[Anticoagulation after heart valve replacement]

In patients after mechanical heart valve replacement anticoagulation is required for the prevention of thrombotic and thromboembolic events. In this setting oral anticoagulation can only be performed with vitamin K antagonists (VKA), while currently all available non-vitamin K dependent oral anticoagulants (NOAC) are contraindicated in patients with mechanical heart valve replacement. This review deals with anticoagulation in patients with mechanical heart valve replacement as well as coagulation inhibition after bioprosthetic or percutaneous valve replacement. In addition, recommendations are given for antithrombotic medication in patients with mechanical heart valve replacement in various clinical scenarios.

Procedure related complications following implantation of cardiac resynchronization therapy (CRT) and implantable cardioverter-defibrillator (ICD) devices - Insights from the German DEVICE registry

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Stiftung Institut für Herzinfarktforschung

Background

The number of patients receiving cardiac resynchronization therapy (CRT) and implantable cardioverter-defibrillator (ICD) devices has been increasing in the last decades. Both CRT and ICD play an essential role in modern heart failure therapy. However, the implantation procedure might be ensued by serious complications. Therefore, knowledge about the prevalence of complications and identification of risk factors are key to improve patient care.

Methods

Between 2007-2014 the German DEVICE registry enrolled patients from 50 German centers undergoing ICD or CRT implantation. Patient characteristics, data on procedural outcome, adverse events and mortality during index hospitalization and follow-up at 1 year from discharge, were recorded. Patients who suffered from perioperative complications during or shortly after device implantation were identified for comparative analysis with patients without complications.

Results

Out of 4170 patients enrolled, 119 (2.9%) suffered from procedure related complications. The proportion of female patients suffering from perioperative complications was higher with 29.4%, compared to 18.5% of female patients without complications (p=0.003). There were neither any differences in age (66.3±13.6 vs. 65.4±12.5 years; p=0.13), nor in cardiac or non-cardiac comorbidities and in the indications for device implantation between groups. There was a trend towards a higher rate of complications with procedures on pre-existing devices (24,8 vs. 18.1%; p=0.064), than observed with de-novo implantations (75.2 vs. 81.9%; p=0.064). CRT implantations were more frequent among patients who suffered from complications (46.2 vs. 28.9%; p<0.001), compared to the group without complications, in which the proportion of ICD implantations was much more frequent (53.8 vs. 71.1%; p<0.001). The most frequent complication overall was pocket hematoma (55.1%), followed by pneumothorax (30.3%), pericardial effusion/tamponade (12.7%) and haemothorax (4.2%). The median hospital stay was significantly longer for patients with complications (7 [5; 11] vs. 3 [2; 5] days; p<0.001)). There was no difference in all-cause in-hospital mortality between respective groups. Median follow-up was 455 [398; 551] vs. 462 [391; 569] days (p=0.82) with no differences in all-cause mortality (6.5 vs. 6.9%; p=0.88), device-associated complications (12.6 vs. 8.5%; p=0.18) or rehospitalizations (37.9 vs. 32.2%; p=0.26) after 1-year follow-up.

Conclusion

The overall procedure-related complication rate following CRT or ICD implantation is low (2.9%). Among patients with complications female gender and patients receiving CRT devices were more prevalent. Perioperative device complications neither seem to translate into increased in-hospital mortality, nor in increased rates of further device-associated complications, rehospitalizations or death after 1-year follow-up.

Optimal antithrombotic regimen in patients with cardiogenic shock on ImpellaTM mechanical support: less might be more

Background

Bleeding and ischemic complications are the main cause of morbidity and mortality in critically ill cardiogenic shock patients, supported by short-term percutaneous mechanical circulatory support (pMCS) devices. Hence, finding the optimal antithrombotic regimen is challenging. Bleeding not only occurs because of heparin and antiplatelet therapy (both required in the prevention of pump and acute stent thrombosis) but also because of device- and disease related coagulopathy. To prevent clotting-related device failure, most centers target full therapeutic heparin anticoagulation levels in left ventricular (LV) Impella™ supported patients in analogy with Veno-Arterial Extracorporeal Membrane Oxygenation. We aimed to investigate the safety (related to bleeding and thrombotic complications) of targeting low-dose versus therapeutic heparin levels in left Impella™-supported cardiogenic shock patients on dual antiplatelet therapy (DAPT).

