ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices) developed in collaboration with the American Association for Thoracic Surgery and Society of Thoracic Surgeons

The role of speckle tracking strain imaging in cardiac pacing

In recent years, concerns have been raised about possible harmful effects of long-term right ventricular (RV) apical pacing. These detrimental effects may be related to changes in left ventricular (LV) mechanics during RV apical pacing. As a consequence, alternative RV pacing sites have been proposed, and in selected patients an upgrade from RV to biventricular pacing may be considered. Novel two-dimensional (2D) speckle tracking strain imaging allows detailed evaluation of LV mechanics, including LV mechanical dyssynchrony, LV strain and LV torsion. In this review, the role of speckle tracking strain imaging in the evaluation of LV function in patients with RV apical pacing will be reviewed. The effects of RV apical pacing on LV mechanical dyssynchrony, LV strain and LV torsion will be discussed. In addition, the role of speckle tracking strain imaging in the selection of the optimal (alternative) RV pacing site and in the selection of patients who may benefit from an upgrade from RV apical pacing to biventricular pacing will be reviewed.

[Fetal ultrasonography and Doppler in isolated congenital heart block]

Isolated congenital heart block is linked to transplacental passage of maternal anti-SSA/Ro and/or anti-SSB/La antibodies that may be related to a connective tissue disease. Ultrasonography and Doppler are essential to screen fetus at risk. They allow the diagnosis of first- and second-degree blocks which are probably preliminary stages in conducting tissue's injury. In these situations, a maternal treatment by fluorinated steroids can be proposed because of its possible effect on partial blocks. However, these early signs of nodal injury can be lacking: some fetus present a complete heart block without previously detected less advanced block. Moreover, the significance of first-degree block is unclear since it could reverse spontaneously. Other markers of nodal injury would be valuable. In case of complete congenital heart block, ultrasonography is useful to detect congestive heart failure and help the obstetrical management when unfavorable prognostic signs occur.

Use of beta-blockers in patients with an implantable cardioverter defibrillator

BACKGROUND

Implantable cardioverter defibrillators (ICDs) are indicated for both primary and secondary prevention of sudden cardiac arrest. beta-Blockers are also indicated in most patients who have an indication for an ICD; however, their use in this population is not well described. Some clinicians may be unaware of the recommendation for beta-blockers in this population.

OBJECTIVE

To explore beta-blocker use among ICD recipients.

METHODS

Adults who received their first ICD at Duke Hospital between July 1999 and July 2004 for primary or secondary prevention of sudden cardiac arrest were identified. Using hospital data, beta-blocker use was determined at time of discharge, and characteristics of users were compared with those of nonusers. Continued use of beta-blockers after ICD implant was explored in the subset of patients included in the Duke Databank for Cardiovascular Disease (DDCD).

RESULTS

The study cohort comprised 804 patients, 652 (81%) with ICD for secondary prevention of sudden cardiac arrest and 152 (19%) for primary prevention. The median age was 65 years and 75% of the patients were men. A total of 544 (68%) received a beta-blocker at time of ICD implant. There were no substantial changes in the proportion of patients with beta-blocker use from 1999 through 2004, overall or within the primary or secondary prevention groups. However, beta-blocker use was higher in the secondary prevention group than in the primary prevention group (69% vs 60%; p = 0.02). A higher proportion of beta-blocker users versus nonusers had ischemic heart disease (82% vs 68%; p < 0.0001), heart failure (84% vs 71%; p < 0.0001), previous myocardial infraction (51% vs 44%; p = 0.05), and ventricular arrhythmias (82% vs 76%; p = 0.04). Of the 425 patients included in the DDCD, only 241 (57%) were receiving beta-blockers at time of implant and during clinical follow-up.

CONCLUSIONS

Lower than optimal use of beta-blockers suggests the need for new methods of including evidence-based medications in clinical practice, especially for complex patients for whom numerous clinical practice guidelines may apply.

