Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities - Research Paper Example

? Guidelines for the device based therapy of cardiac rhythm abnormalities. al Affiliation: Cardiac arrhythmias are significantly associated with high risk of death. Sudden cardiac death is a major sequel of arrhythmias. Devices that include cardioverter-defibrillators and cardiac resynchronization therapy are the main stay of prevention of sudden cardiac death in patients with cardiac arrhythmias.. Implantation of cardiac devices is done under the guidelines of the American Heart Association, recommended in year 2008. Several studies have evaluated the guidelines and identified the significant benefits of implant of cardiac devices in patients after myocardial infarction, heart failure, symptomatic left ventricular dysfunction. Recommendations in guideline for the device based therapy of cardiac rhythm abnormality has proved to be beneficial for reducing the risk of sudden cardiac death and has improved quality of life. However, multi-centric clinical trials are needed to find an optimal timing for the implant for an indication. Guidelines for device based therapy of cardiac rhythm abnormalities. Cardiac arrhythmias are still a major threat to human health and are so deadly that they are responsible for 50% of all the cardiovascular deaths related to the cardiovascular system (Piccini, Al-Khatib, Myers, Anstrom, Buxton, Peterson, & Sanders, 2010). Arrhythmias are not always pathological; they can be physiological like bradycardia in athletes and tachycardia during anxiety. Physiological cardiac arrhythmias usually do not need any treatment, they are recovered spontaneously but, pathological arrhythmias require heroic management. Anti- arrhythmic drugs and anti-arrhythmic devices are employed as a treatment strategy for arrhythmias. Implantable cardioverter-defibrillator, pacemakers and cardiac resynchronization therapy are the devices used to prevent death from arrhythmia; use of anti-arrhythmic devices are significantly associated to reduce mortality associated with arrhythmia (Piccini et al., 2010). Devices are used to prevent arrhythmia according to the guidelines of the American Heart Association, published in 2008. Guidelines for device based therapy of cardiac rhythm abnormalities were designed by experts from the American College of Cardiology in collaboration with the American Association of Thoracic Surgery and Society of Thoracic Surgeons. The Recommendations were made after a thorough literature search so that treatment strategy can be standardized and clinical evaluation of patients can be made easy. The Guidelines aim to reduce inappropriate decisions for implantation of cardiac devices, provide confidence to cardiac consultants.When related to devices, guidelines are meant for promotion of their appropriate use and to abandon it’s under and over use (Epstein et al., 2008). Critical evaluation of all diagnostic procedures, diagnostic scales, and guidelines is necessary because it is directly related to appropriate health care delivery ( Epstein et al., 2008). Evidence based critical evaluation of guidelines is a scientific means to judge effectiveness of the guideline in promoting good patient care. Critical evaluation of the guidelines for device based therapy is inevitable to judge the pros and cons of the guideline; it also helps to find any danger, if associated with the recommendations. Scientific critics of the guideline are important means to generate new recommendations in order to make the guideline more favorable. Since it is related to the cardiology, critical evaluation of the guidelines for the implanted anti-arrhythmic devices are more demanding because negligence may take a patient's life in a few minutes. The nursing staff is usually the first hand care providers in hospital settings. Being medical professionals, it is inevitable for them to understand the importance of guidelines; they should know the recommended guidelines of device based management of cardiac arrhythmias because after treatment, patient’s follow-up is necessary to decide about its prognosis and nursing staff is a major part of the follow-up medical team. With the reference of guidelines they can solve queries of patients and their attendants, related to the treatment, in a more scientific way. Through in depth knowledge of the guidelines, nurses would be able to diagnose and pick the likely candidate for device based management of arrhythmias. Health care providers should know the guidelines so that they can manage emergency cases of arrhythmias through external defibrillators and pacemakers. Nurses should be aware of critical evaluation of the guideline and recommendations about it so they can work with doctors, as a unit to ensure excellent health care and case management. Theoretical foundation: Pathology of Cardiac arrhythmias: Regular Contraction and subsequent relaxation