Effectiveness of Implantable Cardioverter-Defibrillator Therapy for Heart Failure Patients according to Ischemic or Non-Ischemic Etiology in Korea

Ischemic cardiomyopathy: epidemiology, pathophysiology, outcomes, and therapeutic options

Ischemic cardiomyopathy (ICM) is the most prevalent cause of heart failure (HF) in developed countries, with significant morbidity and mortality, despite constant improvements in the management of coronary artery disease. Current literature on this topic remains fragmented. Therefore, this review aimed to summarize the most recent data on ICM, focusing on its definition, epidemiology, outcomes, and therapeutic options. The most widely accepted definition is represented by a left ventricular dysfunction in the presence of significant coronary artery disease. The prevalence of ICM is largely influenced by age and sex, with older individuals and males being more affected. Its pathophysiology is characterized by plaque buildup, thrombus formation, hypoperfusion, ischemic cell death, and left ventricular remodeling. Despite improvements in therapy, ICM still represents a public health burden, with a 1-year mortality rate of 16% and a 5-year mortality rate of approximately 40% in the USA and Europe. Therefore, optimization of cardiovascular function, prevention of progressive remodeling, reduction of HF symptoms, and improved survival are the main goals of treatment. Therapeutic options for ICM include lifestyle changes, optimal medical therapy, revascularization, device therapy, mechanical circulatory support, and cardiac transplantation. Personalized management strategies and tailored patient care are needed to improve the outcomes of patients with ICM.

Use of Implantable Cardioverter-Defibrillators for Primary Prevention of Sudden Cardiac Death in Asia

The effectiveness of primary prevention implantable cardioverter-defibrillators (ICDs) is well established. However, there are several unsolved problems related to ICD use for primary prevention in Asia, including ICD underuse, population differences in underlying heart disease, and the rate of appropriate ICD therapy compared with Western countries. Although the prevalence of ischemic cardiomyopathy in Asia is lower than in Europe and the United States, the mortality rate of Asian patients with ischemic heart disease has been increasing recently. As for the use of ICDs for primary prevention, there have been no randomized clinical trials, and limited data are available in Asia. This review focuses on the unmet needs related to ICD use for primary prevention in Asia.

End-of-Life Care for End-stage Heart Failure Patients

Although recent heart failure (HF) guidelines highlight integrative palliative care, including end-of-life (EOL), appropriate discussing EOL issues can be challenging due to possibility of unexpected deterioration throughout HF trajectory. Open communication and discussions with multidisciplinary team are important for setting patient and family expectations and establishing mutually agreed goals of care based firmly on the patient’s ‘human dignity’ and ‘right to self-determination.’ Especially when quality-of-life outweighs expanding quantity-of-life, transition to EOL care should be considered. Advanced care planning including resuscitation, device deactivation, site for last days, and bereavement support should focus on ensuring a good death, and be reviewed regularly.

Efforts to improve end-of-life (EOL) care have generally been focused on cancer patients, but high-quality EOL care is also important for patients with other serious medical illnesses including heart failure (HF). Recent HF guidelines offer more clinical considerations for palliative care including EOL care than ever before. Because HF patients can experience rapid, unexpected clinical deterioration or sudden death throughout the disease trajectory, choosing an appropriate time to discuss issues such as advance directives or hospice can be challenging in real clinical situations. Therefore, EOL issues should be discussed early. Conversations are important for understanding patient and family expectations and developing mutually agreed goals of care. In particular, high-quality communication with patient and family through a multidisciplinary team is necessary to define patient-centered goals of care and establish treatment based on goals. Control of symptoms such as dyspnea, pain, anxiety/depression, fatigue, nausea, anorexia, and altered mental status throughout the dying process is an important issue that is often overlooked. When quality-of-life outweighs expanding quantity-of-life, the transition to EOL care should be considered. Advanced care planning including resuscitation (i.e., do-not resuscitate order), device deactivation, site for last days and bereavement support for the family should focus on ensuring a good death and be reviewed regularly. It is essential to ensure that treatment for all HF patients incorporates discussions about the overall goals of care and individual patient preferences at both the EOL and sudden changes in health status. In this review, we focus on EOL care for end-stage HF patients.

Implantable Cardioverter-defibrillator Utilization and Its Outcomes in Korea: Data from Korean Acute Heart Failure Registry

BACKGROUND

There are sparse data on the utilization rate of implantable cardioverter-defibrillator (ICD) and its beneficial effects in Korean patients with heart failure with reduced left ventricular ejection fraction (LVEF).