Methods

In this hypothesis generating pilot study, we investigated 114 patients supported for at least two days by LV Impella™ mechanical support due to cardiogenic shock at three tertiary ICUs, highly specialized in mechanical support. Low-dose heparin (aPTT 40–60s or anti-Xa 0.2–0.3) was compared to standard of care (aPTT 60–80s or anti-Xa 0.3–0.5). Major adverse cardio- and cerebrovascular events (MACCE; composite of death, myocardial infarction, stroke/transient ischemic attack) and BARC bleeding (bleeding academic research consortium classification) during 30 day follow-up were assessed. Inverse probability of treatment weighting (IPTW) analysis was calculated with age, gender, arterial hypertension, diabetes mellitus, smoking, chronic kidney disease, previous stroke, previous myocardial infarction, previous coronary arterial bypass grafting, hypercholesterolemia and DAPT as matching variables. COX regression analysis was conducted to test for robustness.

Results

IPTW revealed 52 patients in the low-dose heparin group and 62 patients in the therapeutic group. Mean age of patients after IPTW was 62±16 years in the intermediate and 62±13 years in the therapeutic group (p=0.99). 25% and 42.2% were male (p=0.92). Overall bleeding events and major (BARC3b) bleeding events were higher in the therapeutic heparin group (overall bleeding: Hazard ratio [HR]=2.58, 95% confidence interval [CI] 1.2–5.5; p=0.015; BARC 3b: HR=4.4, 95% CI 1.4–13.6, p=0.009). Minor bleeding (BARC3a) as well as MACCE and its single components (ischemic events) did not differ between both groups. These findings were robust in the COX regression analysis.

Conclusion

In this pilot analysis, low-dose heparin in 114 LV Impella™ cardiogenic shock patients was associated with less bleeding without increased ischemic events, adjusted for DAPT. Reducing the target heparin levels in critically ill patients supported by LV Impella™ might improve the outcome of this precarious group. These findings need to be validated in randomized clinical trials.

Funding Acknowledgement

Type of funding source: None

Updated Survey on Interventional Electrophysiology: 5-Year Follow-Up of Infrastructure, Procedures, and Training Positions in Germany

OBJECTIVES

This study provides an update and comparison to a 2010 nationwide survey on cardiac electrophysiology (EP), types and numbers of interventional electrophysiological procedures, and training opportunities in 2015.

BACKGROUND

In 2010, German cardiology centers performing interventional EP were identified and contacted to provide a survey on cardiac EP.

METHODS

German cardiology centers performing interventional EP in 2015 were identified from quality reports and contacted to repeat the 2010 questionnaire.

RESULTS

A majority of 131 centers (57%) responded. EP (ablation procedures and device therapy) was mainly part of a cardiology department (89%) and only independent (with its own budget) in 11%. The proportion of female physicians in EP training increased from 26% in 2010 to 38% in 2015. In total, 49,356 catheter ablations (i.e., 81% of reported ablations in 2015) were performed by the responding centers, resulting in a 44% increase compared with 2010 (the median number increased from 180 to 297 per center). Atrial fibrillation (AF) was the most common arrhythmia interventionally treated (47%). At 66% of the centers, (at least) 2 physicians were present during most catheter ablations. A minimum of 50 (75) AF ablations were performed at 80% (70%) of the centers. Pulmonary vein isolation with radiofrequency point-by-point ablation (62%) and cryoablation (33%) were the preferred ablation strategies. About one-third of centers reported surgical AF ablations, with 11 centers (8%) performing stand-alone surgical AF ablations. Only one-third of the responding 131 centers fulfilled all requirements for training center accreditation.

CONCLUSIONS

Comparing 2010 with 2015, an increasing number of EP centers and procedures in Germany are registered. In 2015, almost every second ablation was for therapy for AF. Thus, an increasing demand for catheter ablation is likely, but training opportunities are still limited, and most centers do not fulfil recommended requirements for ablation centers.

