Many proven heart failure (HF) therapies decrease N-terminal pro B-type natriuretic peptide (NT-proBNP) values over time, yet some patients have an NT-proBNP >1000 pg/mL following treatment, which is associated with poor outcomes. A total of 151 patients with left ventricular systolic dysfunction were treated with aggressive HF therapy in the ProBNP Outpatient Tailored Chronic Heart Failure (PROTECT) study. Clinical characteristics and NT-proBNP were measured at each visit during 10 months. In this post hoc analysis, biomarker nonresponse was defined as an NT-proBNP >1000 pg/mL and its relationship with echocardiographic and clinical characteristics and outcomes were explored. A risk model predictive of nonresponse was derived and externally validated. A rising NT-proBNP over time was associated with increased cardiovascular event rates while a decreasing NT-proBNP was associated with better clinical outcomes (58.2% vs 27.6%, P=.001). A higher percentage of time in biomarker response was associated with lower event rates (P<.001). Importantly, responders showed improved left ventricular remodeling parameters (all P<.001), while nonresponders did not. A risk model for predicting nonresponse had a C statistic of 0.82 (P<.001) and predicted outcomes well. Using data from the NT-proBNP–Assisted Treatment to Lessen Serial Cardiac Readmissions and Death (BATTLESCARRED) cohort, the risk score was validated for its ability to predict nonresponse (C statistic 0.73, P<.001). Serial changes in NT-proBNP inform risk for adverse outcome and are associated with prognostically meaningful metrics. Prediction of future NT-proBNP nonresponse to HF therapy is possible.