Selective cardiac neuroadrenergic abnormalities in hypertensive patients with left ventricular hypertrophy

Background. Increased sympathetic drive to the heart might contribute to the development and progression of myocardial damage in hypertensive patients (HTs). This study assessed the possible presence of abnormalities in myocardial uptake of I-123-metaiodobenzylguanidine (MIBG), a marker of sympathetic activity, in HTs with left ventricular hypertrophy (LVH).Methods. Eleven HTs with LVH and 10 matched normotensive controls underwent clinical and laboratory examination, as well as LVH determination by echocardiography. The presence of myocardial ischemia was ruled out by exercise stress testing. Global and regional myocardial uptake of I-123-MIBG was determined in both groups using planar and single proton emission tomography scintigraphy. In addition, thallium-201 (TI-201) myocardial scintigraphy was performed in HTs. The heart/mediastinum (HIM) ratio on planar I-123-MIBG images at different time points was compared between HTs and controls. Moreover, regional cardiac uptake of I-123-MIBG was compared between groups and, within the HTs group, with regional TI-201 uptake.Results. At all study times, the H/M ratio was lower in HTs than in controls (all p < 0.05). A significant reduction in I-123-MIBG uptake in the mid-inferolateral and mid-inferior segments was observed in HTs compared to controls. Also, a significant reduction in 123 I-MIBG uptake compared to TI-210 uptake was observed in non-septal segments of HTs.Conclusions. Cardiac abnormalities in global and regional uptake of I-123-MIBG, as well as impaired I-123-MIBG compared to TI-201 uptake, are present in HTs with LVH. Given the effect of sympathetic nervous system on the heart, these abnormalities might play a role in hypertension-related cardiac damage. (c) 2007 IMSS. Published by Elsevier Inc.