Atrial Fibrillation: Role of Cardiac Monitoring With Insertable Devices

Solomon J. Sager, MD: My name is Joey Sager. I’m the director of cardiac electrophysiology and the managing director of Chicago Cardiology Institute in Schaumburg, Illinois. We are a 17-provider group offering the full range of cardiac care. Today I’ll be talking to you about cardiac monitoring, including wearable monitors and insertable cardiac monitors. We’ll probably even touch on some of the patient-centered data collectors, such as the Apple Watch and the [AliveCor] KardiaMobile app.

What are the benefits of insertable cardiac monitors for cardiac monitoring? When we’re managing patients with heart rhythm disorders, the more data we can collect, the better it is for patient care. Insertable cardiac monitors allow us to collect data on a beat-by-beat basis for up to 3 to 4 years. They’re inserted very easily under the skin. It takes about 60 to 120 seconds, and can be done in the office.

The data we collect can guide a variety of clinical decision-making. It helps us guide medical management for patients with atrial fibrillation [A-Fib]. It helps guide what ablations we may want to perform based on whether the A-Fib is paroxysmal, persistent, or even permanent. It helps us decide whether patients have enough A-Fib that would warrant anticoagulation, and it helps guide decisions regarding antiarrhythmic therapy. Sometimes patients have palpitations, and we’re not sure if they have atrial fibrillation. The insertable cardiac monitor can help us diagnose atrial fibrillation in those patients.

Atrial fibrillation is the new paradigm for insertable cardiac monitors. We used to use them only for syncope, for cryptogenic stroke, or for undiagnosed symptoms. But as the usage of insertable cardiac monitors and the technology has improved, we’ve started to use it much more for the management of A-Fib. The data we collect over a period of time can help us determine the best course of treatment for our patients and individualize the care for each patient. It’s a powerful tool, and patients have to do minimal activity to generate the data. The monitor for the device just sits by their bed, and overnight the communicator by the bed sends the data to a web-based portal that doctors and technicians can gather information from every morning to help us guide clinical decision-making.

How can we use insertable cardiac monitors to guide management of our patients with A-Fib? Two important factors for A-Fib are catheter ablation and anticoagulation. Frequently after catheter ablation, we’re able to discontinue some medications depending on the amount of A-Fib that the patients have afterward. Using insertable cardiac monitors after catheter ablation allows us to confirm that they’re not having any more atrial fibrillation and that we can indeed safely stop antiarrhythmic drugs.

Anticoagulation can be a little more of a challenge. As you probably know, we make decisions on anticoagulation based mostly on a score called the CHA2DS2-VASc [congestive heart failure, hypertension, age, diabetes mellitus, stroke, vascular disease, age, sex category] score, which is the best predictor of whether a patient is at increased risk for stroke. However, there are patients who are at the borderline of needing anticoagulation, as well as lower-risk patients who may want to know whether they’re having more A-Fib to help guide their anticoagulation decisions. In these circumstances, it’s not unreasonable to use the data collected from the insertable cardiac monitor to help guide therapy regarding anticoagulation. As many of you probably know from treating patients with A-Fib, many patients are adverse or just adamantly don’t want to take anticoagulation. The insertable cardiac monitor allows us to monitor those patients for any A-Fib recurrence and their overall A-Fib burden to see whether we need to continue to aggressively pursue anticoagulation.

What are the limitations of insertable cardiac monitors? From an implantation perspective, there are very few limitations. The complication rate is less than 1%. The main complication we occasionally see is bleeding at the site of where we insert the monitor. Very rarely you can have an infection, although that’s less than 1 of 1000. Some limitations are that it doesn’t allow us to collect real-time data. The data are transmitted only via the monitor by the bedside. Although some of the newer ICMs [implantable cardiac monitors] are able to connect via the phone using Bluetooth. I always warn my patients that these data aren’t collected in real time and that if they go into A-Fib at, say, at 2 PM, then I may not find out until the next morning.

Some of the other limitations are that it can overdiagnose A-Fib or underdiagnose it. Sometimes atrial flutter can present as a regular rhythm that the device, if the rate is slow enough, may not detect if the rate is regular and resembles normal sinus rhythm. At other times the device may think that it’s seeing pauses or may think it’s seeing fast rates if it’s over- or undersensing. There are new machine-learning algorithms to help prevent this from happening, but they don’t completely eliminate them. Sometimes we think we detect arrhythmias or other things when those aren’t there. Careful analysis of the strips from the device can usually eliminate this, but that adds to the time it takes to manage these patients.

Transcript Edited for Clarity