LVH and Arrhythmias
Spectrum and Prognostic Signiﬁcance
of Arrhythmias on Ambulatory Holter
Electrocardiogram in Hypertrophic Cardiomyopathy
A. Selcuk Adabag, MD,* Susan A. Casey, RN,† Michael A. Kuskowski, P
D,* Andrey G. Zenovich, MS
Barry J. Maron, MD, FACC†
OBJECTIVES The goal of this study was to assemble a proﬁle and assess the signiﬁcance of arrhythmias in
a nontertiary-based hypertrophic cardiomyopathy (HCM) cohort.
BACKGROUND Hypertrophic cardiomyopathy is associated with arrhythmia-related consequences, particu-
larly sudden death. Ventricular tachyarrhythmias on Holter electrocardiograms (ECG) have
been reported as markers for sudden death in highly selected HCM populations.
METHODS We assessed the proﬁle of ventricular and supraventricular ectopy and bradyarrhythmia on
ambulatory 24-h Holter ECG and also related these ﬁndings to clinical outcome in 178
RESULTS Of the 178 study patients, 157 (88%) had premature ventricular complexes (PVCs), including
21 (12%) with Ն500 PVCs, 74 (42%) had couplets, 67 (37%) had supraventricular tachycardia
(SVT), and 56 (31%) had nonsustained ventricular tachycardia (NSVT). Mean number of
PVCs was 330 Ϯ 763 (range 1 to 5,435) and increased with age (p Ͻ 0.01); NSVT was
associated with greater left ventricular hypertrophy (p ϭ 0.01) and severe symptoms (New
York Heart Association functional classes III and IV) (p ϭ 0.04); SVT occurred more
commonly in patients with outﬂow obstruction (p ϭ 0.02). Over a follow-up of 5.5 Ϯ 3.4
years, 11 (6%) patients died suddenly (annual mortality rate, 1.1%) including 5 patients with
NSVT. For sudden death, NSVT on Holter ECG had negative and positive predictive values
of 95% and 9%, and sensitivity and speciﬁcity of 45% and 69%, respectively.
CONCLUSIONS In this nontertiary-based HCM cohort, ventricular and supraventricular tachyarrhythmias
were particularly frequent and demonstrated a broad spectrum on ambulatory (Holter) ECG.
Paradoxically, despite such a highly arrhythmogenic substrate, sudden death events proved to
be relatively uncommon. Ventricular tachyarrhythmias had a low positive and relatively high
negative predictive value for sudden death in this HCM population. (J Am Coll Cardiol
2005;45:697–704) © 2005 by the American College of Cardiology Foundation
Hypertrophic cardiomyopathy (HCM) is a primary myo-
cardial disease associated with a risk for sudden death as a
direct consequence of ventricular tachyarrhythmias (1–9).
Indeed, HCM is the most common cause of sudden cardiac
death in young people, including trained athletes (2,10 –18).
Ambulatory Holter electrocardiography (ECG) has been
used extensively in the evaluation and risk stratiﬁcation of
HCM patients (19–24). Previously, in HCM cohorts from
tertiary care centers with a disproportionate representation
of high-risk patients, nonsustained ventricular tachycardia
(NSVT) on 24- to 48-h ambulatory ECG proved to be
predictive of future events (20,21,24). However, arrhythmia
proﬁle (and its prognostic signiﬁcance) in less selected
HCM cohorts that are closest to the true disease state in the
community remains unresolved and is the focus of this
Selection and demographics of study patients. Between
1975 and 2001, 535 patients with HCM were evaluated at
the Minneapolis Heart Institute, a large community-based
clinic and hospital service primarily supporting the Minne-
apolis and St. Paul metropolitan area (population, 3 million)
and the state of Minnesota (population, 5 million) (2– 4).
Of these, 296 patients from the ﬁve-state Upper Midwest
region (Minnesota and the contiguous states of Wisconsin,
Iowa, North Dakota, and South Dakota), not subject to
tertiary center referral, were initially included in the study
group. None of these patients had been selectively referred
to our institution for specialized care of HCM. The other
239 HCM patients evaluated at our institution since 1994,
who were preferentially referred to the senior author
(B.J.M.) for specialized care related to HCM (in the context
of tertiary referral) were excluded from the present cohort.
Patients in this study were initially referred for cardiac
symptoms (e.g., dyspnea or chest pain), ﬁndings on physical
examination (e.g., heart murmur), abnormal ECG, evalua-
tion of other cardiac diseases (e.g., coronary artery disease), or
acute cardiovascular events (e.g., syncope, atrial ﬁbrillation).
From *Division of Cardiology, and Geriatric Research Education and Clinical
Center, Veterans Affairs Medical Center, Minneapolis, Minnesota; and the †Hyper-
trophic Cardiomyopathy Center, Minneapolis Heart Institute Foundation, Minne-
Manuscript received June 27, 2004; revised manuscript received November 12,
2004, accepted November 16, 2004.
Journal of the American College of Cardiology Vol. 45, No. 5, 2005
© 2005 by the American College of Cardiology Foundation ISSN 0735-1097/05/$30.00
Published by Elsevier Inc. doi:10.1016/j.jacc.2004.11.043