4 research outputs found
Coefficient of RâR interval variations under deep breathing load in patients with wildâtype transthyretin amyloid cardiomyopathy: A caseâcontrol study
Abstract Background and Aims An autonomic nervous disorder is an important characteristic of cardiac amyloidosis; however, the prevalence of autonomic dysfunction in wildâtype transthyretin amyloidosis (ATTRwt) has not been established. Analysis of the RâR interval coefficient of variation (CVRâR) is a noninvasive method to measure parasympathetic activity. We aimed to assess autonomic dysfunction of ATTRwt and determine the utility of CVRâR for the detection of ATTRwt in other cardiac diseases. Methods This is a singleâcenter, retrospective, caseâcontrol study. Fifty patients with heart failure (HF) were studied. The etiologies of HF were as follows: ATTRwt, nâ=â10; previous myocardial infarction (MI), nâ=â20; and left ventricular hypertrophy (LVH) due to other disease processes (e.g., aortic stenosis), nâ=â20. We measured the CVRâR at rest (CVRâRrest), CVRâR with deep breaths (CVRâRbreath), and the change rate (CVRâRdiff rate). The relative change formula is as follows: CVRâRdiff rateâ=â(CVRâRbreathâââCVRâRrest)/CVRâRrestĂ â100 (%). Results There was no difference in the CVRâRrest levels among the three groups. The CVRâRdiff rate levels in the ATTRwt group were significantly lower (ATTRwt: â8.77 [â43.8 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 ATTRwt in HF, the best cutâoff value for the CVRâRdiff rate was 19.7 (area under the curve: 0.848). Conclusion Our data suggested autonomic dysfunction in patients with ATTRwt. Measurement of the CVRâR in HF patients may be a convenient support tool for the detection of ATTRwt