Myotonic dystrophy type 1 (MD1) is the most common muscular dystrophy of adult life. Cardiac involvement is characterized by disorders of atrioventricular conduction, ventricular arrhythmias, and sudden death. Heart rate turbulence (HRT) is a noninvasive risk predictor in patients affected by ischemic heart disease. The aim of our study is to assess the prognostic value of HRT in MD1 patients.Methods and Results
We performed HRT analysis by 24-hour Holter recording to calculate turbulence onset (TO) and turbulence slope (TS) in 29 MD1 patients (mean age 52 ± 10 years), and in 30 patients (mean age 52 ± 13 years) with frequent ventricular arrhythmias and structurally normal heart (VANH). An electrophysiological study (EPS) tested ventricular arrhythmias inducibility in 22 MD1 patients.Methods and Results
TO was significantly different between MD1 and VANH patients (−1.66 ± 2.04 and −2.98 ± 1.79%, respectively, P 0.01), while no difference was observed in TS between MD1 and VANH patients (11.12 ± 6.46 and 9.12 ± 6 msec/beat, respectively). On EPS, sustained ventricular arrhythmias (SVA) were induced in six MD1 patients. TO was significantly different in inducible MD1 patients (0.88 ± 1.95%), as compared with both noninducible (−2.49 ± 1.43%, P < 0.001) or no eligible to EPS (−1.93 ± 1.63%, P < 0.005) MD1 patients and to VANH patients (−2.98 ± 1.79%, P < 0.001).Conclusions
An impairment of TO, a measure of HRT, suggesting impaired cardiac parasympathetic activity, may be a useful, noninvasive predictor of arrhythmic risk in MD1 patients.