Noninvasive risk stratification after myocardial infarction: rationale, current evidence and the need for definitive trials

Despite advances in therapies for myocardial infarction (MI), death attributed to a cardiac arrest from ventricular tachycardia (VT) or ventricular fibrillation (VF) remains an important problem. The implantable cardioverter defibrillator (ICD) is effective in preventing death from VT/VF, but reliably identifying which post-MI patients would benefit from an ICD remains a major challenge. Beyond the initial post-MI period, the presence of significant left ventricular (LV) dysfunction, alone or in combination with the induction of sustained VT/VF during invasive testing, is the only proven means of selecting patients for a prophylactic ICD. However, these approaches identify only a fraction of those at risk. Furthermore, most patients with significant LV dysfunction after MI have a low, near-term risk of VT/VF. Noninvasive risk stratification tools have been developed to better identify patients likely to benefit from an ICD. To date, none of these tools has been proven useful in this regard. The factors leading to a cardiac arrest are complex, and a single test is unlikely to reliably predict risk. Noninvasive assessment of cardiac structure, conduction and repolarization along with autonomic modulation appear to be useful in predicting the risk of a cardiac arrest after MI, particularly when assessed in combination. However, randomized trials assessing the efficacy of ICD therapy in patients identified as being at risk are required. Until such data are available, significant LV dysfunction alone and in combination with the induction of VT/VF during invasive testing in the nonacute post-MI period remain the only proven methods to guide prophylactic ICD therapy.

Delays and adverse clinical outcomes associated with unrecognized pacing indications

BACKGROUND

A recent UK audit showed that a significant proportion of patients who received pacemakers had pacing indications previously overlooked, leading to significant delays to pacemaker implantation.

AIM

To investigate the reasons for, and morbidity associated with, overlooked pacing indications.

DESIGN

Prospective observational study in a UK regional pacing centre and its referring district hospitals.

METHODS

Hospital records from referring and implanting centres were reviewed for 95 consecutive patients undergoing first pacemaker implant to determine symptoms, investigations and hospitalisations occurring after documentation of a pacing indication.

RESULTS

Thirty-three of ninety-five patients (35%) had a pacing indication overlooked, which was Class I in 14 patients and Class IIa in 19. Reasons for not making a pacing referral in these patients included: failure to recognize the indication in 14, making adjustments to potentially culprit medication in 15 and requesting additional 'confirmatory' tests in 4. Twenty-six patients (79%) with missed indications experienced adverse events after documentation of an indication, and before receiving a pacemaker: 23 had ongoing symptoms (including one cardiac arrest), three received temporary pacing wires and 18 were hospitalized with symptoms related to cardiac rhythm. Twenty-seven patients (82%) had a total of 38 additional specialist investigations after documentation of a pacing indication.

CONCLUSION

Documentation of an indication for pacing failed to trigger referral for permanent pacing in 35% of patients. This failure led to significant delays, morbidity and use of health service resource, which may have been avoided if timely recognition of the pacing indication had prompted referral. Failure to recognize pacing indications and reassessing symptoms and repeating investigation after changes to medication, often required for the management of associated tachyarrhythmias or other medical conditions, contribute to these delays, perhaps unnecessarily.

Novel pathway for sudden cardiac death prevention

Sudden cardiac death is one of the leading causes of death in the United States, accounting for an estimate 350,000 deaths each year. The US Congress passed a resolution in late September 2008 designating October as "National Sudden Cardiac Arrest Awareness Month." In an effort to raise awareness for preventing unnecessary deaths because of sudden cardiac death, the resolution "calls upon the people of the United States to observe this month with appropriate programs and activities." The response from our institute was to develop a novel pathway named ESCAPE-which is an evidence-based novel pathway for low Ejection fraction and Sudden Cardiac death Awareness and Prevention Eligibility. The main objective of this program is to demonstrate that implementing a simple novel pathway for primary prevention of sudden cardiac arrest leads to an increase in the number of patients with low ejection fraction (<or=35%) referred for implantable cardioverter defibrillators therapy. The key difference of our pathway compared with prior reported algorithms is that it is initiated at imaging laboratories. The registry will consist of consecutive patients presenting to our imaging laboratories (the echocardiography, the nuclear, and the cardiac catheterization laboratories). The ESCAPE pathway defines patients' management based upon 3 key parameters: left ventricular ejection function, heart failure functional class, and an evidence of a prior myocardial infarction or coronary artery disease. We hope that this new novel pathway will help to bridge the gap between the complex guidelines and the actual clinical practice and will help to save many lives.

Evaluating sex differences in population-based utilization of implantable cardioverter-defibrillators: role of cardiac conditions and noncardiac comorbidities

BACKGROUND

The influence of age and comorbidities on sex-specific implantable cardioverter-defibrillator (ICD) use for primary or secondary prevention is undefined.

OBJECTIVE

The purpose of this study was to investigate the influence of age and comorbidities on sex-specific ICD use.

METHODS

Sex disparities and sex-specific trends in ICD implantation according to indication in patients with cardiac arrest (1998-2007) in Ontario, Canada, were examined. Use of ICDs for primary prevention in patients with myocardial infarction (2002-2007) or heart failure (2005-2007) also was examined.