METHODS

Among 5,625 acute heart failure (AHF) patients from 10 tertiary university hospitals across Korea, 485 patients with reassessed LVEF ≤ 35% at least 3 months after the index admission were enrolled in this study. The ICD implantation during the follow-up was evaluated. Mortality was compared between patients with ICDs and age-, sex-, and follow-up duration matched control patients.

RESULTS

Among 485 patients potentially indicated for an ICD for primary prevention, only 56 patients (11.5%) underwent ICD implantation during the follow-up. Patients with ICD showed a significantly lower all-cause mortality compared with their matched control population: adjusted hazard ratio (HR) (95% confidence interval [CI]) = 0.39 (0.16-0.92), P = 0.032. The mortality rate was still lower in the ICD group after excluding patients with cardiac resynchronization therapy (adjusted HR [95% CI] = 0.09 [0.01-0.63], P = 0.015). According to the subgroup analysis for ischemic heart failure, there was a significantly lower all-cause mortality in the ICD group than in the no-ICD group (HR [95% CI] = 0.20 [0.06-0.72], P = 0.013), with a borderline statistical significance (interaction P = 0.069).

CONCLUSION

Follow-up data of this large, multicenter registry suggests a significant under-utilization of ICD in Korean heart failure patients with reduced LVEF. Survival analysis implies that previously proven survival benefit of ICD in clinical trials could be extrapolated to Korean patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01389843.

Clinical Impact of Implantable Cardioverter-Defibrillator Therapy and Mortality Prediction Model for Effective Primary Prevention in Korean Patients

BACKGROUND

Studies on the efficacy of implantable cardioverter-defibrillator (ICD) therapy for primary prevention in Asian patients are relatively lacking compared to those for secondary prevention. Also, it is important to stratify which patients will benefit from ICD therapy for primary prevention.

METHODS

Of 483 consecutive patients who received new implantation of ICD in 9 centers in Korea, 305 patients with reduced left ventricular systolic function and/or documented ventricular fibrillation/tachycardia were enrolled and divided into primary (n = 167) and secondary prevention groups (n = 138).

RESULTS

During mean follow-up duration of 2.6 ± 1.6 years, appropriate ICD therapy occurred in 78 patients (25.6%), and appropriate ICD shock and anti-tachycardia pacing occurred in 15.1% and 15.1% of patients, respectively. Appropriate ICD shock rate was not different between the two groups (primary 12% vs. secondary 18.8%, P = 0.118). However, appropriate ICD therapy rate including shock and anti-tachycardia pacing was significantly higher (primary 18% vs. secondary 34.8%, P = 0.001) in the secondary prevention group. Type of prevention and etiology, appropriate and inappropriate ICD shock did not affect all-cause death. High levels of N-terminal pro-B-type natriuretic peptide, New York Heart Association functional class, low levels of estimated glomerular filtration ratio, and body mass index were associated with death before appropriate ICD shock in the primary prevention group. When patients were categorized in 5 risk score groups according to the sum of values defined by each cut-off level, significant differences in death rate before appropriate ICD shock were observed among risk 0 (0%), 1 (3.6%), 2 (3%), 3 (26.5%), and 4 (40%) (P < 0.001).

CONCLUSION

In this multicenter regional registry, the frequency of appropriate ICD therapy is not low in the primary prevention group. In addition, combination of poor prognostic factors of heart failure is useful in risk stratification of patients who are not benefiting from ICD therapy for primary prevention.

Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia: An Updated Review of Diagnosis and Management

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a condition caused by the replacement of the normal right ventricular myocardium with fibrofatty tissue. ARVC/D can present with a variety of clinical conditions including right ventricular dysfunction, ventricular tachyarrhythmias, sudden cardiac arrest, and sudden cardiac death (SCD). Since the first report of ARVC/D in 1982, many advances have been made in the diagnosis, genetic findings for pathology, and treatment. The 2010 International Task Force diagnostic criteria distinguish between major and minor criteria and focus on gross structural changes, microscopic changes, repolarization defects, conduction defects, arrhythmias, and family history. Implantable cardiac defibrillators and catheter ablation of the endocardium and epicardium with electromagnetic mapping have emerged as successful tools in the treatment and prevention of ventricular tachyarrhythmias and SCD. This review discusses the pathophysiology, genetics, diagnosis, and treatment advances in ARVC/D.

Trends in the use of implantable cardioverter-defibrillators for prevention of sudden cardiac arrest: A South Korean nationwide population-based study

BACKGROUND

The benefits of implantable cardioverter-defibrillators (ICDs) for the prevention of sudden cardiac arrest (SCA) are well established. However, a significant knowledge gap remains regarding current indications and utilization of ICDs in real-world settings in Asia.

