Patients with heart failure (HF) represent a large population of patients who are at high risk for complications related to undiagnosed atrial fibrillation (AF). However, currently there are limited modalities for early AF detection and subsequent stroke prevention in this high-risk population. An implantable cardiac monitor (ICM) is inserted subcutaneously and can provide long term arrhythmia information via remote monitoring.

The ASSERT-AF study seeks to accurately define the burden of AF and other arrhythmias in high-risk HF patients using an ASSERT ICM.

Over 6 million people in the United States suffer from heart failure (HF). By the year 2030 the prevalence of HF is expected to exceed 8 million people. Heart failure accounts for 1 million hospital admissions each year, costing our economy in excess of $30 billion dollars per year. Mortality in patients with HF remains high, and nearly half of all patients diagnosed with HF will die within 5 years. More than half of all patients admitted with HF decompensation have preserved left ventricular systolic function. Patients with HF and mildly reduced or preserved left ventricular systolic function are at high risk for developing atrial fibrillation (AF), the occurrence of which often contributes to HF decompensation and increases morbidity and all-cause mortality. Similarly, patients with AF are at high risk for developing HF due to loss of atrio-ventricular synchrony and rapid uncontrolled ventricular rates. Detection of AF can be challenging and may go undiagnosed in asymptomatic or minimally symptomatic patients through conventional monitoring methods. Patients with HF represent a large population who are at risk for complications related to undiagnosed AF. AF increases the risk of stroke five-fold and the risk of death nearly two-fold. Moreover, strokes related to AF are twice as likely to be fatal or severely disabling compared to strokes due to other causes, such as ischemic small vessel disease or atheromatous large vessel disease. Cardiac implantable electronic devices (CIEDs), can be used for the early detection of AF in asymptomatic or mildly symptomatic patients with HF. However, current guidelines provide an indication for prophylactic implantable cardioverter defibrillator (ICD) only in HF patients with left ventricular ejection fraction (LVEF) ≤ 35%, whereas there are limited data for device-based detection of AF in HF patients with more preserved LVEF.

Implantable cardiac monitors (ICM) are devices that can be injected into the subcutaneous tissue and can provide automatic electrocardiographic recordings of asymptomatic arrhythmias as well as patient triggered electrocardiographic recordings of symptomatic episodes during long term follow-up. Implantable cardiac monitors are be paired with remote monitoring systems, capable of rapid remote review of electrograms. Accordingly, we hypothesize that a management strategy that incorporates ICM implantation in patients with HF and LVEF >35% will result in a significantly higher rate of AF detection leading to arrhythmia related interventions compared to conventional monitoring and follow-up in patients with HF.

Inclusion Criteria:

• Male and female patients more than 18 years of age (no upper age limit)
• HF exacerbation requiring initiation or augmentation of decongestive therapy in a hospital setting (hospitalization or emergency department visit) during the past 24 calendar months prior to consent date OR current treatment with loop-diuretics (furosemide, bumetanide, or torsemide).
• LVEF > 35% on a cardiac imaging study (echocardiogram, nuclear imaging, cardiac magnetic resonance imaging) performed during the past 24 calendar months prior to consent date
• One or more FDA-approved indications for an Abbott ICM (unexplained symptoms such as: dizziness, palpitations, chest pain, syncope, and shortness of breath, as well as patients who are at risk for cardiac arrhythmias).
• Willing to undergo an Abbott ICM implant and agree to remote ICM monitoring.

Exclusion Criteria:

• Existing implantable cardioverter defibrillator (ICD), biventricular ICD, implantable cardiac monitor or pacemaker.
• Known or documented history AF or atrial flutter any time in past.
• Has had a heart transplant
• Participation in other clinical trials (observational registries are allowed with approval from the Coordination Center)
• Unable or unwilling to cooperate with the protocol
• Unable or unwilling to sign the consent for participation

Events Review Committee: A blinded three-member Events Review Committee will review de-identified source documents obtained from each of the enrolling sites that will only be labelled with a subject ID. No data will be provided indicating the randomized treatment arm to the study and appropriately redacted with no ICM data provided. The information will be used to determine the nature of any clinical and adverse events. Available medical records and source documents will be used to determine cause-specific mortality.