RESULTS

Among 9,246 eligible secondary prevention patients (age 66.3 +/- 14.3 years; 3,577 women [39%]) with cardiac arrest, men were more likely to undergo ICD implantation, with an age-, comorbidity-, and arrhythmia-adjusted hazard ratio (HR) of 1.92 (95% confidence interval [CI]: 1.66-2.23). Among 105,516 patients with myocardial infarction (age 68.3 +/- 12.7 years; 42,987 women [41%]), men were threefold more likely to undergo ICD implantation, with an adjusted HR of 3.00 (95% CI: 2.53-3.55). Among 61,160 patients with heart failure (age 76.2 +/- 12.0 years; 31,575 women [52%]), ICD implantation was more likely in men, with an adjusted HR of 3.01 (95% CI: 2.59-3.50). The odds of ICD implant for secondary prevention increased over time by 21% (95% CI: 13%-30%) in women and by 6% (95% CI: 2%-11%) in men, but rates of ICD use in men for primary prevention indications were persistently higher.

CONCLUSION

Men were more likely to undergo defibrillator implant than were women for primary and secondary prevention. Age and comorbidities did not account for the observed sex differences. Although sex differences in secondary prevention are declining over time, disparities in primary prevention persist.

New trends in treatment of hypertrophic cardiomyopathy

The management of patients with hypertrophic cardiomyopathy (HCM) has evolved markedly over the past 20 years, particularly with the rising number of indications for implantable cardiac defibrillators (ICDs) and alcohol septal ablation (ASA). However, medical therapies targeted to improve quality of life are underused; when resting and/or exercise obstruction is present, an incremental and additive approach should be used based on a high dosage of beta-blockers, verapamil and/or disopyramide. Radiofrequency catheter ablation of atrial fibrillation or A-V node has been proposed in some instances. Treatment of syncope or presyncope due to an abnormal blood pressure response during exercise remains challenging. Only patients with obstruction who remain severely symptomatic despite maximal medical therapy should be considered for invasive procedures, including dual-chamber (DDD) pacing, ASA or surgery. The reported complication rates of ASA (essentially complete A-V block, incidence above 5-10%, with mortality rates ranging from 0-4%) and the benefits at medium-term follow-up appear comparable to those observed after myectomy, which, according to guidelines, should remain the primary treatment for most severely symptomatic drug-refractory young patients with obstruction. While the overall survival of patients with HCM is similar to that of the general population, detection of patients at high risk of sudden cardiac death remains challenging, particularly in the young, and indications for ICDs in high risk patients without prior cardiac arrest should be patient- and family-orientated.

Association of physician certification and outcomes among patients receiving an implantable cardioverter-defibrillator

CONTEXT

Allowing nonelectrophysiologists to perform implantable cardioverter-defibrillator (ICD) procedures is controversial. However, it is not known whether outcomes of ICD implantation vary by physician specialty.

OBJECTIVE

To determine the association of implanting physician certification with outcomes following ICD implantation.

DESIGN, SETTING, AND PATIENTS

Retrospective cohort study using cases submitted to the ICD Registry performed between January 2006 and June 2007. Patients were grouped by the certification status of the implanting physician into mutually exclusive categories: electrophysiologists, nonelectrophysiologist cardiologists, thoracic surgeons, and other specialists. Hierarchical logistic regression models were developed to determine the independent association of physician certification with outcomes.

MAIN OUTCOME MEASURES

In-hospital procedural complication rates and the proportion of patients meeting criteria for a defibrillator with cardiac resynchronization therapy (CRT-D) who received that device.

