Nuclear cardiology came of age in the 1970s and subsequently has expanded so that more than 9 million single-photon emission computed tomography (SPECT) studies are performed annually in North America. Coronary artery disease management has demanded a reliable technique that will detect, risk stratify, and assist with revascularization decisions. Using cardiac SPECT and positron-emission tomography (PET), researchers and clinicians have sought to achieve excellence in coronary artery disease diagnosis and risk stratification, and strive to achieve higher standards in these areas. Developments in other cardiac imaging modalities, however, such as cardiac computed tomography, cardiac magnetic resonance, and echocardiography, have raised expectations in terms of diagnostic accuracy and achieving high quality images with little or no ionizing radiation exposure. The challenge facing nuclear cardiology as it embarks upon a fifth decade of clinical use is whether high quality images can be obtained at lower radiation exposures. In this review we consider current practice in SPECT and PET perfusion imaging. We discuss emerging advances in techniques, technologies, and radiotracers that focus specifically on improvements in image quality that enhance diagnostic accuracy while reducing radiation exposure. We provide a perspective as to the future roles of cardiac SPECT and PET in ischemic heart disease, and consider emerging novel applications beyond perfusion imaging. Although for a number of years nuclear cardiology has shone brightly as a leading light for the imaging of ischemic heart disease, its half-life has not yet been reached. Instead, even with the pressure to reduce radiation exposure, the future continues to look bright for cardiac SPECT and PET.