Impact of the number of comorbidities on cardiac sympathetic derangement in patients with reduced ejection fraction heart failure

Introduction: Heart failure (HF) is frequently associated with comorbidities. 123I-metaiodobenzylguanidine (123I-mIBG) imaging constitutes an effective tool to measure cardiac adrenergic innervation and to improve prognostic stratification in HF patients, including the risk of major arrhythmic events. Although comorbidities have been individually associated with reduced cardiac adrenergic innervation, thus suggesting increased arrhythmic risk, very comorbid HF patients seem to be less likely to experience fatal arrhythmias. We evaluated the impact of the number of comorbidities on cardiac adrenergic innervation, assessed through 123I-mIBG imaging, in patients with systolic HF. Methods: Patients with systolic HF underwent clinical examination, transthoracic echocardiography and cardiac 123I-mIBG scintigraphy. The presence of 7 comorbidities/conditions (smoking, chronic obstructive pulmonary disease, diabetes mellitus, peripheral artery disease, atrial fibrillation, chronic ischemic heart disease and chronic kidney disease) was documented in the overall study population. Results: The study population consisted of 269 HF patients with a mean age of 66±11 years, a left ventricular ejection fraction (LVEF) of 31±7%, and 153 (57%) patients presented ≥3 comorbidities. Highly comorbid patients presented a reduced late heart to mediastinum (H/M) ratio, while no significant differences emerged in terms of early H/M ratio and washout rate. Multiple regression analysis revealed that the number of comorbidities was not associated with mIBG parameters of cardiac denervation, which were correlated with age, body mass index and LVEF. Conclusion: In systolic HF patients, the number of comorbidities is not associated with alterations in cardiac adrenergic innervation. These results are consistent with the observation that very comorbid HF patients suffer lower risk of sudden cardiac death.