RESULTS

Of 111,293 ICD implantations included in the analysis, 78,857 (70.9%) were performed by electrophysiologists, 24,399 (21.9%) by nonelectrophysiologist cardiologists, 1862 (1.7%) by thoracic surgeons, and 6175 (5.5%) by other specialists. Compared with patients whose ICD was implanted by electrophysiologists, patients whose ICD was implanted by either nonelectrophysiologist cardiologists or thoracic surgeons were at increased risk of complications in both unadjusted (electrophysiologists, 3.5% [2743/78,857]; nonelectrophysiologist cardiologists, 4.0% [970/24,399]; thoracic surgeons, 5.8% [108/1862]; P < .001) and adjusted analyses (relative risk [RR] for nonelectrophysiologist cardiologists, 1.11 [95% confidence interval {CI}, 1.01-1.21]; RR for thoracic surgeons, 1.44 [95% CI, 1.15-1.79]). Among 35,841 patients who met criteria for CRT-D, those whose ICD was implanted by physicians other than electrophysiologists were significantly less likely to receive a CRT-D device compared with patients whose ICD was implanted by an electrophysiologist in both unadjusted (electrophysiologists, 83.1% [21 303/25,635]; nonelectrophysiologist cardiologists, 75.8% [5950/7849]; thoracic surgeons, 57.8% [269/465]; other specialists, 74.8% [1416/1892]; P < .001) and adjusted analyses (RR for nonelectrophysiologist cardiologists, 0.93 [95% CI, 0.91-0.95]; RR for thoracic surgeons, 0.81 [95% CI, 0.74-0.88]; RR for other specialists, 0.97 [95% CI, 0.94-0.99]).

CONCLUSIONS

In this registry, nonelectrophysiologists implanted 29% of ICDs. Overall, implantations by a nonelectrophysiologist were associated with a higher risk of procedural complications and lower likelihood of receiving a CRT-D device when indicated compared with patients whose ICD was implanted by an electrophysiologist.

Paroxysmal atrioventricular block

Paroxysmal atrioventricular block (AVB) is a poorly defined clinical entity characterized by abrupt and unexpected change from 1:1 atrioventricular conduction to complete heart block, leading to syncope and potential sudden cardiac death. Although a dangerous condition because of unreliable escape mechanism, proper diagnosis of paroxysmal AVB is often missed and overlooked because of its unfamiliarity, unpredictability, and in some cases, no clear evidence of atrioventricular conduction disease during normal 1:1 conduction.

[Latest proceedings: remote medicine - ready for clinical practice?!]

Changes in the demographic structure, increasing multimorbidity in connection with a rise in the number of chronic illnesses and the absence of an effective coordination of the different levels of healthcare services with its discontinuous processes and redundancies will increase the economic burdens in the German health-care system. Recent developments and appropriate logistic premises nowadays offer a realistic basis for implementing remote medicine as a central service and information tool as well as an instrument controlling the information and data flow between patient, hospital and medical practitioner. This article highlights current and future strategies including diagnostic and therapeutic options. The focus will concentrate on patients with heart rhythm disturbances, advanced congestive heart failure, and patients with implantable devices, i.e., pacemaker and implantable cardioverter defibrillator (ICD).

Primary prevention with the ICD in clinical practice: not as straightforward as the guidelines suggest?

At first sight, guidelines for implantation of an implantable cardioverter defibrillator (ICD) for primary prevention of sudden cardiac death in patients with left ventricular systolic dysfunction seem unambiguous. There are clear cut-off values for ejection fraction, and functional class. However, determination of the ejection fraction itself is not unambiguous, and other risk factors for sudden death that may have a profound effect on risk are not used for decision-making. Furthermore, to obtain a clinically significant impact on survival, expected longevity is important as it can greatly compromise the benefit in elderly patients but underestimate the long-term potential of ICD therapy in younger patients. (Neth Heart J 2009;17:107-10.).

Meta-analysis of mortality in dialysis patients with an implantable cardioverter defibrillator

Patients receiving dialysis are at high risk for sudden cardiac death. Although clinical trials have shown that implantable cardioverter-defibrillators (ICDs) are effective in improving survival in a variety of populations, dialysis patients have been routinely excluded from these analyses. The purpose of this meta-analysis was to synthesize the available evidence regarding the effectiveness of ICD therapy in patients receiving dialysis. Medline, EMBASE, Web of Science, and Google Scholar were searched for pertinent studies published from 1999 to 2008. In addition, hand searches of the relevant annual scientific sessions and major scientific meetings in North America and Europe from 2000 to 2008 were performed. All clinical reports describing outcomes of ICD therapy in relation to renal function were eligible. Four investigators independently extracted the data in a standardized manner. Seven studies were identified, with a total of 2,516 patients and 89 patients receiving dialysis. Despite having ICDs, patients receiving dialysis had a 2.7-fold higher mortality compared with those not receiving dialysis. The results were similar in fixed- and random-effects models. Comparing patients receiving dialysis and those with chronic kidney disease but not receiving dialysis, there was no significant difference in mortality (risk ratio 1.62, 95% confidence interval 0.84 to 3.14). No evidence of publication bias was found. In conclusion, this meta-analysis suggests that even in those with ICDs, there is still a 2.7-fold increased mortality risk in patients who receive dialysis compared with those who do not. Beta blockers may be less cardioprotective in patients with ICDs who are on dialysis.

