3. ACE inhibitor iii. Physical evaluation consistent with worsening HF signs (i.e. elevated JVP, ankle edema, dyspnea, abdominal distension, >4 lb or >1.8 kg weight increase in past week) iv. HF admission in last 30 days with a documented BNP > 300 pg/mL (or NT-pro-BNP > 1500 pg/mL) during or since admission AND d. Presence of left ventricular systolic dysfunction (ejection fraction <40%); e. Successfully trained and deemed proficient on how to perform a fingerstick and to use the Test System. Each subject will undergo two proficiency assessments.