression]. However, after VPT, further diminishment of alpha1c and beta2A subunit expression after rapid atrial pacing was absent. ("verapamil" vs "verapamil and paced", n = 6 both groups). RAP decreased Ito [-45%, 51.5 +/- 3.9 pA/pF (control) vs 26.8 +/- 1.5 pA/pF (paced only)] and was not influenceable by VPT. IK1 was neither affected by RAP nor verapamil pretreatment. Downregulation of alpha1c and beta2A subunit expression and the resulting decay of ICa,L current densities were prevented by verapamil. However, these effects are abolished by multiple other adverse effects of verapamil on atrial electrophysiology.

Influence of verapamil on tachycardia-induced alterations of PP1 and PP2A in rabbit atrium

BACKGROUND

Long-term atrial fibrillation changes in many regulatory and structural processes may result in stabilization of the arrhythmia. There is evidence that decreased amplitude of L-type Ca(2+) current - probably a key mechanism of atrial remodelling -resulting from changes in expression of regulatory proteins is at least jointly responsible.

OBJECTIVES

To assess the expressions of protein phosphatases PP1 and PP2A, as well as the effect of verapamil pretreatment (VPT), in the early phases of atrial fibrillation in a rabbit model.

METHODS

FOUR GROUPS, EACH CONSISTING OF SIX ANIMALS, WERE STUDIED: 'not paced, no drug' group; 'paced, no drug' group (rapid atrial pacing [RAP] 600 beats/min for 24 h); 'not paced, verapamil' (NPV) group (duration of VPT was seven days, verapamil 7.5 mg/kg was administered every 12 h); and 'paced, verapamil' (PV) group (pacemaker stimulation after VPT). Protein expression was evaluated by Western blot analysis.

RESULTS

RAP resulted in an augmented (32%) PP1 expression (not paced, no drug group versus paced, no drug group). The increase in PP1 expression was prevented with VPT (NPV group versus PV group). Expression of PP2A was not influenced by RAP. However, VPT led to an increase of PP2A expression (16%) after RAP (NPV group versus PV group).

CONCLUSIONS

Fortified expression of protein phosphatases might be - besides transcriptional downregulation of channel subunits - another important cause of reduced L-type Ca(2+) current after RAP. Blocking L-type Ca(2+) channels with verapamil to prevent tachycardia-induced changes of PP1 expression might be expedient.