METHODS

Patients who underwent ICD implantation in South Korea from 2007 to 2015 were identified using the Health Insurance Review and Assessment Service database. We investigated trends in use of ICD for the prevention of SCA.

RESULTS

A total of 4649 ICDs were implanted during 9 years. ICDs were implanted in 1448 (31.2%) patients for primary prevention and in 3201 (68.8%) for secondary prevention. The proportion of ICDs for primary prevention increased from 6.1% in 2007 to 41.9% in 2015. Primary prevention was more frequent in older (≥40 years) recipients (34.4% vs. 14.6%, P < .0001). The rates of ICD implantation for primary prevention were highest for nonischemic dilated cardiomyopathy (55.1%) and lowest (9.7%) for inherited primary arrhythmia syndrome (IPAS).

CONCLUSION

Our data showed a trend of progressively increasing rates of ICD implantation in Asia, especially for primary prevention of SCA. Primary prevention as an indication for ICD in patients with IPAS remained low.

Update on heart failure management and future directions

Heart failure (HF) is an important cardiovascular disease because of its increasing prevalence, significant morbidity, high mortality, and rapidly expanding health care cost. The number of HF patients is increasing worldwide, and Korea is no exception. There have been marked advances in definition, diagnostic modalities, and treatment of HF over the past four decades. There is continuing effort to improve risk stratification of HF using biomarkers, imaging and genetic testing. Newly developed medications and devices for HF have been widely adopted in clinical practice. Furthermore, definitive treatment for end-stage heart failure including left ventricular assist device and heart transplantation are rapidly evolving as well. This review summarizes the current state-of-the-art management for HF and the emerging diagnostic and therapeutic modalities to improve the outcome of HF patients.

Palliative and end-of-life care for heart failure patients in an aging society

The populations of Asian countries are expected to age rapidly in the near future, with a dramatic increase in the number of heart failure (HF) patients also anticipated. The need for palliative and end-of-life care for elderly patients with advanced HF is currently recognized in aging societies. However, palliative care and active treatment for HF are not mutually exclusive, and palliative care should be provided to reduce suffering occurring at any stage of symptomatic HF after the point of diagnosis. HF patients are at high risk of sudden cardiac death from the early stages of the disease onwards. The decision of whether to perform cardiopulmonary resuscitation in the event of an emergency is challenging, especially in elderly HF patients, because of the difficulty in accurately predicting the prognosis of the condition. Furthermore, advanced HF patients are often fitted with a device, and device deactivation at the end of life is a complicated process. Treatment strategies should thus be discussed by multi-disciplinary teams, including palliative experts, and should consider patient directives to address the problems discussed above. Open communication with the HF patient regarding the expected prognosis, course, and treatment options will serve to support the patient and aid in future planning.

Predictors of appropriate ICD therapy in Japanese patients with structural heart diseases: A major role of prior sustained ventricular tachycardia in secondary prevention

BACKGROUND

Implantable cardioverter defibrillator (ICD) and cardiac resynchronization with a defibrillator (CRT-D) are established therapies for secondary prevention of sudden cardiac death (SCD) in patients with structural heart disease (SHD), but the rates of subsequent ICD/CRT-D therapy widely differ among patients with SHD. The aim of this study was to determine clinical factors associated with appropriate therapy for preventing SCD in patients with SHD.

METHODS

We enrolled 147 patients with SHD (mean age, 59 ± 15 years; mean ejection fraction [EF], 45 ± 15%) who underwent ICD/CRT-D implantation for secondary prevention of SCD (ischemic heart disease, n = 50; nonischemic heart disease, n = 97). ICD/CRT-D was implanted for aborted cardiopulmonary arrest (CPA, n = 65) or sustained ventricular tachycardia (VT, n = 82).

RESULTS

During a follow-up period of 3.2 ± 3.6 years, 79 of the 147 patients had appropriate ICD/CRT-D therapies. A Kaplan-Meier survival curve showed that the rate of appropriate therapy was 54% at 5-year follow-up. Prior sustained VT, lower EF, and use of a class I antiarrhythmic drug were significantly more frequent in patients with appropriate therapy. In multivariate analysis, prior sustained VT (hazard ratio, 2.8; 95% CI, 1.60-4.46; P = .001) was the only independent predictor for appropriate ICD/CRT-D therapy. Kaplan-Meier survival curves showed that rates of appropriate therapy during a 5-year follow-up period were 70% and 34% in patients with sustained VT and those with CPA, respectively (P = .001).

CONCLUSIONS

In SHD patients implanted with an ICD/CRT-D, prior sustained VT as an indication of ICD/CRT-D implantation, but not EF or an antiarrhythmic drug, predicts a high rate of appropriate therapy.