of the heart is maintained by highly organized electrical conduction system which consists of sino-atrial node, atrio-ventricular node, bundle of His, right and left bundle branches, and purkinji fibres. The conduction system is responsible for co-ordinated atrial and ventricular systole and diastole (Kummar, Abbas, Fausto, &Aster, 2010). Electrical conduction system is vulnerable to hypo and hyperkalemia, changes due to autonomic nervous system, ischemia and hypoxia; they may cause arrhythmias including atrial fibrillation, ventricular fibrillation, bradycardia and asystole (Kumar, Abbas, Fausto, &Aster, 2010). Arrhythmias can be sustained or sporadic. Any insult to the electrical conduction pathway may lead to un-coordinated myocardial contractions because the myocardium has the innate ability of self-pace making. Pacemakers in the myocardium other than sino-atrial node generate arrhythmias. Arrhythmic heart is unable to maintain cardiac output so symptoms of hypotension ensue. Low blood supply to the vital organs appears deadly for organs like kidney, brain and heart.Arrhythmias can lead to sudden death. Devices to control arrhythmias: Arrhythmias are controlled and prevented through defibrillators, cardiac resynchronization and pace makers. They sense abnormal beats and with the help of electric shocks, heart rhythm is set back to a regular rhythm. In cases of bradycardia, implanted pacemakers provide electrical impulses to the myocardium so that it can contract and relax accordingly. Guidelines for the use of Implanted Cardioverter–Defibrillator (ICD): Class I Recommendation: Implanted Cardioverter-Defibrillator device is indicated in: Patients having history of ventricular fibrillation or sustained ventricular tachycardia with irreversible cause of ventricular tachycardia or fibrillation (level of evidence A) (Epstein et al., 2008). People with congenital heart defects, either haemodynamically stable or not, presented with spontaneous and sustained ventricular tachycardia (level of evidence B) (Epstein et al., 2008). Syncope due to undetermined cause with the clinically relevant and haemodynamically significant sustained ventricular tachycardia or ventricular fibrillation is induced at electrophysiological studies (level of evidence B) (Epstein et al., 2008). Post- myocardial infarction patients, when their Left ventricular ejection fraction is less than or equal to 35% after 40 days of prior myocardial infarction and, they are in NHYA functional class II or III (level of evidence A) (Epstein et al., 2008). Patients of non-ischemic dilated cardiomyopathy in NHYA functional class II or III with left ventricular ejection fraction of less than or equal to 35% (level of evidence B) (Epstein et al., 2008). Patients, who have passed 40 days after the myocardial infarction and have ventricular dysfunction with a left ventricular ejection fraction of less than or equal to 30%, and are in NHYA functional class I (level of evidence A) (Epstein et al., 2008). Patients having a history of myocardial infarction and are presented with non-sustained ventricular tachycardia, left ventricular ejection fraction of less than or equal to 40% and inducible ventricular tachycardia or ventricular fibrillation on electrophysiological studies (level of evidence B) (Epstein et al., 2008). Class IIa Recommendations: Implanted cardioverter-defibrillator device can be employed in: Patients with unexplained syncope, significant left ventricular dysfunction, and non-ischemic dilated cardiomyopathy (level of significance C) (Epstein et al., 2008). Patients having sustained ventricular tachycardia with normal or near normal ventricular functions (level of significance C) (Epstein et al., 2008). Patients with hypertrophic cardiomyopathy with risk of sudden cardiac death (level of evidence C) (Epstein et al., 2008). Patients of arrhythmogenic right ventricular dysplasia with risk factors of sudden cardiac death (level of evidence C) (Epstein et al., 2008). People with long QT syndrome who develops syncope or ventricular tachycardia after taking beta-blocker (level of evidence B) (Epstein et al., 2008). People awaiting heart transplant (level of evidence C) (Epstein et al., 2008). Patients having Brugada syndrome and had syncope or had ventricular tachycardia (level of evidence C) (Epstein et al., 2008). Patients with Chagas disease, giant cell myocarditis, or cardiac sarcoidosis (level of significance C) (Epstein et al., 2008). Patients with catecholaminergic polymorphic ventricular tachycardia and had syncope or sustained ventricular tachycardia after taking beta-blockers (level of significance C) (Epstein et al., 2008). Class IIb Recommendation: Implanted Cardioverter-Defibrillator may be considered in: Left ventricular ejection fraction of 35% or less in patients with non-ischemic heart diseases who are in NHYA functional class I (level of significance C) (Epstein et al., 2008). Patients