Tests for Early Diagnosis of Cardiovascular Autonomic Neuropathy: Critical Analysis and Relevance

Abstract

INITIAL CONSIDERATIONS Despite its high prevalence in individuals with diabetes mellitus (DM) neuropathies are the most underdiagnosed and undertreated diabetic chronic complication (1). The involvements of somatic and autonomic nerve fibers in DM present complex pathophysiologies (1–4). The impairment of sympathetic and parasympathetic divisions of the autonomic nervous system (ANS) leads to diabetic autonomic neuropathy (DAN), a condition that may affect different organ systems such as cardiovascular, gastrointestinal, genitourinary, sudomotor, and visual (4). Cardiovascular autonomic neuropathy (CAN), within the context of DAN, occurs when there is an impairment of autonomic control of the cardiovascular system after ruling out other causes of dysautonomia (1). It is known that CAN is an early and frequent complication of DM, affecting from 7 to 15% of newly diagnosed patients to 90% of those in line for a double transplant. In addition, CAN is among one of the most disabling complications of DM in terms of life expectancy and quality. Clinical manifestations of CAN are pleomorphic and appear in late stages, and in isolation do not present enough sensitivity and specificity for diagnosis requiring the use of objective autonomic tests (3, 4). Thus, detection of CAN in a diabetic patient requires sensitive and specific tests in order to establish differential diagnosis and quantify the severity of dysautonomia (3). Specifically, the presence of symptoms or signs suggestive of autonomic changes – such as erectile dysfunction, dizziness, intermittent visual impairment, postprandial hypotension, resting tachycardia, or exercise intolerance (dyspnea) in persons with DM – should be investigated and confirmed by performing objective diagnostic tests for CAN (3, 4).