[AV-reentrant tachycardia and Wolff-Parkinson-White syndrome : Diagnosis and treatment]

The AV-reentrant tachycardia (AVRT) is a supraventricular tachycardia with an incidence of 1-3/1000. The pathophysiological basis is an accessory atrioventricular pathway (AP). Patients with AVRT typically present with palpitations, an on-off characteristic, anxiety, dyspnea, and polyuria. This type of tachycardia may often be terminated by vagal maneuvers. Although the clinical presentation of AVRT is quite similar to AV-nodal reentrant tachycardias, the correct diagnosis is often facilitated by analyzing a standard 12-lead ECG at normal heart rate showing ventricular preexcitation. Curative catheter ablation of the AP represents the therapy of choice in symptomatic patients. This article is the fourth part of a series written to improve the professional education of young electrophysiologists. It explains pathophysiology, symptoms, and electrophysiological findings of an invasive EP study. It focusses on mapping and ablation of accessory pathways.

[Implantable loop recorders of the Reveal family (Medtronic)]

This review explains the implantable loop recorders Medtronic Reveal XT and Medtronic Reveal LINQ. Technical specifications of the two devices are described in great detail. Additional tips for implantation as well as device programming are given including specific considerations of follow-up.

[AV nodal reentrant tachycardia. Diagnosis and therapy]

The AV nodal reentrant tachycardia (AVNRT) is one of the most common arrhythmias encountered in clinical practice. It is characterized by a constant heart rate and an on/off phenomenon. The clinical symptoms may include palpitations, anxiety, polyuria, and dyspnea. Typically, tachycardia may be disrupted by vagal maneuvers in many patients. First-line treatment of symptomatic AVNRT is radiofrequency ablation. The present article deals with the characteristics, differential diagnosis and treatment of AVNRT in the EP lab. It is the second part of a series of manuscripts which may facilitate further education in the specific field of electrophysiology.

Safety of symptom-limited exercise testing in a big cohort of a modern ICD population

BACKGROUND

Exercise may predispose to ventricular arrhythmias especially in patients with congestive heart failure. As therapy with implanted cardioverter-defibrillators (ICDs) has become standard medical care, there is an emerging number of exercise tests that need to be performed in patients with ICDs. In contrast, little is known about the safety of symptom-limited exercise testing in these patients.

METHODS AND RESULTS

400 ICD patients performed symptom-limited exercise treadmill testing. 200 patients performed a ramp protocol with an initial workload of 0 W increased by 15 W every minute. Another 200 ICD patients did a slightly modified ramp protocol with again an initial workload of 0 W but with an increased capacity of 15 W every 2 min. The study population consists mainly of patients with ischemic (63%) and non-ischemic (34%) heart disease. Atrial fibrillation was present in 16% of the subjects. The mean ejection fraction was 28 ± 8, and 78% of the patients had an ejection fraction below 30%. In this cohort of patients, no sustained ventricular arrhythmias and no deaths occurred during or after exercise testing. No inappropriate shock delivery was observed. The modified ramp protocol resulted in a prolonged exercise time with equal exercise capacity but does not result in an enhanced susceptibility for ventricular arrhythmias.

CONCLUSIONS

Symptom-limited exercise treadmill testing in heart failure patients with ICDs is a safe procedure. The use of a ramp protocol is sufficient in terms of safety and is easy to perform in general practice. The exercise duration in heart failure patients with ICDs does not predict serious adverse events.

[How to approach the patient with supraventricular tachycardia in the EP lab: A systematic overview]

The term supraventricular tachycardia (SVT) summarizes those tachycardias involving the atrial myocardium along with the atrioventricular (AV) node. The prevalence is about 2.25 per 1000 (without atrial fibrillation and atrial flutter) and, therefore, SVT represents one of the most common group of arrhythmias besides atrial fibrillation encountered in the emergency department especially since they tend to recur until definite therapy. The clinical symptoms may include palpitations, anxiety, presyncope, angina, and dyspnea. Pharmacological therapy of these arrhythmias often fails. The present article deals with the differential diagnosis of SVT and also introduces a series of manuscripts that provide detailed insight into the differential diagnosis and treatment of these arrhythmias.

