Author + information
- Rajat Deo, MD, MTR∗ ( and )
- Andrew E. Epstein, MD
- Electrophysiology Section, Division of Cardiovascular Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- ↵∗Reprint requests and correspondence:
Dr. Rajat Deo, Electrophysiology Section, Division of Cardiovascular Medicine, University of Pennsylvania, 3400 Spruce Street, 9 Founders Pavilion, Philadelphia, Pennsylvania 19104.
Sudden cardiac arrest is defined as an unexpected, pulseless condition attributable to a cardiac arrhythmia (1). Most cardiac arrests present without warning symptoms and are nearly always fatal despite resuscitation attempts (2,3). Given these poor outcomes, few studies have evaluated the long-term prognosis among individuals who have survived cardiac arrest. Initial, large-scale data emerged from investigators who evaluated 1-year outcomes after hospital discharge among nearly 7,000 elderly survivors of an in-hospital cardiac arrest (4). In their primary analysis, these investigators demonstrated that the majority of survivors who were discharged were alive after 1 year, and their 3-year mortality rate was similar to that of patients who had been discharged after a heart failure hospitalization.
Over the last several years, resuscitation programs have focused on early interventions and evidence-based practices to improve cardiac arrest outcomes. Studies now assess the impact of these changes and are evaluating clinical outcomes among individuals who survive out-of-hospital cardiac arrests (OHCAs). In a recent study that utilized data from the Danish Cardiac Arrest Registry, investigators evaluated rates of sustainable employment among adults who survived a cardiac arrest (5). Among 796 adults who survived a month after a cardiac arrest, more than three-fourths returned to work at a median time of 4 months. This seemingly high rate of functionality appeared to be associated with bystander-witnessed arrest and bystander cardiopulmonary resuscitation—both of which have been a focus of public health interventions in Denmark and across the world. Further, in comparison to earlier studies, these investigators also detected a significant decline in the proportion of patients with anoxic brain injury.
Moving forward in this continuum of understanding prognosis among cardiac arrest survivors, in this issue of the Journal, Fordyce et al. (6) evaluated mortality and readmission outcomes in myocardial infarction patients aged ≥65 years with an OHCA. They demonstrated that the presence of an OHCA did not affect 1-year survival if the patient was discharged to a nonhospice facility. Their study design included patients from the National Cardiovascular Data Registry (NCDR) Acute Coronary Treatment and Intervention Outcomes Network Registry–Get with the Guidelines (ACTION Registry–GWTG), which is a U.S. registry that enrolls patients with ST-segment elevation or non–ST-segment elevation MI. In addition, these investigators linked the registry with the Centers for Medicare & Medicaid Services claims data to assess post-discharge outcomes. The findings from this study complement the earlier, in-hospital cardiac arrest survival analyses, which suggest the possibility of a favorable prognosis among elderly patients who survive to hospital discharge (4) and another that indicates worse outcomes in survivors of in-hospital cardiac arrest compared with survivors of OHCA (7). As clinicians, we must appreciate the value that emergency medical services, advanced resuscitation units, and medical technology have provided in changing the course of what used to be a universally fatal condition.
In the course of their analysis, Fordyce et al. (6) remind us of ongoing efforts that need to be prioritized in order to make a greater impact in improving OHCA survival. As highlighted in their introduction, the occurrence of OHCA carries an extremely poor prognosis. The findings from the ACTION Registry–GWTG support this claim, because approximately one-half of the OHCA patients brought to the hospital died compared with 6% in the group that did not have OHCA. Furthermore, a significantly greater percentage of the OHCA patients were discharged to hospice facilities compared with those without OHCA. These poor short-term outcomes correlate with their gravity of cardiovascular disease as reflected by a much higher prevalence of cardiogenic shock upon admission (27% vs. 2%), higher rates of heart failure, recurrent cardiac arrest, and major bleeding. Although the authors demonstrate that older patients with MI and OHCA surviving to hospital discharge (not hospice) have comparable 1-year mortality and health care utilization rates than those without OHCA, OHCA with MI is neither inconsequential nor benign. Equally noteworthy and not included in the current analysis are the approximately one-half to a majority of patients with cardiac arrests attributable to MI who die out-of-hospital and never even make it to the emergency department or hospital, especially among elderly patients (3). Further, for those who reach the hospital, many die or are discharged to hospice, which is hardly a perfect outcome. If the authors compared the outcomes of all MI patients with and without OHCA who survive to hospitalization and include in-hospital deaths and discharges to hospice, the long-term survival after cardiac arrest would not appear as favorable. As a result, despite the advanced resuscitative and cardiovascular interventions that are present and available to our country’s elderly population, the paper by Fordyce et al. (6) highlights the need for earlier interventions to prevent the devastating complications of cardiac arrest whether it be associated with MI or not.
Recently, the Institute of Medicine published Strategies to Improve Cardiac Arrest Survival: A Time to Act in which it emphasized the need for more effective prevention and resuscitation programs (8). In this document, the Institute of Medicine highlights wide diversity in survival rates among communities and hospitals in the United States and noted that resuscitation outcomes for ventricular tachyarrhythmias can range from <10% to >50% depending on the community’s emergency response system. As such, multiple organizations and stakeholders have highlighted the need to implement evidence-based programs that involve early and effective cardiopulmonary resuscitation and early defibrillation.
There are several limitations to this paper that bear mention. First, the definition of OHCA included not only patients who received external defibrillation, but also those who were pulseless, but did not receive attempts at defibrillation or chest compression by emergency medical services personnel. We do not know what proportion of patients qualified for the study by this criterion: if it was a significant proportion, the study population may have included a “healthy” segment of individuals who actually did not have an arrhythmic arrest at all, but rather had hypotension or bradycardia associated with their infarctions. These may have importantly contributed to the population that survived to discharge and not gone to hospice. Second, it is very difficult to account for how comorbidities may have influenced outcomes, not only overall survival, but also survival to discharge home and not hospice. Note that survivors with OHCA compared with those without OHCA were younger and less likely to have diabetes, peripheral arterial disease, chronic lung disease, or prior revascularization. They may have been so-called “healthy responders,” one form of bias in clinical trials (9).
In view of the preceding discussion, there is a desperate need for additional research on developing new therapies for the prevention of cardiac arrest. Understanding that the key to reducing the public health burden from this condition will arise from upstream interventions, we need a more sophisticated and rigorous approach to cardiac arrest prevention. Although the objective of the current paper was to assess long-term outcomes among MI survivors, the study design reminds us of our fundamental lack in understanding the biological and disease variables that result in MI to present with cardiac arrest versus classic, crushing chest discomfort. Understanding the specific arrhythmic risk factors and disease markers associated with cardiac arrest will help to determine the feasibility of novel risk stratification and treatment strategies in high-risk subgroups of the general population. At present, risk stratification and prevention efforts have been directed toward patients with advanced cardiomyopathies. In particular, current practice utilizes left ventricular ejection fraction to guide implantable cardioverter-defibrillator therapy for the primary prevention of sudden cardiac death. However, as reflected by ACTION Registry–GWTG, in which <20% of the patients had a history of heart failure, the majority of cardiac arrests in the population will occur among those without advanced cardiovascular disease. Earlier, upstream interventions and therapies should continue to be our focus so that we can continue making strides in this seemingly random condition.
↵∗ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
Both authors have reported that they have no relationships relevant to the contents of this paper to disclose.
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