22
Treatment
Table 7. Clinical Sudden Death Risk Factors for Adults and
Children With HCM
Family history
of sudden death
from HCM
Sudden death judged definitively or likely attributable to HCM
in ≥1 first-degree or close relatives who are ≤50 y of age. Close
relatives would generally be second-degree relatives; however,
multiple SCDs in tertiary relatives should also be considered
relevant.
Massive LVH Wall thickness ≥30 mm in any segment within the chamber
by echocardiography or CMR imaging ; consideration for this
morphologic marker is also given to borderline values of ≥28 mm
in individual patients at the discretion of the treating cardiologist.
For pediatric patients with HCM, an absolute or z-score threshold
for wall thickness has not been established; however, a maximal
wall thickness that corresponds to a z-score ≥20 (and >10 in
conjunction with other risk factors) appears reasonable.
Unexplained
syncope
≥1 unexplained episodes involving acute transient loss of
consciousness, judged by history unlikely to be of neurocardiogenic
(vasovagal) etiolog y, not attributable to LVOTO, and especially
when occurring within 6 mo of evaluation (events beyond 5 y in
the past do not appear to have relevance).
HCM with
LV systolic
dysfunction
Systolic dysfunction with EF <50% by echocardiography or CMR
imaging.
LV apical
aneurysm
Apical aneurysm defined as a discrete thin-walled dyskinetic or
akinetic segment with transmural scar or LGE of the most distal
portion of the LV chamber, independent of size. (In children,
apical aneurysm is uncommon, and the risk has not been studied.)
Extensive LGE
on CMR imaging
Extensive LGE, representing replacement fibrosis, either quantified
or estimated by visual inspection, comprising ≥15% of LV mass
(extent of LGE conferring risk has not been defined in children).
NSVT on
ambulatory
monitor
≥3 beats at ≥120 bpm has generally been used in studies. It would
seem most appropriate to place greater weight on NSVT as a risk
marker when runs are frequent (eg, ≥3), longer (eg, ≥10 beats),
or faster (eg, ≥200 bpm) occurring usually over 24 to 48 h of
monitoring. For pediatric patients, a VT rate that exceeds the
baseline sinus rate by >20% is considered significant.
Genotype status Genotype-positive status (ie, harboring a putatively disease-causing
pathogenic/likely pathogenic variant) is associated with higher
SCD risk in pediatric HCM patients.
BPM indicate beats per min; CMR indicates cardiovascular magnetic resonance; ICD,
implantable cardioverter-defibrillator; LGE, late gadolinium enhancement; LV, le
ventricular; LVH, le ventricular hypertrophy; LVOTO, le ventricular outflow tract
obstruction; NSVT, nonsustained ventricular tachycardia; SCD, sudden cardiac death; and
VT, ventricular tachycardia.