Bacteriology of aspiration pneumonia in patients with acute coma

Loss of protective airway reflexes in patients with acute coma puts these patients at risk of aspiration pneumonia complicating the course of the primary disease. Available data vary considerably with regard to bacteriology, role of anaerobic bacteria, and antibiotic treatment. Our objective was to research the bacteriology of aspiration pneumonia in acute coma patients who were not pre-treated with antibiotics or hospitalized within 30 days prior to the event. We prospectively analyzed 127 patient records from adult patients admitted, intubated and ventilated to a tertiary medical intensive care unit with acute coma. Bacteriology and antibiotic resistance testing from tracheal aspirate sampled within 24 h after admission, blood cultures, ICU scores (APACHE II, SOFA), hematology, and clinical chemistry were assessed. Patients were followed up until death or hospital discharge. The majority of patients with acute coma suffered from acute cardiovascular disorders, predominantly myocardial infarction, followed by poisonings, and coma of unknown cause. In a majority of our patients, microaspiration resulted in overt infection. Most frequently S. aureus, H. influenzae, and S. pneumoniae were isolated. Anaerobic bacteria (Bacteroides spec., Fusobacteria, Prevotella spec.) were isolated from tracheal aspirate in a minority of patients, and predominantly as part of a mixed infection. Antibiotic monotherapy with a 2nd generation cephalosporin, or a 3rd generation gyrase inhibitor, was most effective in our patients regardless of the presence of anaerobic bacteria.

A phase I study of two dosing schedules of volasertib (BI 6727), an intravenous polo-like kinase inhibitor, in patients with advanced solid malignancies

BACKGROUND

Polo-like kinase 1 (Plk1) has an important role in mitosis. Volasertib (BI 6727), a potent and selective cell cycle kinase inhibitor, induces mitotic arrest and apoptosis by targeting Plk; this phase I study sought to determine its maximum tolerated dose (MTD) in Asian patients with advanced solid tumours.

METHODS

Patients were enrolled simultaneously into two 3-week schedules of volasertib: a 2-h infusion on day 1 (schedule A) or days 1 and 8 (schedule B). Dose escalation followed a 3+3 design. The MTD was determined based on dose-limiting toxicities (DLT) in the first treatment course.

RESULTS

Among 59 treated patients, the most common first course DLTs were reversible thrombocytopenia, neutropenia and febrile neutropenia; MTDs were 300 mg for schedule A and 150 mg for schedule B. Volasertib exhibited multi-exponential pharmacokinetics (PK), a long terminal half-life of ∼135 h, a large volume of distribution (>3000 l), and a moderate clearance. Partial responses were observed in two pre-treated patients (ureteral cancer; melanoma). Volasertib was generally well tolerated, with an adverse event profile consistent with its antimitotic mode of action and a favourable PK profile.

CONCLUSIONS

These data support further development of volasertib and a harmonised dosing for Asian and Caucasian patients.

A survey of German centres performing invasive electrophysiology: structure, procedures, and training positions

AIMS

To provide a nationwide survey (and reference for the future) on cardiac electrophysiologists, types and numbers of invasive electrophysiological procedures, and training opportunities in 2010.

METHODS AND RESULTS

German cardiology centres performing invasive electrophysiology were identified from quality reports and contacted to fill a questionnaire. A majority of 122 centres (65%) responded. Electrophysiology (ablation procedures and device therapy) was mainly part of a cardiology department (82%), and only in 9% independent (own budget). In only 58% of the centres, (at least) two physicians were present during catheter ablations. Although in 2010, women represented 59.4% of physicians <35 years old, only 26% of physicians in electrophysiology training were female. In total, 33 420 catheter ablations were performed with a median number of 180 per centre. Atrial fibrillation (AF) was the most common arrhythmia invasively treated (35%). At least 50 AF ablations were performed in 53% of the centres. Of the centres performing AF ablations, consecutive left atrial arrhythmias were treated by catheter ablation only in 75%, and only 44% had in-house surgical backup. Only one-fourth of the 122 centres fulfilled all requirements for training centre accreditation according to the European Heart Rhythm Association and the German Cardiac Society.

CONCLUSION

The results indicate a high number of electrophysiology centres and procedures in Germany. Atrial fibrillation was the most common arrhythmia invasively treated. An increasing demand for catheter ablation is likely, but training opportunities are limited. Women are clearly underrepresented. A co-operation of higher and lower volume electrophysiology centres may be necessary for training purposes.

Occurrence of phrenic nerve stimulation in cardiac resynchronization therapy patients: the role of left ventricular lead type and placement site

AIMS

Unwanted phrenic nerve stimulation (PNS) has been reported in ∼1 in 4 patients undergoing left ventricular (LV) pacing. The occurrence of PNS over mid-term follow-up and the significance of PNS are less certain.

