We sought to determine the utility of combined heart failure (HF) device diagnostic information to predict clinical deterioration of HF in patients with systolic left ventricular dysfunction. Some implantable devices continuously monitor HF device diagnostic information, but data are limited on the ability of combined HF device diagnostics to predict HF events. The PARTNERS HF (Program to Access and Review Trending Information and Evaluate Correlation to Symptoms in Patients With Heart Failure) was a prospective, multicenter observational study in patients receiving cardiac resynchronization therapy (CRT) implantable cardioverter-defibrillators. HF events were independently adjudicated. A combined HF device diagnostic algorithm was developed on an independent dataset. The algorithm was considered positive if a patient had 2 of the following abnormal criteria during a 1-month period: long atrial fibrillation duration, rapid ventricular rate during atrial fibrillation, high (≥60) fluid index, low patient activity, abnormal autonomics (high night heart rate or low heart rate variability), or notable device therapy (low CRT pacing or implantable cardioverter-defibrillator shocks), or if they only had a very high (≥100) fluid index. We used univariate and multivariable analyses to determine predictors of subsequent HF events within a month. We analyzed data from 694 CRT defibrillator patients who were followed for 11.7 ± 2 months. Ninety patients had 141 adjudicated HF hospitalizations with pulmonary congestion at least 60 days after implantation. Patients with a positive combined HF device diagnostics had a 5.5-fold increased risk of HF hospitalization with pulmonary signs or symptoms within the next month (hazard ratio: 5.5, 95% confidence interval: 3.4 to 8.8, p < 0.0001), and the risk remained high after adjusting for clinical variables (hazard ratio: 4.8, 95% confidence interval: 2.9 to 8.1, p < 0.0001). Monthly review of HF device diagnostic data identifies patients at a higher risk of HF hospitalizations within the subsequent month. (PARTNERS HF: Program to Access and Review Trending Information and Evaluate Correlation to Symptoms in Patients With Heart Failure; NCT00279955).