Wearable Cardioverter Defibrillators (WCDs) for Protection From Sudden Cardiac Death (SCD): The AHA/ACC/HRS Guidelines

Can you tell us about the recently published AHA/ACC/HRS Guidelines for the wearable cardioverter defibrillator? 

These multi-societal Guidelines on wearable cardioverter defibrillator (WCD) use were a part of a broader update to the guidelines for the Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death (SCD).¹ Importantly, the new Guidelines represent the broadest, most comprehensive formal recommendations to date for the use of the WCD.

The Guidelines recommend consideration of the WCD for indicated patients. This population includes patients with recent myocardial infarction and left ventricular dysfunction, who may or may not have undergone revascularization, as well as patients with newly diagnosed cardiomyopathies, both ischemic and non-ischemic in etiology. Guideline recommendations for consideration of the WCD equally support its use in both ischemic and non-ischemic patients.

Do the AHA/ACC/HRS Guidelines for use of the WCD mirror the 2015 ESC Guidelines? 

While the class of recommendation for the WCD in the AHA/ACC/HRS Guidelines is consistent with the 2015 European Society of Cardiology Guidelines, the level of evidence to support the use of WCD therapy is higher in these new Guidelines. The level of evidence in the current multi-societal AHA/ACC/HRS Guidelines is based on the ongoing evolution of clinical data demonstrating the effectiveness of the WCD during the period of highest SCD risk. Benefits of WCD therapy have been consistently demonstrated in studies covering tens of thousands of patients. 

The new Guidelines also recommend the concept of shared decision-making approaches. For a patient with left ventricular dysfunction, shared decision-making between the patient and their clinicians will include patient education about the risk for SCD and treatment options available to them. This includes the possibility of WCD therapy, and consideration of more permanent protection. Not every patient will go on to receive an implantable defibrillator nor is it clinically indicated. The need for shared decision-making underscores the importance of screening all potentially indicated patients for SCD after a new diagnosis or a recent cardiac event, in order to discuss treatment options with patients and involve them in their care.

Can you summarize some of the clinical data that support the use of the WCD?

I want to highlight two different categories of evidence: the body of evidence showing the risk of SCD for patients with impaired ejection fraction following a cardiac event, such as an myocardial infarction or a new diagnosis of heart failure; and data that demonstrates WCD effectiveness.

First, the level of evidence supporting recommendations for the WCD outlined in the AHA/ACC/HRS Guidelines should raise awareness about the very high risk of SCD. A number of studies have demonstrated that patients with recent myocardial infarction and left ventricular dysfunction are at very high risk for SCD. 

These studies range from the VALIANT trial to the ACC National Cardiovascular Data Registry (NCDR), to other trials in acute myocardial infarction, such as the CADILLAC study. Altogether, these studies show that patients with a recent myocardial infarction and with left ventricular dysfunction (commonly defined as having an ejection fraction of ≤35%) are at a very high risk for SCD, particularly within the first 30 to 90 days after their initial event. The risk is independent of whether these individuals undergo revascularization. The average time to SCD is 11 days after the initial event, meaning that many patients are outside of the hospital setting; they have already been discharged to home or another care facility. The fact that over 80% of SCD events occur after hospital discharge highlights the importance of screening, and the need for awareness of and consideration for a therapy that can help to mitigate that risk. 

Second, there is a wealth of evidence to support the efficacy of the WCD as a tool to reduce SCD. WEARIT-II was a prospective, WCD registry of approximately 2000 patients² that highlighted the utility of the device, not only with regard to patient compliance and adherence to the therapy, but also by documenting a high rate of ventricular tachycardia (VT)/ventricular fibrillation (VF) within a short period of 90 days following a cardiac event. The registry also demonstrates the utility of a wearable defibrillator as a tool to aid long-term decision-making: future treatment can involve the need for an implantable defibrillator, or the recovery of left ventricular dysfunction and continuing with medical therapy alone. 

Other data showing the efficacy of the wearable defibrillator and the frequency of the need for treatment with the device include a large study of almost 10,000 patients, led by Dr. Andrew Epstein³, that raised awareness that most of these patients receive the therapy within the first month of wearing the WCD, if they do have an event. 

