Wearable Defibrillator Can Prevent Sudden Death in Cardiac Sarcoidosis Patients, Study Shows

Ana Pena, PhD avatar

by Ana Pena, PhD |

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A wearable cardioverter-defibrillator can prevent sudden death in patients with cardiac sarcoidosis, new research demonstrates.

A study found the device was capable of restoring heart rhythm in all patients who experienced abnormal and potentially life-threatening heartbeats.

Results were reported in the study, “Management of sudden cardiac death in cardiac sarcoidosis using the wearable cardioverter defibrillator,” published in the journal PLOS One.

About 5 percent of sarcoidosis patients are reported to have heart involvement in their disease, but some studies indicate that the condition remains undiagnosed in many patients. In Europe, for instance, cardiac sarcoidosis is estimated to affect about 25 percent of all sarcoidosis patients.

The presence of cardiac sarcoidosis worsens the prognosis and increases the risk of malfunctions in the electrical activity of the heart, such as ventricular tachycardia/fibrillation and heart failure.

Ventricular tachycardia and fibrillation are both arrhythmias, which are abnormal or irregular beatings of the heart that happen when the lower chambers of the heart, called the ventricles, beat faster than normal (in ventricular tachycardia) or when they quiver or “fibrillate” instead of pumping the blood (in ventricular fibrillation).

Both conditions, especially fibrillation, are serious, life-threatening conditions that can lead to cardiac arrest and sudden death. They need to be treated immediately.

Sudden death in people with ventricular tachycardia or fibrillation can be prevented using an implantable cardioverter defibrillator (ICD), a device placed beneath the skin that continuously monitors the heart and delivers an electric shock to restore the normal beat if an abnormal rhythm is detected.

Among cardiac sarcoidosis patients with an ICD, it is estimated that patients receive a shock to treat a ventricular tachycardia or fibrillation episode at a rate of 7.1 percent per year, which underscores the high number of serious heart events in these patients.

But in cases where an ICD implant is not appropriate or when the risk of ventricular tachycardia or fibrillation is due to transient or treatable causes, a wearable cardioverter-defibrillator (WCD) offers an alternative approach. It works like an ICD, but it’s an external device, consisting of a garment and a monitor worn by the patient.

The effectiveness of the WCD has been proven in several studies that  report it was able to restore a regular heart rhythm 91-99 percent of the time after a ventricular tachycardia or fibrillation event.

In the retrospective study, researchers examined the outcomes of 46 cardiac sarcoidosis patients who wore a wearable cardioverter-defibrillator from January 2005 to June 2014.

Patients had a median age of 48, and most had a reduced left ventricular ejection fraction (the fraction of blood that the left ventricle pumps out with each contraction) — about 30 percent. All patients wore the device nearly all the time (a median of 23.6 hours every day).

Throughout the study, 10 patients had 11 episodes of ventricular tachycardia or fibrillation from the study’s first day up to 79 days after they started using the WCD.

Electrocardiogram recordings of patients treated by WCD shocks revealed that five episodes were due to ventricular tachycardia, three to ventricular fibrillation, and three to ventricular tachycardia degenerating into fibrillation.

The WCD was able to restore a regular heartbeat in all cases after delivering the first shock. The survival rate 24 hours after the shock was 100 percent, with all patients surviving the episodes.

One patient had another episode of ventricular tachycardia or fibrillation days later, and required four shocks for the heart rhythm to recover.

“Management of sudden cardiac death among cardiac sarcoidosis patients was aided by the wearable cardioverter defibrillator resulting in successful termination of ventricular tachycardia/fibrillation upon delivery of shock,” the researchers wrote.

Some patients stopped using the WCD. The most common reason was because they replaced it with an ICD implant (in seven of the 10 patients who received a shock).

Among patients who were not shocked, 16 also received an ICD, while seven other patients discontinued wearing it because they achieved improved left ventricular ejection fraction (the amount of blood pumped through the ventricle).

“The WCD can prevent [sudden cardiac death] in sarcoidosis patients with known, or suspected, cardiac involvement until optimized long term treatment strategies can be attained,” researchers wrote.

“Due to the need for ongoing immunosuppression therapy and the potential for some patients to improve, not all patients should be immediately implanted with an ICD,” they added.