LUX-Dx TRENDS Evaluates Diagnostics Sensors in Heart Failure Patients Receiving Boston Scientific's Investigational ICM System.

Key Inclusion Criteria: * Patient is currently in NYHA Class II or III. * For patients with LVEF \>40% measured on most recent available echocardiography within the previous 12 months: * ONE (1) of the following echocardiography findings: LA width (diameter) \>3.8 cm, LA length \>5.0 cm, LA area \>20 cm2, LA volume \>55 ml, LA volume index \>29 ml/m2, LVH defined by septal thickness or posterior wall thickness of \>1.1 cm AND * ONE (1) of the following: Elevated BNP/NT-proBNP as defined by: BNP \>100 pg/ml or NT-proBNP \>300 pg/ml within the previous 90 days for patients not in atrial fibrillation or BNP \>300 pg/ml or NT-proBNP \>900 pg/ml for patients in atrial fibrillation at the time of screening for eligibility OR Documented heart failure hospitalization or unscheduled heart failure IV therapy in the previous 12 months * For patients with LVEF \<40% (for MI patients, measured no less than 30 days post-MI) on most recent available echocardiography within the previous 12 months: * ONE (1) of the following: Elevated BNP/NT-proBNP as defined by BNP \>150 pg/ml or NT-proBNP \>600 pg/ml within the previous 90 days for patients not in atrial fibrillation or BNP \>450 pg/ml or NT-proBNP \>1800 pg/ml for patients in atrial fibrillation at the time of screening for eligibility OR Documented heart failure hospitalization or unscheduled heart failure IV therapy in the previous 12 months * Patient is willing to be monitored in LATITUDE Clarity and use the ICM patient mobile app. * Patient is of legal age to give informed consent and is willing to participate in the trial. Key Exclusion Criteria: * Patient is currently implanted with any other active electronic medical device. * Patient has undergone a heart transplant. * Patient is currently enrolled in another investigational study (excluding registries) without prior written approval from Boston Scientific. * Patient is known to be pregnant at the time of enrollment or plans to become pregnant during study participation. * Patient is diagnosed with amyloidosis or hypertrophic cardiomyopathy.