Cytoplasmic calcium signalling is the principal determinant of contractility within cardiac muscle. Within the junctional membrane complex, clusters of the ryanodine receptor (RyR) are located upon the cell’s internal calcium store. This forms a structural unit, known as a couplon, which mediates intracellular calcium release. We recently reported structural remodelling of RyR cluster pattern within the couplon in right ventricular heart failure (RV HF). At a local level, the functional implication of this structural remodelling is not fully understood. Isolated right ventricular cardiomyocytes were obtained from adult male Wistar rats. Rodents were either injected (intraperitoneal) with monocrotaline (60 mg/kg) to induce pulmonary arterial hypertension which led to compensated RV HF (MCT-RV) or with saline (Ctrl-RV) as previously established (Fowler et al. 2015). Cardiomyocytes from MCT-RV and Ctrl-RV were imaged using the new super-resolution microscopy method, DNA-PAINT, exploiting its ability to resolve single RyR in situ. All results are displayed as mean ±SEM. Remodelling was observed in the form of dispersed RyR array patterns within the peripheral (sub-sarcolemmal) couplons. This was evident by a significant reduction in MCT-RV average peripheral RyR cluster size (MCT-RV 3437±469 nm2; Ctrl-RV 11246±1901 nm2, p<0.05 t-test, n=3). Subsequently, MCT-RV had a significant reduction in RyR density per cluster, with a near halving of RyR per cluster compared to Ctrl-RV (MCT-RV 2.31±0.21 puncta; Ctrl-RV 3.83±0.55 puncta, p<0.05 t-test, n=3). Fragmentation of the near-surface RyR cluster pattern was observed within MCT-RV cardiomyocytes. This was represented by a significantly decreased proximity between an RyR puncta and its three nearest neighbours (MCT-RV 61±0.97 nm; Ctrl-RV 64±0.99 nm, p<0.05 t-test, n=3). Using a correlative imaging protocol, we have examined the functional implication of an altered RyR pattern upon a cardiomyocyte’s local calcium signalling properties. With this, we observe an increased frequency of spontaneous calcium release in the local regions which exhibit a fragmented RyR pattern.