3
6. In addition to established indications, pacemaker implantation or,
in selected individuals, pacing-capable implantable cardioverter-
defibrillator (ICD) placement is indicated in patients with myotonic
dystrophy type 1 (DM1) or type 2 (DM2) who have evidence of
abnormal atrioventricular (AV) conduction, marked by PR interval
≥240 ms, QRS duration ≥120 ms, and/or HV interval ≥70 ms, even
when asymptomatic.
7. Patients with Emery-Dreifuss muscular dystrophy (EDMD) or limb-
girdle muscular dystrophy type 1B (LGMD1B) with abnormal AV
conduction, including PR interval ≥230 ms, or HV interval ≥70 ms,
are at higher risk of arrhythmic events including sudden death,
even when asymptomatic. Transvenous (or equivalent pacing-
capable) ICD placement is indicated in such patients.
8. Patients with mitochondrial myopathies, such as Kearns-Sayre
syndrome, are susceptible to developing advanced, distal
conduction disease. Pacemaker implantation is indicated in these
patients who demonstrate AV conduction abnormalities, particularly
if progressive, including fascicular block.
9. Initiation of oral anticoagulation in patients with NMDs who
develop atrial fibrillation (AF) should be based on established risk
criteria (e.g., CHA
2
DS
2
-VASc, HAS-BLED in adults). Individuals
with EDMD or LGMD1B and AF should be treated with oral
anticoagulation regardless of CHA
2
DS
2
-VASc score because of the
association with atrial standstill and suspected heightened risk of
thromboembolism.
10. Early but limited experience with gene modification in some
heritable diseases has been promising and is now being employed
in patients with NMDs. The hope for additional advances must be
tempered by the complexity of these therapeutics and the small
number of patients with NMDs who qualify for such treatment.