You mentioned the importance of screening patients for risk of SCD.  What might that look like? 

This is really an all-hands-on-deck call for healthcare practitioners, independent of their specialty or sub-specialty, to partner together to implement screening protocols. Interventional cardiologists are at the front lines of encountering patients who are at the greatest risk for SCD, such as patients who present with acute myocardial infarction and have left ventricular dysfunction. Interventional cardiologists implement initial therapy, i.e., angioplasty and stenting, although we may not necessarily see these patients throughout their entire hospital course, as many other physicians can become involved in the care of these patients. That being said, interventional cardiologists are in the best position to identify and screen all patients who are potentially indicated for the therapy. 

There is evidence to suggest that as many as one in three patients are never screened for SCD risk; this is something that needs to be addressed. Three lives per day are saved with the WCD.⁴ The avoided outcome is mortality, obviously very meaningful. The Guidelines are a call to action from a multidisciplinary perspective for all healthcare practitioners to screen and engage in shared decision-making with patients at risk for SCD who might be indicated for a WCD. 

We know from general practice in cardiovascular medicine that the recommendation by societal guidelines is one of the most effective and meaningful ways to change the course of care for patients at a national or international level, beyond just the work of an individual physician or an individual institution itself. With regard to the risk of SCD, there is nothing unique about the patients from one institution to another in this country or other countries. Screening for a WCD should be part of protocol and care pathways. Quality improvement initiatives are routinely incorporated into care pathways and this should be one of them, so we can ensure that all indicated patients are protected during the period of highest SCD risk while we determine their best long-term care plan. 

Can you share an example of a patient that was helped by a WCD?

I could reference many patients from personal experience who have benefited from the WCD, and this equally includes an even greater number of WCD patients who fortunately did not require therapy. We had a recent patient who experienced a myocardial infarction, and was discharged with a WCD. He was later treated by the WCD, and then subsequently presented to an emergency room close to his home for follow-up.  

We have other patients who haven’t been treated by the WCD, but who consider the reassurance offered by the device to be an important element of their recovery in that it increases their confidence to perform activities of daily living.

After a patient experiences a treatment from a WCD, what happens?  

If a patient experiences a treatment event resulting from a potentially life-threatening arrhythmia, it usually occurs in less than a minute from when the event begins to the delivery of the treatment shock. In part because of the rapidity of the treatment, most patients regain consciousness immediately. At that point, the WCD instructs them to call their doctor. Patients will commonly call their physician and may present to an emergency room. There will be some interaction with the patient and the physician, and if the physician is knowledgeable of that patient’s condition, they will discuss whatever follow-up steps are necessary and determine the appropriate long-term care plan. 

What do we know about long-term outcomes for WCD patients?

In terms of what happens to patients over longer-term follow-up², in the WEARIT-II registry, following WCD use, about 40% of the patients had an improvement in their ejection fraction, to the point where an implantable cardioverter defibrillator was no longer indicated. Similarly, an almost equal number of patients, at the end of wearing the WCD, required an implantable defibrillator. 

In addition, the WEARIT-II registry assessed even longer-term outcomes and found that 96% of the patients prescribed the WCD were alive at 1 year. There was no difference in survival between patients with ischemic or non-ischemic cardiomyopathy. Of note, the WCD can also identify clinically actionable events, including clinically relevant events such as other types of arrhythmias: supraventricular arrhythmias or non-sustained ventricular arrhythmias that don’t translate to a therapy. Data captured by the patient’s WCD are transmitted to an online patient data management system website, where it can be archived for physician review.

Is 90 days the standard period for use?

Yes, the typical wear time for patients with a WCD is approximately 90 days. We know from previous studies that adherence to the WCD through roughly a 90-day period is very high and patients wear it the majority of a 24-hour day. By far, in selected patients — those with recent myocardial infarction and advanced left ventricular dysfunction — numerous clinical studies have demonstrated that the risk of mortality is highest in the first 90 days following an event like a heart attack or a new diagnosis of heart failure. The risk of SCD is especially high within the first 30 days, but overall, it is high within the first 90 days. It parallels current practice Guidelines with regard to consideration of and screening for an implantable defibrillator. 

What would you like to see in the future for the WCD?

