APPENDIX
Methodology Details
TFC 2010 Definition of Pathogenic Mutation
A DNA alteration associated with ARVC that alters or is expected to alter the encoded protein, is
unobserved or rare in a large non-ARVC control population, and either alters or is predicted to
alter the structure or function of the protein or has demonstrated linkage to the disease phenotype
in a conclusive pedigree.
Exercise Treadmill Test
12 lead ECGs were obtained during an ETT using the Bruce or modified Bruce protocol.
Deidentified tracings of asymptomatic ARVC gene carriers and healthy controls were analyzed
by 2 observers in 2 of the inherited arrhythmia centers (4 total). Blinding was complete for all
observers in analysis of control ETT tracings; blinding was complete for 3 of 4 observers in
analysis of asymptomatic ARVC tracings. The presence or absence of each depolarization or
repolarization abnormality was reached by mutual consensus where initial observations differed.
Epsilon waves were defined as consistent, low-amplitude deflections in the ST segment and
distinct from the QRS wave. Due to the electrical noise associated with exercise, epsilon waves
were diagnosed only if visualized during the recovery period of the ETT. Epsilon waves had to
be present in 3 or more consecutive QRS complexes in V1 or V2. For exercise treadmill paper
tracings, the 1 minute and 3 minute recovery ECGs were enlarged up to 4 times for inspection.
For electronic exercise treadmill tracings, the tracings were zoomed up to 4 times. Epsilon waves
were not diagnosed in the presence of RBBB.
A PVC was considered to be superior axis when it was of negative polarity in the inferior ECG
leads (leads II, III, and aVF) or was deeply negative in lead V6 (i.e. rS or QS pattern) when the
inferior lead morphology was not available. A PVC was considered of inferior axis when it was
of positive polarity in the inferior leads. An indeterminate axis was assigned when inferior leads
showed discordant polarities, or the axis could not be determined. PVCs were classified as left
bundle branch block (LBBB) morphology when the QRS polarity was predominantly negative in
V1, and RBBB morphology when the QRS polarity was predominantly positive in V1. PVCs
that were not recorded in lead V1 were considered of indeterminate morphology.
TAD was measured from the nadir of the S wave to the end of all depolarization (including
epsilon waves if present) in the ECG lead V1 or V2) (9). TAD was measured at rest, during early
exercise when the heart rate reached 100 beats per minute, and in the recovery period; the
longest measurement was recorded. To improve accuracy of this difficult measure, paper records
were enlarged up to 4x before manual caliper measurement and electronic records (the majority
of tracings) were zoomed up to 4x before electronic caliper measurement. Patients with resting
RBBB were excluded from this analysis in agreement with the Task Force 2010 document
(Supplemental Table 1) (2).
Signal Averaged ECG
Time domain analysis was obtained in the bandpass filter 40-250 Hz. The following parameters
were examined: filtered QRS duration (fQRS), high-frequency low-amplitude duration (HFLA),
and root mean square of the recorded voltage in the last 40 ms of the filtered QRS (RMS40).
Abnormal findings were defined according to TFC 2010 Supplemental Table 1(2)– fQRS ≥ 114
ms, HFLA ≥ 38 ms, RMS40 ≤ 20 µV, in the absence of a resting QRS duration ≥ 110 ms on the
standard ECG. Patients with resting QRS duration ≥ 110 ms were excluded from analysis.
24-hour Holter Recording
The 24-hour Holter recording of each subject was reviewed for total PVC count, ventricular
couplets or triplets.
Cardiac Magnetic Resonance Imaging and Transthoracic Echocardiography
Cardiac MRI and TTE studies were classified as normal or with evidence of minor or major
criteria for ARVC, according to the Revised TFC 2010 (Supplemental Table 1) (2).
Table 1: Revised Task Force Criteria for ARVC 2010
Revised Task Force Criteria for ARVC (2010)
I
Global or regional dysfunction and structural alterations
Major
By 2D echo:


Regional RV akinesia, dyskinesia, or aneurysm
and 1 of the following (end diastole):
 PLAX RVOT ≥ 32 mm (corrected for body size [PLAX/BSA] ≥ 19
mm/m2)
 PSAX RVOT ≥ 36 mm (corrected for body size [PSAX/BSA] ≥ 21
mm/m2)
 or fractional area change ≤ 33%
By MRI:


Regional RV akinesia or dyskinesia or dyssynchronous RV contraction
and 1 of the following:
 Ratio of RV end-diastolic volume to BSA ≥ 110 mL/m2 (male) or ≥
100 mL/m2 (female)
 or RV ejection fraction ≤ 40%
By RV angiography:

Regional RV akinesia, dyskinesia, or aneurysm
Minor
By 2D echo:


Regional RV akinesia or dyskinesia
and 1 of the following (end diastole):
 PLAX RVOT ≥ 29 to <32 mm (corrected for body size
[PLAX/BSA] ≥ 16 to <19 mm/m2)
 PSAX RVOT ≥ 32 to <36 mm (corrected for body size [PSAX/BSA]
≥ 18 to <21 mm/m2)
 or fractional area change >33% to ≤ 40%
By MRI:


Regional RV akinesia or dyskinesia or dyssynchronous RV contraction
and 1 of the following:
 Ratio of RV end-diastolic volume to BSA ≥ 100 to <110 mL/m2
II
(male) or ≥ 90 to <100 mL/m2 (female)
 or RV ejection fraction >40% to ≤ 45%
Tissue Characterization of Wall
Major

Residual myocytes <60% by morphometric analysis (or <50% if estimated),
with fibrous replacement of the RV free wall myocardium in ≥1 sample,
with or without fatty replacement of tissue on endomyocardial biopsy
Minor

III
Residual myocytes 60% to 75% by morphometric analysis (or 50% to 65%
if estimated), with fibrous replacement of the RV free wall myocardium in ≥
1 sample, with or without fatty replacement of tissue on endomyocardial
biopsy
Repolarization abnormalities
Major

Inverted T waves in right precordial leads (V1-V3) or beyond in individuals
> 14 years of age (in the absence of RBBB)
Minor

IV
Inverted T waves in leads V1 and V2 in individuals > 14 years of age (in the
absence of RBBB) or in V4-V6
 Inverted T waves in leads V1-V4 in individuals > 14 years of age in the
presence of RBBB
Depolarization/conduction abnormalities
Major
 Epsilon wave in the right precordial leads (V1-V3)
Minor


Late potentials by SAECG in ≥ 1 of 3 parameters in the absence of a QRS
duration of ≥ 110 ms on the standard ECG
 filtered QRS duration (fQRS) ≥ 114 ms
 duration of terminal QRS < 40 µV (low-amplitude signal duration) ≥
38 ms
 root-mean-square voltage of terminal 40 ms (≤ 20 µV)
Terminal activation duration of QRS ≥ 55 ms (V1-V3) in the absence of
RBBB
V
Arrhythmias
Major

Nonsustained or sustained ventricular tachycardia of left bundle-branch
morphology with superior axis (negative or indeterminate QRS in leads II,
III, and aVF and positive in lead aVL)
Minor

VI
Nonsustained or sustained ventricular tachycardia of RV outflow
configuration, left bundle-branch block morphology with inferior axis
(positive QRS in leads II, III, and aVF and negative in lead aVL) or
unknown axis
 >500 ventricular extrasystoles per 24 hours (Holter)
Family History
Major



ARVC/D confirmed in a first-degree relative who meets current Task Force
criteria
ARVC/D confirmed pathologically at autopsy or surgery in a first-degree relative
Identification of a pathogenic mutation categorized as associated or probably
associated with ARVC/D in the patient under evaluation
Minor



History of ARVC/D in a first-degree relative in whom it is not possible or
practical to determine whether the family member meets current Task Force
criteria
Premature sudden death (<35 years of age) due to suspected ARVC/D in a
first-degree relative
ARVC/D confirmed pathologically or by current Task Force Criteria in
second-degree relative
Table 2: Modified Hamid Criteria for the Diagnosis of Familial ARVC
ECG
TWI in V1 and V2
TAD ≥ 55 ms
SAECG
Late potentials
Structural
Minor or Major MRI Changes
11 of 47 (23%)
6 of 42 (14%)
2 of 45 (4%)
Arrhythmia
Holter PVC count ≥ 200 or NSVT
11 of 45 (24%)
Total Asymptomatic Patients ≥ 1 Criteria
20 of 47 (43%)
T wave inversion (TWI) in V1 and V2, and Terminal Activation Duration (TAD) ≥ 55 ms were
only measured in those individuals without right bundle branch block. Late potentials on SAECG
were present when ≥ 1 of filtered QRS duration ≥ 114 ms, duration of terminal QRS < 40µV was
≥ 38 ms, root-mean-square voltage of terminal 40 ms was ≤ 20µV, were present in the absence
of QRS duration ≥ 110 ms on the resting ECG. Minor or Major MRI changes were defined
according to the revised Task Force 2010 criteria (Supplemental Table 1). Holter PVC count was
measured over 24 hours. NSVT – non-sustained ventricular tachycardia.