Only few studies aimed at identifying predictors of heart failure (HF) in hypertrophic cardiomyopathy (HC) patients. Furthermore, serial echocardiographic analyses are lacking in these patients and little is known about the natural progression of left ventricular (LV) abnormalities and their association with HF development. Aim of this study was to assess the prognostic value of LV global longitudinal strain (GLS) and other clinical and echocardiographic characteristics for the development of HF in patients with nonobstructive HC; furthermore, changes in echocardiographic parameters over time were correlated with HF development. Echocardiography was performed in 236 HC patients (68% men, age: 50 ± 14 years) at their initial visit and during follow-up (6.5(4.1 to 9.8) years). The end point of new HF development or progression to New York Heart Association class III/IV was noted and echocardiographic changes over time were compared among patients with and without HF using linear mixed model analysis. In total, 40 patients reached the HF end point. Multivariable cox regression analysis showed that age (HR 1.04(1.01 to 1.06), p = 0.016), New York Heart Association class (HR 2.30(1.07 to 4.95), p = 0.033), GLS (HR 1.15(1.05 to 1.22), p = 0.001), and left atrial volume (LAVI, HR 2.22(1.10 to 4.50), p = 0.027) were independently associated with the HF end point. Echocardiographic parameters, including GLS and LAVI, remained stable over time in patients without HF end point, but changed significantly in patients who developed HF (group-time interaction, p = 0.042 for GLS and p = 0.027 for LAVI). In conclusion, LV dysfunction is a progressive phenomenon in nonobstructive HC patients which can be detected by repeated echocardiography. Importantly, GLS and LAVI at baseline as well as their changes over time are associated with HF.