METHODS AND RESULTS

Data from 1307 patients enrolled in pre-market studies of LV leads manufactured by Medtronic (models 4193 and 4195 unipolar, 4194, 4196, 4296, and 4396 bipolar) were pooled. Left ventricular lead location was recorded at implant using a common classification scheme. Phrenic nerve stimulation symptoms were either spontaneously reported or identified at scheduled follow-up visits. A PNS-related complication was defined as PNS resulting in invasive intervention or the termination of LV pacing. Average follow-up was 14.9 months (range 0.0-46.6). Phrenic nerve stimulation symptoms occurred in 169 patients (12.9%). Phrenic nerve stimulation-related complications occurred in 21 of 1307 patients (1.6%); 16 of 738 (2.2%) in the unipolar lead studies, and 5 of 569 (0.9%) in the bipolar lead studies (P = 0.08). Phrenic nerve stimulation was more frequent at middle-lateral/posterior, and apical LV sites (139/1010) vs. basal-posterior/lateral/anterior, and middle-anterior sites (20/297; P= 0.01). As compared with an anterior LV lead position, a lateral LV pacing site was associated with over a four-fold higher risk of PNS (P= 0.005) and an apical LV pacing site was associated with over six-fold higher risk of PNS (P= 0.001).

CONCLUSION

Phrenic nerve stimulation occurred in 13% of patients undergoing LV lead placement and was more common at mid-lateral/posterior, and LV apical sites. Most cases (123/139; 88%) of PNS were mitigated via electrical reprogramming, without the need for invasive intervention.

Measurement of the 60Fe(n, gamma)61Fe Cross Section at Stellar Temperatures

Observations of galactic gamma-ray activity have challenged the current understanding of nucleosynthesis in massive stars. Recent measurements of (60)Fe abundances relative to ;{26}Al;{g} have underscored the need for accurate nuclear information concerning the stellar production of (60)Fe. In light of this motivation, a first measurement of the stellar (60)Fe(n, gamma)(61)Fe cross section, the predominant destruction mechanism of (60)Fe, has been performed by activation at the Karlsruhe Van de Graaff accelerator. Results show a Maxwellian averaged cross section at kT = 25 keV of 9.9 +/-_{1.4(stat)};{2.8(syst)}mbarn, a significant reduction in uncertainty with respect to existing theoretical discrepancies. This result will serve to significantly constrain models of (60)Fe nucleosynthesis in massive stars.

There is no transmural heterogeneity in an index of action potential duration in the canine left ventricle

BACKGROUND

Transmural heterogeneity in ventricular repolarization demonstrated in vitro has been difficult to confirm in vivo. Whether this discrepancy reflects a physiological phenomenon or a methodological problem remains a vivid matter of debate despite a plethora of experimental work. Therefore, we have measured the relevant electrophysiological parameters first in vivo and repeated these in the same heart and at identical sites in vitro. Methodological issues were tackled by using both unipolar and bipolar recordings. Physiological issues were explored by measuring both local and functional electrophysiological parameters.

METHODS

In 10 healthy dogs, 2 high-resolution needle electrodes were inserted into the left ventricle. Effective refractory periods (ERP) as well as activation recovery intervals (ARI) were determined at each electrode along both needles at basic cycle lengths (BCL) of 850 and 300 ms, respectively. After excision of the heart, ERP and ARI measurements were repeated in the arterially perfused wedge preparations.

RESULTS

First, we observed that ERPs and ARIs were significantly shorter in vivo than in vitro. Mean ERPs and ARIs of all muscle layers were relatively uniform throughout the ventricular wall in vivo. The transition from the in vivo to the in vitro preparation was associated with a significant albeit small increase of mean ARIs in the subendocardium, whereas interlayer differences in mean ERPs did not reach statistical significance as in vivo.

CONCLUSION

In the intact canine left ventricular wall, a more or less homogeneous distribution in transmural ERP and ARI is present.

"Home monitoring" for early detection of implantable cardioverter-defibrillator failure: a single-center prospective observational study

BACKGROUND

Telemedical ICD monitoring has the potential to enhance patient safety. The "home-monitoring" (HM) feature transmits selected device-related data to a service-center via mobile phone network. In case of a potential emergency situation, event reports are generated automatically. This prospective observational study was designed to test whether HM is effective and reliable in early detection of device failure.

METHODS

Consecutive patients receiving ICD, CRT-D or CRT pacemaker systems with HM feature were included. Regular follow-up visits were performed 1, 3, 6, 9 and 12 months after implantation in the first year, and every 6 months thereafter. All event reports transmitted by HM were analyzed and severe device-related events (serious lead or device dysfunction, hospitalization, death) were documented including timing, type and mode of detection.