Anesthesia in the cardiac catheterization laboratory and electrophysiology laboratory

Procedures and interventions in the cardiac catheterization laboratory (CCL) and electrophysiology laboratory (EPL) are more complex and involve acutely ill patients. Safely caring for this growing patient population in the CCL and EPL is now a concern for all anesthesiologists and cardiologists. Anesthesiologists are uniquely trained to care for this complex patient population, allowing the cardiologist to focus on completing the interventional procedure successfully.

The work-up and management of patients with apparent or subclinical cardiac sarcoidosis: with emphasis on the associated heart rhythm abnormalities

In patients with newly diagnosed AV block and/or ventricular tachycardia, cardiac sarcoidosis should always be considered in the differential diagnosis. In addition to the pacemaker implant, cardiac resynchronization therapy (CRT) should be selected for severe heart failure patients who have class III or IV heart failure, LVEF <or=35%, and a complete LBBB pattern. If the disease activity is high, corticosteroid therapy is recommended. Patients with extracardiac sarcoidosis need to be closely followed for potential cardiac involvement, as the mortality in sarcoidosis depends on cardiac involvement. Early diagnosis and treatment of cardiac sarcoidosis is essential. Positron emission tomography (PET) and cardiac magnetic resonance imaging (MRI) are considered to have high sensitivity for cardiac involvement, and are the preferred imaging modalities. However, even in the era of new technology, such as PET and cardiac MRI, early diagnosis of cardiac sarcoidosis is still difficult.

The patient journey from symptom onset to pacemaker implantation

BACKGROUND

Regional variation in permanent pacemaker (PPM) implantation rates is well described, the reasons for which are unclear. Significant delays to PPM implantation in UK practice were described 20 years ago, but contemporary data are lacking.

AIM

To investigate delays to PPM implantation and their causes.

DESIGN

Prospective observational study in a UK regional pacing centre and its referring district hospitals.

METHODS

A total of 95 consecutive patients receiving first PPM implant for bradycardia indications from 1 June 2006 to 31 August 2006 were included. Hospital records from the referring and implanting centres were reviewed to determine the timings of: symptom onset; first hospital contact; documented pacing indication (defined by 2002 ACC/AHA/NASPE guidelines); referral to implanter; and PPM implantation.

RESULTS

Forty-eight patients (51%) were referred for pacing urgently; median delay from symptoms to PPM 15 days (range 0-7332 days). Forty-seven patients (49%) were referred electively; median delay from symptoms to PPM 380 days (range 33-7505 days), P < 0.0001. Twenty-three of the 47 elective patients (49%) had previous hospitalization with symptoms suggestive of bradycardia. Thirty-three of the 95 patients (35%) had a Class I or IIa pacing indication which did not trigger a pacing referral.

CONCLUSION

There are significant delays to PPM implantation in the United Kingdom, longer in those treated electively than those managed as emergencies. Some delays are due to 'process' problems including waiting lists, but a substantial proportion of patients had delays due to failure to refer for pacing once a pacing indication was documented.

Cardiac involvement in African and American trypanosomiasis

American trypanosomiasis (Chagas disease) and human African trypanosomiasis (HAT; sleeping sickness) are both caused by single-celled flagellates that are transmitted by arthropods. Cardiac problems are the main cause of morbidity in chronic Chagas disease, but neurological problems dominate in HAT. Physicians need to be aware of Chagas disease and HAT in patients living in or returning from endemic regions, even if they left those regions long ago. Chagas heart disease has to be taken into account in the differential diagnosis of cardiomyopathy, primarily in patients with pathological electrocardiographic (ECG) findings, such as right bundle branch block or left anterior hemiblock, with segmental wall motion abnormalities or aneurysms on echocardiography, and in young patients with stroke in the absence of arterial hypertension. In HAT patients, cardiac involvement as seen by ECG alterations, such as repolarisation changes and low voltage, is frequent. HAT cardiopathy in general is benign and does not cause relevant congestive heart failure and subsides with treatment. We review the differences between the American and African trypanosomiasis with the main focus on the heart.

Prognostic importance of defibrillator shocks in patients with heart failure

BACKGROUND

Patients with heart failure who receive an implantable cardioverter-defibrillator (ICD) for primary prevention (i.e., prevention of a first life-threatening arrhythmic event) may later receive therapeutic shocks from the ICD. Information about long-term prognosis after ICD therapy in such patients is limited.

