Abstract
BACKGROUND AND AIMS: An autonomic nervous disorder is an important characteristic of cardiac amyloidosis; however, the prevalence of autonomic dysfunction in wild-type transthyretin amyloidosis (ATTR(wt)) has not been established. Analysis of the R-R interval coefficient of variation (CVR-R) is a noninvasive method to measure parasympathetic activity. We aimed to assess autonomic dysfunction of ATTR(wt) and determine the utility of CVR-R for the detection of ATTR(wt) in other cardiac diseases. METHODS: This is a single-center, retrospective, case-control study. Fifty patients with heart failure (HF) were studied. The etiologies of HF were as follows: ATTR(wt), n = 10; previous myocardial infarction (MI), n = 20; and left ventricular hypertrophy (LVH) due to other disease processes (e.g., aortic stenosis), n = 20. We measured the CVR-R at rest (CVR-R(rest)), CVR-R with deep breaths (CVR-R(breath)), and the change rate (CVR-R(diff rate)). The relative change formula is as follows: CVR-R(diff rate) = (CVR-R(breath) - CVR-R(rest))/CVR-R(rest) × 100 (%). RESULTS: There was no difference in the CVR-R(rest) levels among the three groups. The CVR-R(diff rate) levels in the ATTR(wt) group were significantly lower (ATTR(wt): -8.77 [-43.8 to 10.9]; LVH: 67.4 [38.7 to 89.4]; MI: 83.7 [60.4 to 142.9]). Based on the receiver operative characteristic curve analysis to identify ATTR(wt) in HF, the best cut-off value for the CVR-R(diff rate) was 19.7 (area under the curve: 0.848). CONCLUSION: Our data suggested autonomic dysfunction in patients with ATTR(wt). Measurement of the CVR-R in HF patients may be a convenient support tool for the detection of ATTR(wt).