Identification of the problem, procedures, techniques and patient management: In 2013, the CKD stage four patient due to chronic allograft dysfunction had his first MPI SPECT scan. This test revealed reversible defects indicating mild ischemia of the inferior/inferolateral cardiac wall and part of the myocardial apex. While the patient being asymptomatic, successive MPI SPECT performed in years 2013, 2014, 2016 and 2017 (Fig A, a: 2013; b: 2014; c: 2016; d: 2017), demonstrated progressively established ischemia partially reversible at rest. Due to deteriorating MPI SPECT images, a coronary angiogram was performed in 2017, which failed to reveal any hemodynamically significant coronary stenoses (Fig B). Consistent with the MPI SPECT results was obtained by echocardiography which demonstrated a deteriorating hypokinesia of the left ventricular wall in the yearly examinations.
Questions, problems or possible differential diagnosis: Both two imaging methods (MPI and U/S), verified the existence of myocardial ischemia in this patient ruling out an artifactual phenomenon. This raised the question why this patient did not have CAD. Was it due to a reversible vasoconstrictive mechanism? Should such patients be subjected to MPI screening tests? And if so, could these patients have any preventive therapeutic interventions? The images emphasize the value of MPI to detect myocardial ischemia possibly due to irregular vasoconstrictor/vasodilatory coronary capability. In fact, scientific evidence suggests that renalase, a flavin adenine dinucleotide-dependent amine oxidase is increased during CKD, metabolizes catecholamines and may increase the levels of circulating endothelin-1, a potent vasoconstrictor. Thus, episodes of reversible coronary vasoconstriction may result in myocardial ischemia without obvious coronary stenoses.
Conclusions and implications for clinical practice: Patients with CKD are in high risk for myocardial ischemia and should be screened routinely with several imaging methods, especially with MPI, an imaging that can provide crucial information about the cellular myocardial status. Irregular vasoconstrictor/vasodilatory coronary capability can be a risk factor for ischemia in this group of patients, independent of the existence or not of CAD.