with long QT syndrome with the risk of sudden cardiac death (level of evidence B) (Epstein et al., 2008). Patients with syncope and advanced structural heart disease in whom all invasive and non-invasive diagnostic technique failed to establish a cause (level of evidence C) (Epstein et al., 2008). Patients with Left ventricular non compaction (level of evidence C) (Epstein et al., 2008). Patients having familial cardiomyopathy associated with sudden death (level of evidence C) (Epstein et al., 2008). Class III Recommendations: Implanted Cardioverter-Defibrillator is not recommended for: Patients who do not have a reasonable expectation of survival (level of evidence C) (Epstein et al., 2008). Patients with incessant ventricular tachycardia or ventricular fibrillation (level of evidence C) (Epstein et al., 2008). Patients having reversible cause of ventricular tachycardia (level of evidence C) (Epstein et al., 2008). Patients having significant psychiatric problems (level of evidence C) (Epstein et al., 2008). Ventricular tachycardia or ventricular fibrillation amenable to surgery (level of evidence C) (Epstein et al., 2008). Syncope of undefined origin without an inducable ventricular fibrillation (level of evidence C) (Epstein et al., 2008). NYHA class IV patients with drug-refractory heart failure and also unfit for cardiac transplant and cardiac resynchronization therapy (level of evidence C) (Epstein et al., 2008). Literature Review: Scholarly articles published during the period of 2008- 2012 were reviewed through Pubmed central and Google scholar. Keywords employed are as follows: defibrillators, cardiac arrhythmias, prophylaxis, implanted cardioverter, sudden cardiac death, ventricular fibrillation. Articles are selected due to their relevance to the evaluation of guidelines for device based treatment of cardiac arrhythmias. Articles only from peer reviewed journals of cardiology are used. Significance of ICD in post-MI patients: Piccini and colleagues discussed about optimal timings for implant of a cardioverter-defibrillator in patients who had myocardial infarction. They carried an observational study to evaluate the benefits of early implantation of a cardioverter defibrillator (level of evidence for the study is B). Piccini et al. (2010) developed a Markov model for implantation of a cardiovertor defibrillator in post myocardial infarction patients who need an ICD according to AHA guidelines, 2008. Patients were grouped into four categories; a group of patient was managed only on medical therapy and no ICD was implanted, other three groups were implanted with an ICD after 60days of onset of myocardial infarction, after 6 months, and after 1 year of the myocardial infarction. Deterministic model was used for follow up. Patients were followed after 10 years of their hospital discharge. Piccini et al found a significant difference in probability of survival of between patients who received ICD and who have not received an ICD (level of evidence B) They also reported that earlier ICD implantation after MI is modestly beneficial to increase life expectancy but no significant decline in the probability of survival is reported after delayed implantation. They proposed that implantation of an ICD is crucial for post MI patients who meet the guideline, regardless of implantation timing (Piccini et al, 2010). Piccini and colleagues also discussed that if ICD is implanted during the 40 day period after MI, it may be related to increased risk of non-arrhythmogenic death (2010). The study was consistent with class I recommendation in AHA guidelines for implantation of a cardiovertor-defibrillator. Implantation of Cardioverter-Defibrillatorin patients with Non Compaction Cardiomyopathy: Caliskan et al. (2011) evaluated the guideline for the use of implantable cardiac defibrillator in patients with non-compaction cardiomyopathy and found that when the implantable cardiac defibrillator was used appropriately according to current guideline, it is related to the prevention of sudden cardiac death (level of evidence B). Caliskan et al. (2011) conducted a cohort study on 44 adult patients of non compaction cardiomyopathy. Out of 44, 32 patients had received implantable cardiovertor-defibrillator for primary prophylaxis of sudden cardiac death and 12 received it for prevention of sudden cardiac death after the episode of myocardial infarction . Regular follow up of the patients was done after 3-6 months and values for variables were recorded. Caliskan and colleagues analyzed that during follow up, 8 patients presented with appropriate ICD therapy and 9 presented with inappropriate ICD shocks. Significant drop in sudden cardiac death was observed by the use of ICD (2011). Premature ventricular contractions were more commonly observed on electrocardiogram of the patients implanted with ICD but Caliskan et al. (2011) reported that premature ventricular contractions