RESULTS

Sixty-nine patients were included and followed for 18 +/- 9 months. A total of 206 event reports were transmitted, prompted by VF/VT-episodes (n = 193), ineffective ICD shocks (n = 7), abnormal pacing impedance (n = 4) or battery depletion (n = 2). 8 SAEs were observed (RV lead fracture; n = 5, connector defect; n = 1, sensing defect, n = 1, RV lead dislodgement, n = 1). There was no device-related death. 6 out of 8 SAEs were discovered by HM (sensitivity, 75%). Without HM, these events would have been detected with a theoretical delay of 1.9 +/- 0.5 months in the first year (3 monthly FU) and 4.9 +/- 0.5 months in the following years (6 monthly FU).

CONCLUSIONS

This pilot study demonstrates that HM enables early detection of ICD failure and appears to enhance patient safety.

Elevated B-type natriuretic peptide levels in patients with nonischemic cardiomyopathy predict occurrence of arrhythmic events

BACKGROUND

Patients with nonischemic cardiomyopathy (DCM) are at high risk for sudden cardiac death (SCD). However, the predictive value of prophylactic implantation of implantable cardioverter defibrillators (ICD) in this patient cohort is yet unclear.

METHODS AND RESULTS

Whether NT pro BNP levels and/or reproducible non sustained ventricular tachycardias (NSVTs) are predictive for SCD was prospectively tested in 30 patients with DCM and LVEF </= 40%. All patients received Holter-recordings (HR) on three consecutive days and baseline NT-pro BNP levels were determined. Patients were followed for occurrence of ventricular tachyarrhythmias or unexplained syncope. A great degree of variability was found regarding the occurrence of NSVTs (10% had NSVTs in two consecutive HR, 10% in three consecutive HR, 30% in one HR and 50% had no NSVTs). Patients with NSVTs in more than one HR had significantly higher NT-pro BNP levels (first quartile: 715 pg/ml, median 2,176 pg/ml, third quartile 5,755 pg/ml vs. first quartile 273 pg/ml, median 566 pg/ml, third quartile 1,350 pg/ml, P = 0.0388). During a mean follow-up of 21.6 +/- 1.2 months patients with an arrhythmic event had significantly higher NT-pro BNP levels than patients without event (first quartile: 1,002 pg/ml, median 4,075 pg/ml, third quartile 7,777 pg/ml vs. first quartile 173 pg/ml, median 267 pg/ml, third quartile 1,220 pg/ml, P = 0.0135). NT-pro BNP levels of 2,259 pg/ml were identified as optimal cut-off value for the prediction of arrhythmic events (P = 0.0313). In contrast reproducible NSVTs were not predictive for arrhythmic events (P = 0.0960).

CONCLUSION

The present study demonstrates that in patients with DCM the value of reproducible NSVTs in predicting arrhythmic events is low. In contrast raised NT-pro BNP levels significantly correlated with occurrence of symptomatic ventricular arrhythmias. Larger prospective trials are required to confirm these results.

Prophylactic implantation of cardioverter-defibrillator in patients with severe cardiac amyloidosis and high risk for sudden cardiac death

BACKGROUND

Cardiac light-chain amyloidosis carries a high risk for death predominantly from progressive cardiomyopathy or sudden death (SCD). Independent risk factors for SCD are syncope and complex nonsustained ventricular arrhythmias.

OBJECTIVE

The purpose of this study was to test whether prophylactic placement of an implantable cardioverter-defibrillator (ICD) reduces SCD in patients with cardiac amyloidosis.

METHODS

Nineteen patients with histologically proven cardiac amyloidosis and a history of syncope and/or ventricular extra beats (Lown grade IVa or higher) received an ICD.

RESULTS

During a mean follow-up of 811 +/- 151 days, two patients with sustained ventricular tachyarrhythmias were successfully treated by the ICD. Two patients underwent heart transplantation, and seven patients died due to electromechanical dissociation (n = 6) or glioblastoma (n = 1). Nonsurvivors more often showed progression of left ventricular wall thickness, low-voltage pattern, ventricular arrhythmias (Lown grade IVa or higher), and higher N-terminal pro-brain natriuretic peptide levels than did survivors. Bradycardias requiring ventricular pacing (VVI 40/min <1%, DDD 60/min 6% +/- 1%) occurred only rarely.

