Examining the Role of CRT-D in Improving Outcomes in Patients With Heart Failure

In a review of the literature, this author looks at the use and potential benefits of cardiac resynchronization therapy defibrillators (CRT-Ds) within the treatment armamentarium. By Frieda Wiley

Heart disease remains the number one killer in the United States of both men and women, serving as the underlying cause in one out of every four deaths, according to the Centers for Disease Control and Prevention. All too often, heart failure and its associated symptoms present in the disease spectrum. Approximately 6.2 million people living in the United States have heart failure, and the condition claimed 37.9 million lives in 2018. In 2012, heart disease accounted for more than $30.7 billion in annual spending, costs which included health services, medications, and labor loss.

When is CRT-D An Appropriate Therapeutic Option in Treating Heart Failure?

Medication intervention using beta blockers and digoxin has mortality and symptomatology benefit in managing heart failure. However, these medications cannot address the challenges associated with heart failure patients who face an increased risk for sudden cardiac death. While implantable cardioverter defibrillators (ICDs) help improve ventricular synchronicity in this patient population, patients face the risk of electrical storm, a factor known to increase mortality and decrease quality of life. Fortunately, coupling ICD with cardiac resynchronization therapy, or a cardiac resynchronization therapy defibrillator (CRT-D), offers hope to this subpopulation of patients with heart failure.

“When you look at CRT-D, generally it will mean the patient hasn’t experienced sudden cardiac death or ventricular death,” said Patrick McCann, MD, the medical director of heart failure and mechanical circulatory support at Prisma Health USC Medical Group in Columbia, South Carolina.

Such patients tend to present with a certain group of clinical features. Accord- ing to McCann, the electrocardiograms for these patients show widened QRS intervals. In addition, the condition typically affects patients who have heart failure, defined as New York Heart Association (NYHA) classes II-IV with an ejection fraction that falls below 35 percent. CRT-D is indicated for patients who also have a widened QRS interval. The QRS typically exceeds 120 ms, and CRT-D generally proves more beneficial for patients whose QRS exceeds 150 ms. The five-year survival rate for patients who receive CRT-D device placement
is 50 percent, and patients with CRT-D placement fare better than those who receive ICD only. A study following 19,935 patients living the United States between 2004 and 2016 found that patients with the CRT-D implant faced a lower risk of electrical storm than those who received ICD only.

CRT-D is contraindicated in patients who have less than a year of life left and a current history of metastatic cancer regardless of the prognosis.

Dr. McCann says the preclusions apply regardless of whether the patient is taking a medication with a proven mortality benefit in heart failure, such as the beta-blocker propranolol. The same holds true in the case that the patient might
be taking a medication that can either cause or exacerbate heart failure, such as the cancer medication doxorubicin or the antihyperglycemic agent rosiglitazone.

“In general, medications that affect heart failure make no difference in patients with life expectancies of less than one year,” noted Dr. McCann.

Having an ongoing infection is another important contraindication because it increases the risk of the device becoming infected. Similarly, non-adherence to treatment plans is another barrier. According to Dr. McCann, such patients are often even less likely to adhere to a medication regimen after device placement than they were prior to having CRT-D because they think the device eliminates the need to take medication, according to Dr. McCann.

Why Appropriate Timing and Device Placement are Critical

Several factors play a role in in achieving optimal outcomes in CRT-D. Timing is one of those factors.

“Timing a big part of it because the majority of the patients have significant heart failure,” explained Dr. McCann. “The patients who stand to benefit most from CRT-D have NYHA Class I or Class II because CRT-D doesn’t really make as much of a difference with Class IV.”

Ensuring optimal device placement during the patient’s heart failure journey requires both a prudent eye as well as early identification.

One critical contributor to appropriate timing of device placement is ensuring the patient is seen or, as Dr. McCann explained, “…getting these people in sooner rather than later for earlier diagnosis.”

In addition, successful outcomes depend on a clinician’s ability to select the appropriate device for the patient. After all, there are several different types of defibrillators from which to choose, and not all devices are created equal.

For example, another device, called a biventricular pacemaker, or cardiac resynchronization therapy placement (CRT- P), may be more suitable for patients with bradycardia whose left and right ventricles do not beat synchronously. In the case of patients with prolonged QRS intervals, McCann says a CRT-D device is better because it contains an ICD that not only supports the synchronization of the left and right ventricles but also treats sudden arrythmias that can lead to sudden cardiac death. However, device placement is just one part of the equation. Success requires patient adherence to medical therapy as well as routine follow-up in electrophysiology studies.

For patients who are eligible for CRT-D, education proves one of the most critical elements to treatment.

“When you see the benefits for these patients in previous trials, all these patients were on previous heart failure therapy,” explained McCann. “Some patients thought they didn’t have to take the meds after getting the therapy, but the reality is that the device is an adjunct in care.”

Normally, remote follow-up for CRT-D devices occurs every three months, meaning that clinicians can download the data remotely. Newer devices allow daily remote interrogation.

Recognizing the Clinical Challenges With CRT-D

As with any treatment, CRT-D has its share of clinical hurdles. While prompt diagnosis is a key factor that influences outcomes, placement of a CRT-D device does not always guarantee therapeutic success either.

“Approximately 30 percent of people are non-responders, meaning that they get an additional lead placed with CRT-D devices, but they either get a suboptimal response or don’t respond at all,” noted Dr. McCann.

As previously noted, adhering to maintenance medical therapy can also present a challenge. Equally as taxing, however, is the significant lack of therapy guidelines for patients with heart failure. These circumstances become even more com- plicated because the subpopulation of heart failure patients who have a CRT-D placement often do not understand why they have multiple doctors. For example, an electrophysiologist bears the responsibility of placing the device, but a cardiologist would adjust the pharmacological treatment. Dr. McCann says the patients need to understand that these nuances are important.

Palliative care can also be particularly taxing for both the patient and the clinician, especially when it comes to end-of- life discussions.

“When patients are going to die, it’s a significantly emotional conversation because it’s difficult explaining to some- one that it’s a much more peaceful death than being shocked several times as you die,” noted Dr. McCann.

Sometimes, as the patient dies, the heart will go into an abnormal rhythm. This is the case with sudden cardiac death. ICD will shock the patient’s heart into rhythm, but heart failure is a different situation. Instead of shocking the patient back into sinus or another more normal rhythm, the device begins to shock the patient.

“It’s also hard for some people to wrap their minds around the idea that turning off the CRT-D does not mean they’re giving up,” noted Dr. McCann.

It can be difficult for patients to understand that the pacemaker cannot resuscitate them. In fact, by the time
the patient dies, the myocardium has become too weak to react to any signals delivered by the pacemaker. Education
as well as counseling services play a key role in improving the patient’s knowledge and acceptance of the circumstances. Dr. McCann and his team routinely recruit the services of his clinic’s palliative care colleagues to assist with this process.

Final Notes

When it comes to assessing current and emerging modalities for CRT-D, Dr. McCann believes clinicians have reasons to be optimistic. Emerging modalities offer improved algorithms to help track heart failure exacerbations. This translates to better outcomes in terms of quality of life as well as less time in the clinic.

“These technological gains increase the access to care because remote and daily monitoring allow you to act sooner than later,” pointed out Dr. McCann. “These are some of the emerging modalities for CRT.”