METHODS

Of 829 patients with heart failure who were randomly assigned to ICD therapy, we implanted the ICD in 811. ICD shocks that followed the onset of ventricular tachycardia or ventricular fibrillation were considered to be appropriate. All other ICD shocks were considered to be inappropriate.

RESULTS

Over a median follow-up period of 45.5 months, 269 patients (33.2%) received at least one ICD shock, with 128 patients receiving only appropriate shocks, 87 receiving only inappropriate shocks, and 54 receiving both types of shock. In a Cox proportional-hazards model adjusted for baseline prognostic factors, an appropriate ICD shock, as compared with no appropriate shock, was associated with a significant increase in the subsequent risk of death from all causes (hazard ratio, 5.68; 95% confidence interval [CI], 3.97 to 8.12; P<0.001). An inappropriate ICD shock, as compared with no inappropriate shock, was also associated with a significant increase in the risk of death (hazard ratio, 1.98; 95% CI, 1.29 to 3.05; P=0.002). For patients who survived longer than 24 hours after an appropriate ICD shock, the risk of death remained elevated (hazard ratio, 2.99; 95% CI, 2.04 to 4.37; P<0.001). The most common cause of death among patients who received any ICD shock was progressive heart failure.

CONCLUSIONS

Among patients with heart failure in whom an ICD is implanted for primary prevention, those who receive shocks for any arrhythmia have a substantially higher risk of death than similar patients who do not receive such shocks.

What evidence do we have to replace in-hospital implantable cardioverter defibrillator follow-up?

INTRODUCTION

Due to the increasing number of patients with an implantable cardioverter defibrillator (ICD), new options for ICD patient follow-up management are required.

METHODS

Patients with ICD indication according to the guidelines received an ICD with Home Monitoring technology. The devices enabled the transmission of the relevant episode, therapy, and system integrity data. Patients were followed for 12 months with routine controls every 3 months. The physician analyzed the Home Monitoring data before the routine follow-up visit (FU) and gave a forecast on the necessity of the pending FU, which was compared with the evaluation after the FU. Based on the derived forecast reliability, a patient management scheme was developed and its impact on patient safety was assessed retrospectively.

RESULTS

A total of 271 patients were enrolled (40 f, mean age 62+/-12 years, mean LVEF 39+/-15%, 65% ischemic heart disease, 20% cardiomyopathy) and followed for 339+/-109 days. Of 908 pairs of Home Monitoring data and FU data evaluation, 129 there were false negative results for 92 patients. Safety concerns from false negative forecasts can be minimized with a patient management scheme containing the following elements: 1) never skip the first routine FU; 2) never skip a routine FU for a patient having already shown pacing threshold problems; 3) perform FU following hospitalizations; 4) perform FU following episode detection by the ICD; and 5) perform a routine FU if the patient reports symptoms. The retrospective analysis showed, that if the patients had been managed using this scheme, 503 of 1079 routine FU could have been skipped with only one safety concern, a three month delay in the detection of silent paroxysmal atrial fibrillation in one patient.

CONCLUSIONS

Home Monitoring in ICD therapy over 12 months is feasible. The data transmitted relevantly contribute to a remarkable reduction of follow-up burden and enable the individualization of routine follow-up.

Heart rate turbulence: a new predictor for risk of sudden cardiac death

Initial acceleration and a subsequent deceleration of sinus rhythm following a ventricular ectopic beat with a compensatory pause has been termed heart rate turbulence (HRT). The changes in sinus rhythm are thought to be mediated by a baroreflex response to the lower stroke volume of the ectopic beat. HRT is vagally mediated and abolished by atropine, whereas beta-blockers have no effect. HRT has been shown to be an independent and powerful predictor of mortality after myocardial infarction. In patients on beta-blockers, it scores better than left ventricular ejection fraction (LVEF) in its predictive value. Two common measures of HRT are turbulence onset and turbulence slope. When both these measures are abnormal, it is as powerful a predictor of mortality as LVEF. HRT correlates with other indices of cardiac autonomic functions like baroreflex sensitivity and heart rate variability. A composite autonomic index including all these three has been shown to be a powerful predictor of mortality. In patients undergoing direct percutaneous intervention for myocardial infarction, HRT improves in those attaining successful reperfusion. Abnormal values for HRT have been noted in patients with dilated cardiomyopathy and Chagas disease. Diabetic and elderly individuals are more likely to have blunted HRT. HRT cannot be measured in patients lacking ventricular ectopic beats and in patients presenting with atrial fibrillation.