CONCLUSION

Patients with cardiac amyloidosis predominantly die as a result of electromechanical dissociation and other diagnoses not amenable to ICD therapy. Selected patients with cardiac amyloidosis may benefit from ICD placement. Better predictors of arrhythmia-associated SCD and randomized trials are required to elucidate the impact of ICD placement in high-risk patients with cardiac amyloidosis.

Effects of protein kinase C activation on cardiac repolarization and arrhythmogenesis in Langendorff-perfused rabbit hearts

AIMS

Cardiac arrhythmias are still a major cause of mortality in western countries. Currently available antiarrhythmic drugs are limited by a low efficacy and proarrhythmic effects. The role of the protein kinase C (PKC) signalling pathway in arrhythmogenesis is still unclear. The goal of the present study was to test the effects of PKC stimulation on whole heart electrophysiology and its pro-/antiarrhythmic activity.

METHODS AND RESULTS

Left ventricular (LV) action potential duration (APD 90%) was determined in 27 Langendorff-perfused rabbit hearts, using Tyrode solution plus the PKC agonist phorbol-12-myristate-13-acetate (PMA; 100 nM) alone (nine rabbits), Verapamil alone (n = 6), or PMA in combination with Verapamil (0.25 mg/L, six rabbits), or bisindolylmaleimide (0.5 microM, n = 6). Intermittent programmed extra-stimulation was performed to induce ventricular arrhythmias. Administration of PMA alone led to a significant shortening of repolarization (APD 90%, 157 +/- 8 vs. 128 +/- 5 ms, P<0.05). Non-sustained ventricular fibrillation (VF) could be induced in seven out of nine animals. After perfusion of Verapamil (156 +/- 6 vs. 169 +/- 4 ms, P>0.05) or bisindolylmaleimide, a selective inhibitor of PKC (136 +/- 4 vs. 146 +/- 4 ms, P>0.05), PMA-induced shortening of repolarization could be inhibited, and induction of VF failed. Verapamil alone did not affect APD and VF could not be induced.

CONCLUSIONS

Activation of PKC facilitates induction of VF, which is most likely due to a shortening of repolarization and a prominent calcium influx. These findings demonstrate involvement of the PKC-signalling pathway in arrhythmogenesis.

Indications for predismissal testing with arrhythmia-induction in patients receiving an implantable cardioverter defibrillator

Arrhythmia induction during implantation of cardioverter defibrillators (ICD) is a standard procedure. However, controversy exists regarding the need for routine arrhythmia induction before discharge from hospital (pre-hospital discharge (PHD) test). In order to reduce the number of tests we identified risk factors that predict relevant ICD malfunction.

METHODS AND RESULTS

965 patients receiving a first device implantation (n=724) or device/system replacement (n=241) between 1998 and 2004 were analysed. During implantation 176 (18%) complications (intraoperative undersensing of induced arrhythmias, unsuccessful arrhythmia-therapy or low DFT safety margin) occurred. Frequent (>4 times) intraoperative lead repositioning due to low sensing values was present in 44 patients (5%). 9% of the patients with first ICD implantation, 21% with device replacement and 27% with system replacement developed complications during PHD testing with arrhythmia induction. Intraoperative complications, although corrected during implantation, were independent risk factors for malfunction during PHD testing (p<0.05). Additional predictors for malfunction were intraoperative lead repositioning (>4 times) and a history of both VF and VT (p<0.05). Patients without intraoperative complications rarely developed malfunction during PHD testing (3.7% first device, 6.25% system replacement). Only in patients undergoing device replacement was a higher risk for failure (13%) evident. No risk factors could be identified for these subgroups.

CONCLUSION

Routine arrhythmia induction during PHD is recommended in ICD patients with intraoperative complications, although corrected during implantation, as well as frequent intraoperatives lead repositioning. Patients undergoing device/system replacement uncomplicated implantation are not generally at low risk for device failure.

Role of KATP channels in repetitive induction of ventricular fibrillation

AIM

Patients with sustained ventricular tachyarrhythmias are at high risk for sudden cardiac death. The mechanisms leading to multiple temporally related episodes of ventricular fibrillation (VF) are not yet fully elucidated, and treatment options are limited. We investigated whether K(ATP)-channels could be involved in triggering VF.