We continue to realize, through clinical trials, the potential of this therapy. The recommendation and inclusion of the WCD in the recent multi-societal Guidelines provides healthcare practitioners not only an opportunity, but guidance, to protect people from unnecessary death. At least three lives each day are saved with this therapy, and it is very easy to implement. 

The benefit of the technology far exceeds any potential inconvenience or risk. Hospitals and healthcare providers can integrate the use of a WCD into care pathways, and this is the future of this device. We would only expect the use of this therapy to become a routine standard of care after a cardiac event or a new diagnosis of a cardiomyopathy. The AHA/ACC/HRS Guidelines are a call to action to all practitioners involved in the care of those with cardiovascular disease to screen for patients who are indicated for the therapy. 

While some would argue that a 1 to 1.5% risk of SCD is a low-frequency event, the outcome is death, the most meaningful outcome that can be avoided. Further, when taken into consideration this event frequency is for such a short period of time of 90 days following an acute cardiac event, the rate is in fact relatively high. Any potentially effective therapy to avoid and reduce that risk would be welcomed. Changing paradigms of therapy based on such perceived low event rates is not unique in cardiovascular medicine. We as interventional cardiologists have changed our entire practices around the risks of stent thrombosis that are <1%. We have changed our treatments so that angioplasty and stenting are preferred over thrombolytic therapy for differences in mortality of <1%. We now have a very simple and yet very effective therapy to reduce mortality when the risk is 1-1.5%. It would be a meaningful action.

Do you ever have patients refuse the device?

The short answer is yes, and even more so, we have patients who refuse an implantable defibrillator. The reasons are multifactorial and a broader discussion altogether, but the conversation that the practitioner has with the patient, whether it be with regard to the WCD, an implantable defibrillator, or any other surgical procedure or revascularization, imparts a responsibility to the healthcare provider to not only understand the data, but translate it to the patient in an understandable and meaningful way. Now, this concept of shared decision-making is included as a recommendation in these multi-societal Guidelines. Practitioners should discuss the recommendations and level of evidence, and weigh the risks and benefits, so that the patient and their family can understand and make a decision based on quality information. In other words, it should not be a conversation of “we want you to wear this device” and “oh, I don’t want it” or “yes, I’ll wear it”, but instead, be a more meaningful, involved discussion between the patient and physician.  

Any final thoughts?

The take-home message is that following a cardiac event, such as a heart attack or new diagnosis of heart failure, patients with reduced left ventricular function are at risk for SCD and they need protection. We know the influence of societal guidelines on changing practice; thus, it is important for physicians to have this formal recommendation for the use of the WCD. The new Guidelines are based on an even greater accrual of evidence with the WCD and offer recommendations on the implementation of a potentially life-saving therapy into our daily practice. Shared decision-making to incorporate patient values and preferences are a welcome addition to the Guidelines. 

References

1. Al-Khatib SM, Stevenson WG, Ackerman MJ, et al. 2017 AHA/ACC/HRS Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2017 Oct 24. pii: S0735-1097(17)41305-2. doi: 10.1016/j.jacc.2017.10.053. [Epub ahead of print]
2. Kutyifa V, Moss AJ, Klein H, et al. Use of the wearable cardioverter defibrillator in high-risk cardiac patients: data from the Prospective Registry of Patients Using the Wearable Cardioverter Defibrillator (WEARIT-II Registry). Circulation. 2015 Oct 27;132(17): 1613-1619. doi: 10.1161/CIRCULATIONAHA.115.015677. 
3. Epstein AE, Abraham WT, Bianco NR, et al. Wearable cardioverter-defibrillator use in patients perceived to be at high risk early post-myocardial infarction. J Am Coll Cardiol. 2013 Nov 19; 62(21): 2000-2007. doi: 10.1016/j.jacc.2013.05.086. 
4. ZOLL LifeVest Wearable Defibrillator proven safe and effective in largest German Registry. Available online at https://www.zoll.com/news-releases/2016/08/25/lifevest-safe-effective-german-registry/. Accessed January 19, 2018.

Disclosure: Dr. Kandzari reports receiving modest consulting honoraria from ZOLL.

Dr. Kandzari can be contacted at david.kandzari@piedmont.org.