BACKGROUND: Exercise training (ExT) improves exercise capacity in chronic heart failure, but the results of home-based training have been variable. We sought the predictors of favorable outcome using a telemonitoring approach. METHODS: Exercise capacity and quality of life (QOL) were assessed in 30 patients (28 men, age 64 +/- 8 years) with symptomatic chronic heart failure and left ventricular ejection fraction < or = 35% (28% +/- 9%) undergoing 8 months of home ExT. Patients were provided with heart rate monitors and exercise diaries after undergoing 4 months of hospital-based ExT. Weekly telephone contact was established and heart rate data were downloaded bimonthly. Changes in peak oxygen consumption per unit time (V*O2) and QOL were compared between the 15 most and 15 least adherent patients defined by the number of hours per week at > 60% maximum heart rate, observed during heart-rate monitoring. RESULTS: Peak V*O2 increased by 26% (P < .001) after 4 months of hospital ExT, but this increase had fallen to 8% (P = .07) at 12 months; only adherent patients (n = 15) showed persistent improvement of peak V*O2 at 12 months (P = .02). Improvement in peak V*O2 at 12 months was associated with baseline peak V*O2 (r = -0.61, P < .001) and hours logged on the heart rate monitor (r = 0.47, P = .01). Quality of life improvements were sustained at 12 months for the Minnesota Living with Heart Failure Questionnaire and Hare-Davis Depression Questionnaire. Nevertheless, QOL improvements achieved during the outpatient program were lost or attenuated at 12 months in nonadherent patients but were maintained in adherent patients. CONCLUSIONS: Telemonitoring is feasible for following adherence to home ExT. Ongoing adherence is critical in obtaining sustained benefit from ExT in heart failure.