Annual assessment of ECG intervals in patients with myotonic dystrophy type 1 using a mobile 6‑lead ECG device:...

Cardiac involvement occurs in approximately 80% of patients with myotonic dystrophy type 1 (DM1), and annual follow-up with a routine 12‑lead ECG (rECG) is recommended. We assessed a mobile 6‑lead ECG device (mECG) as a triage tool to identify DM1 patients with suspected prolonged ECG intervals, validating the feasibility and accuracy of mECG-derived PQ and QRS intervals against rECG.

This supervised in-clinic proof-of-concept study included 50 patients with DM1 and 50 cardiology patients from the cardiology outpatient clinic. All underwent rECG and mECG during a single routine visit. Agreement was assessed using correlation, intra-class correlation coefficient (ICC), and Bland-Altman analyses.

Median [IQR] age was 56 [40-66] years; 45% were women. mECG-derived PQ and QRS intervals correlated moderately to strongly with rECG (Pearson's r = 0.83 and 0.74; ICC = 0.80 and 0.74). Bland-Altman analyses showed mean differences of -2 ms (PQ) and - 14 ms (QRS). The 95%-sensitivity thresholds for detecting prolonged rECG PQ intervals was 175 ms. Consulting only DM1 patients exceeding these limits would potentially reduce hospital visits by 37%. QRS demonstrated the highest systematic bias.

mECG is feasible in patients with DM1 and provides reliable assessment of PQ intervals. Integrated into annual cardiac follow-up, it could serve as a triage tool, potentially reducing outpatient visits by 37% for DM1. This may become increasingly valuable as novel DM1 therapies expand the population requiring regular cardiac surveillance. QRS triage is unsuitable in its current form.