Table 1.

Raw clinical, genetic, and imaging data of our study population.

	Anamnestic data		Genetic test	Neuromuscular assessment			Cardiological assessment					CMR assessment
	Age at onset (y, range)	Age at CMR (y, range)	Length (bp)	MRC	MIRS†	Myotonia	Heart rate (bpm)	PR (ms)	QRS (ms)	QTc (ms)	EF (%)	GCS (%)	SCS (%)	GECV (%)	SECV (%)
Patient 1	35–39	50–54	460	103	4	Absent	71	160	108*	450*	68	−16. 5	−24.0	43.2	39.2
Patient 2	25–29	25–29	630	130	5	Absent	73	140	102*	415	64	−16. 7	−15.6	38.4	37.6
Patient 3	15–19	20–24	300	130	2	Absent	70	233*	102*	439	65	−21. 7	−24.2	27.2	26.9
Patient 4	35–39	40–44	1,000	116	4	Absent	73	142	82	470*	67	−21. 3	−24.4	29.3	30.1
Patient 5	35–39	50–54	320	112	4	Absent	69	225*	138*	447*	52	−14. 0	−17.9	36.8	39.0
Patient 6	20–24	35–39	350	128	2	Absent	65	186	110*	445*	70	−20. 1	−22.5	27.5	29.0
Patient 7	10–14	30–34	680	112	3	Absent∧	69	194	105*	417	56	−20. 5	−20.3	31.1	30.5
Patient 8	10–14	25–29	680	130	2	Absent∧	71	174	112*	410	64	−19. 1	−18.7	32.6	34.1
Patient 9	15–19	35–39	490	126	2	Absent∧	73	144	84	402	56	−13. 9	−14.7	32.3	31.9
Median	20	36	490	126	3	–	71	174	105	439	64	−19.1	−20.3	32.3	31.9
IQR	18–35	29–44	350–680	112–130	2–4	–	69–73	144–194	102–110	415–447	56–67	−20.5 to −16.5	−24.1 to −17.9	29.3–36.8	30.1–37.6
Min-max	14–39	24–53	300–1,000	103–130	2–5	–	65–73	140–233	82–138	402–470	52–70	−21.7 to −13.9	−24.4 to −14.7	27.2–43.2	26.9–39.2

CMR, cardiac magnetic resonance; MRC, medical research council scale; MIRS, muscular impairment rating scale; PR interval normal value <200 ms; QRS duration normal value <100 ms; QTc normal values ≤ 430 ms in female or ≤ 450 ms in male; EF left ventricular ejection fraction normal value >50%; GCS, global circumferential strain; SCS, septal circumferential strain; GECV, global extracellular volume; SECV, septal extracellular volume.

^*values out of the normal range.

^∧patients on mexiletine.

^†indicates that the three patients in our sample who had no symptomps of myotonia but were also under mexiletine (anti-dystonic drug).