METHODS

We determined postarrhythmic changes of monophasic action potentials (MAP) after repetitive induction of VF in 32 Langendorff-perfused rabbit hearts.

RESULTS

Postarrhythmic action potential duration (APD) was significantly shorter compared with baseline (100 +/- 12 ms vs. 140 +/- 8 ms, P < 0.05). With increasing numbers of VF and shortening of recovery intervals between VF episodes (2 min) inducibility of VF increased, and abbreviation of APD became more prominent (90 +/- 5 ms vs. 130 +/- 4 ms, P < 0.05). Pre-treatment with the selective K(ATP) blocking agent HMR 1883 led to a significant increase of postarrhythmic APDs compared with control hearts (100 +/- 12 ms vs. 118 +/- 3 ms, P = 0.0013). Moreover, HMR 1883 significantly reduced inducibility of VF and increased the rate of successful defibrillation.

CONCLUSIONS

Repetitive episodes of VF result in postarrhythmic abbreviation of APDs, a phenomenon thought to be of potential relevance for incessant tachyarrhythmias in patients. Prevention of postarrhythmic MAP-shortening by HMR 1883 might be useful in suppressing VF.

[Efficiency potential in the pacemaker/implantable cardioverter defibrillator outpatient clinic]

The aim of the present study was to elucidate whether the duration of a technical follow-up (FU) of a pacemaker (PM)/implantable cardioverter defibrillator (ICD) has an impact on cost-effectiveness in the outpatient clinic. We determined the time required for a complete FU of devices from three different manufacturers. In 130 patients (70 VVI/DDD-PM, 60 VVI/DDD-ICD) with either a PM (Phylos, Chorum/Talent, Kappa, EnPulse) or an ICD (Belos, Alto or GEM) the time was recorded for a complete FU including determination of lead impedance, sensing and pacing threshold. The time for activation of individual menue buttons was excluded. On the basis of time required for FU, cost-units (CU) were calculated for 2000 FU/year and for a presumed device longevity (PM 7 years, ICD 5 years). For VVI-PM, the duration of FU was almost identical for devices from different manufacturers (105+/-11 s to 125+/-8 s; p=n.s.). However, analysis of DDD-PM revealed marked differences (140+/-25 s vs 282+/-23 s, p<0.05). Time for FU of ICDs varied between 108+/-5 s and 207+/-21 s (p<0.05) in VVI-ICDs and between 129+/-8 ms and 225+/-23 s (p<0.05) in DDD-ICDs. The total savings could be 55 000 CU in VVI- and 53 333 CU in DDD-ICDs. For full automatic DDD-pacemakers (EnPulse) time for FU could be reduced to 58+/-3 s (p<0.05). Differences in FU times were caused by problems with telemetry, delay during booting of the programmer, interrogation at the beginning and at the end of FU and for sensing tests. Improving not only programmers and devices but also test automaticity could significantly increase cost-efficiency in the outpatient clinic.

Regional differences in the dynamics of refractoriness in intact and hypertrophied in situ canine hearts

OBJECTIVES

Functional re-entry is thought to represent the predominant mechanism underlying ventricular arrhythmias. Functional conduction block may be caused by regional dispersion of refractoriness (ERP). Dispersion of ERP may not be evident at baseline, but may occur with sudden changes in heart rate, as ventricular arrhythmias are commonly induced by short-long-short cycles.

METHODS

We examined the dynamics of local ERPs at two left ventricular (LV) sites in dogs with either no structural heart disease or biventricular hypertrophy (BVH). ERPs were determined at each of four bipoles of two adjacent needle electrodes in the LV apex and the lateral wall. The stimulation protocol included two different basic cycle lengths, one or two longer cycles after a train of 6 or 5 shorter cycles, and one shorter cycle after a train of 6 longer cycles.

RESULTS

In normal dogs, a significant apicolateral ERP gradient was only evident with the longer basic cycle length. One shorter cycle was sufficient to dissolve that gradient. One longer cycle was enough to create a regional ERP gradient. Dynamic regional gradients occurred because the apex responded more markedly and more readily to abrupt changes in cycle length. BVH led to an increase in ERP at both LV sites and to an aggravation of regional ERP gradients.

CONCLUSIONS

Dynamic ERP behavior seems to depend on topography and underlying pathology. Abrupt changes in heart rate might induce dynamic refractory gradients between various regions of the normal heart, but also between adjacent regions inhomogenously affected by hypertrophy.