do not create much problem for patients with non compaction cardiomyopathy. Caliskan et al. (2011) carried the study on rare non-ischemic cardiomyopathy and it has supported the Class IIb recommendations of current AHA guideline for the use of an implantable cardiovertor-defibrillator in patients with non-compaction cardiomyopathy. Implantable Cardioverter-Defibrillator in Cardiomyopathy: Bhonsale et al. (2011) conducted the study related to implantation of a cardioverter-defibrillator in patients with arrhythmogenic right ventricular dysplasia\cardiomyopathy. The observational study was conducted on 84 patients, among whom 70 were definitive and 14 were probable cases of arrhythmogenic right ventricular dysplasia. Implantable cardioverter-defibrillators were implanted in 84 patients and all patients were followed for a mean duration of 4.7 years (Bhonsale et al., 2011). The study reported that 40 patients had appropriate ICD therapy, especially in the first year of implantations. 20 Patients had device related complication. The study had pointed out some risk factors for the appropriate ICD therapy (Bhonsela et al, 2011). Bhonsela et al. (2011) reported that implantation of a cardioverter-defibrillator as a primary prophylaxis against sudden cardiac death had appropriate ICD therapy and an estimated survival time can be increased by the use of ICD so that lethal arrhythmias can be avoided. Study of Bhonsela et al favors the Class IIb recommendation of the guideline for device based therapy of cardiac arrthmias (level of evidence B). Critique against ICD: Tung, Zimetbaum, & Josephson (2011) reported after critically evaluating several clinical trials for ICD that Implantable cardioverter-defibrillators may prevent sudden death, but there are number of patients who do not get benefit from ICD and for them, an ICD is a source of device related complication and compromise on patient’s quality of life (level of evidence C). The current guideline is unable to categorize the patient according to the benefit that they can get through ICD (2008). The study by Tung et al. (2011) supports the role of ICD for the prevention of arrthmias, but it has been demanded that guidelines should be more sophisticated to prevent overuse of ICD subsequently, maximizing the benefits to the patients. Guidelines for Cardiac Resynchronization therapy (CRT): Class I Recommendations: Cardiac Resynchronization therapy is recommended in patients of heart failure that are managed with appropriate medical treatment and are having NYHA functional class III or IV, sinus rhythm, QRS complex greater than or equal to 0.12 seconds, left ventricular ejection fraction of less than or equal to 35% . ICD can be used with CRT (level of evidence A) (Epstein et al., 2008). Class IIa Recommendations: Cardiac Resynchronization therapy is appropriate for patients of heart failure that are managed with recommended medical treatment and are having NYHA functional class III or IV, atrial fibrillation, QRS complex greater than or equal to 0.12 seconds, left ventricular ejection fraction of less than or equal to 35%. ICD can be used with CRT in this case (level of evidence B) (Epstein et al., 2008). Cardiac Resynchronization therapy is also logical to use in patients of heart failure that are dependent on ventricular pacing despite being taking recommended medical treatment and are having NYHA functional class III or IV (level of evidence C) (Epstein et al., 2008). Class IIb Recommendations: Patients of heart failure that are on optimal recommended medical treatment, having NYHA functional class I or II and are undergoing implantation of an ICD or permanent pace maker can be helped with the CRT implant (level of evidence C) (Epstein et al., 2008). Class III Recommendations: Cardiac Resynchronization therapy is not indicated in: Asymptomatic patients with reduced left ventricular function in whom other indications of cardiac pacing are absent. (Level of evidence B) (Epstein et al., 2008). Patients of chronic diseases with less survival time (Level of evidence C) (Epstein et al., 2008). Literature review: PubMed central was employed to search for scholarly articles published in peered review journals during the period of 2008- 2012. Cardiac resynchronization therapy, heart failure, left ventricular ejection fraction, and cardiac pacing were used as search terms. CRT for Asymptomatic or mildly symptomatic patients: Daubert et al. (2009) conducted a randomized control trial REVERSE, to assess the efficacy of Cardiac Resynchronization Therapy in asymptomatic or mildly symptomatic patients with left ventricular dysfunction with NYHA functional class I or II (2009) 287 patients participated in the study. Cardiac resynchronization therapy is implanted in 266 patients, reported implantation success rate is 97%. Randomization was done and 180 patients were entered in group of CRT ON patients and 82 were in group of CRT