Positron emission tomography (PET) is indicated for a large number of cardiac diseases: perfusion and viability studies are commonly used to evaluate coronary artery disease; PET can also be used to assess sarcoidosis and endocarditis, as well as to investigate amyloidosis. Furthermore, a hot topic for research is plaque characterization. Most of these studies are technically very challenging. High count rates and short acquisition times characterize perfusion scans while very small targets have to be imaged in inflammation/infection and plaques examinations. Furthermore, cardiac PET suffers from respiratory and cardiac motion blur. Each type of studies has specific requirements from the technical and methodological point of view, thus PET systems with overall high performances are required. Furthermore, in the era of hybrid PET/computed tomography (CT) and PET/Magnetic Resonance Imaging (MRI) systems, the combination of complementary functional and anatomical information can be used to improve diagnosis and prognosis. Moreover, PET images can be qualitatively and quantitatively improved exploiting information from the other modality, using advanced algorithms. In this review we will report the latest technological and methodological innovations for PET cardiac applications, with particular reference to the state of the art of the hybrid PET/CT and PET/MRI. We will also report the most recent advancements in software, from reconstruction algorithms to image processing and analysis programs.