OFF patients. Patients were called at 1, 3, 6, 12, 18, 24 months of implantation for follow up (Daubert et al., 2009) Daubert et al. (2009) found in their study that when CRT is implanted in Patients of left ventricular dysfunction who are asymptomatic or mildly symptomatic, it appeared beneficial for the patients because it reduced risk of progression of diseases, delayed admission due to heart failure and reversed the cardiac remolding that had occurred as a result of ventricular dysfunction (Level of evidence B). The guideline suggests that CRT is not indicated in asymptomatic patients when they do not need any cardiac pacing (Epstein et al., 2008). Findings in trial presented by Daubert et al. (2009) are inconsistent with the current guideline; however several large randomized trials can establish the diagnosis. Reynolds and Jessup discussed in their article about CRT that trials had proven the efficiency of CRT implant in patients with heart failure with NYHA functional class III or IV by reducing heart failure mortality in them. Moreover, they have mentioned the RAFT study, published in 2010 showing an efficiency of the CRT for the decline of mortality among patients of left ventricular dysfunction presented with mild symptoms (2011). Reynold and Jessup included the Meta-analysis by Al-Majed and colleagues that stressed on not to use the CRT for asymptomatic or mildly symptomatic patients because the use of a CRT may provide benefit presented in the REVERSE trial but CRT fails to improve the quality of life in mildly symptomatic patients. They have critically evaluated the REVERSE and RAFT trials (2011). In his critical review, Reynold and Jessup supported the current guideline for the use of CRT (level of evidence C). Recommendations for practice: From the above literature review, it is evident that most of the researchers are in favor of the current guidelines for the device based therapy of cardiac arrhythmias, but patients who could get maximum benefit should be identified and should not over do because unnecessary implants may pose a serious threat to patients’ health. Multi-centric trials should be done to establish the recommendation for RCT in patients with mild symptoms of left ventricular dysfunction. Conclusion: Beyond doubt, the current guideline by American Heart Association for device based therapy of cardiac arrhythmias is well justified but it fails to categorize the patients for level of benefit: moreover, it has not mentioned the optimal time for the implantation after arrhythmias. More researches are needed to solve the unanswered questions. References: Piccini, J. P., Al-Khatib, S., Myers, E. R., Anstrom, K. J., Buxton, A. E., Peterson, E. D., and Sanders, G. D. (2010).Optimal timing of implantable cardioverter-defibrillator implantation after myocardial infarction: A decision analysis. Journal of Cardiovascular Electrophysiology, 21 (7), 791-798. Epstein, A. E., DiMarco, J.P., Ellenbogen, K. A., Estes III, N. A. M., Freedman, R. A., Gettes, L.S.,… Sweeney, M. O. (2008). ACC/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: Executive summary. Circulation, 117, 2820-2840. Kumar, V., Abbas, A. K., Fausto, N., Aster, J. C. (2010).The Heart. Schmitt, W., and Gruliow, R (Eds.) Robins and Cotran Pathologic Basis of Diseases (pp.529-587). Philadelphia: Elsevier. Caliskan, K., Torok, T. S., Theuns, D. A. M. J., Kardos, A., Geleijnse, M. L., Balk, A. H. M. M., … Simoons, M. L. (2011). Indications and outcome of implantable cardioverter-defibrillators for primary and secondary prophylaxis in patients with non compaction cardiomyopathy. Journal of Cardiovascular Electrophysiology, 22 (8), 898-904. Bhonsale, A., James, C. A., Tichnell, C., Murray, B., Gagarin, D., Philips, B., … Calkins, H. (2011). Incidence and predictors of implantable cardioverter-defibrillator therapy in patients with arrhythmogenic right ventricular dysplasia\ cardiomyopathy undergoing implantable cardioverter-defibrillator implantation for primary prevention. Journal of American College of Cardiology, 58 (14), 1485-1496. Tung, R., Zimetbaum, P., and Josephson, M. E. (2008).A critical appraisal of implanted cardioverter-defibrillator therapy for the prevention of sudden cardiac death. Journal of American College of Cardiology,52 (14), 1111-1121. Daubert, C., Gold, M. R., Abraham, W. T., Ghio, S., Hassager, C., Goode, G.,…Linde, C. (2009). Prevention of disease progression by cardiac resynchronization therapy in patients with asymptomatic or mildly symptomatic left ventricular dysfunction: Insights from the European cohort of the REVERSE (Resynchronization Reverses Remodeling in Systolic Left Ventricular Dysfunction) Trial. Journal of American College of Cardiology, 54 (20), 1837-1846. Reynolds, C. R., Jessup, M. (2011). Translating the benefits of cardiac resynchronization therapy widely and wisely: Challenges remain. Annals of Internal Medicine, 154, 436-438. Read More