103CHANGING PROFILE OF YOUNG PATIENTS WITHHYPERTROPHIC CARDIOMYOPATHY RECEIVING IMPLANTABLECARDIOVERTER DEFIBRILLATORS

S Abadir, M Shah, AM Dubin, RM Hamilton, NJ Kertesz,JC Perry, CI Berul, EP Walsh, F Cecchin

Montréal, Québec

BACKGROUND: Implantable cardioverter defibrillator (ICD)therapy is increasingly -utilized for prevention of suddencardiac death (SCD) in young patients with hypertrophiccardiomyopathy. The indications and ICD technology havechanged significantly over the past 20 years, with downsizedgenerators and leads more suitable for smaller patients.OBJECTIVE: Describe changes in pattern of implant indicationsand appropriate therapies during the last two decades in youngHCM patients.METHODS: Multicenter and retrospective review of youngHCM patients who underwent ICD implant for HCM.RESULTS: 120 HCM patients � 21 years of age (14.2 years[0.9-21.8]) who underwent ICD implant between 1990 and2010 were included. During a median follow up of 2.4 years(0.1-13.4), 7 patients died and 7 underwent heart transplant.Appropriate and inappropriate therapies were delivered in33/120 patients (28%) and 37/120 (31%), respectively.Freedom from appropriate shocks at 2, 4 and 6 years was37%, 19% and 19% for secondary prevention patients(n¼24) compared to 84%, 72% and 63% for primary pre-vention patients (n¼96). Patients were divided according todecade of ICD implant date ([1990-2000] and [2001-2010]). Secondary prevention indications decreased betweenthe two decades (34% vs 12%, p<0.01). For primary pre-vention patients, time from diagnosis to implant was longer(4.2 vs 1.8 yrs, p¼0.02) and age at implant was older (14.3vs 12.6 yrs, p¼0.04) in the recent era compared to the olderera. This occurred despite similar SCD risk profiles usingclassic risk factors (p¼0.7). Time to first appropriate shockfor primary prevention patients was shorter in the earlier era(p¼0.04).CONCLUSION: Over the last 20 years, ICD implant in youngHCM patients for primary prevention has increased. Riskscores are comparable between both decades, suggesting anincrease in number of patients referred for primary preventionICD implant rather than broadening of indications.

104FINDINGS IN RELATIVES OF VICTIMS OF SUDDENUNEXPLAINED DEATH

IA Al Abri

Edmonton, Alberta

PURPOSE: To review findings in close relatives of victims ofsudden unexplained death (SUD) with “undetermined causeof death” or newly identified cardiomyopathy.METHOD: Medical examiners advised families of victims ofSUD to contact our cardiology clinic for evaluation.

RESULTS: Between March 2010 and October 2013, medicalexaminers identified 27 SUD victims probably resulting fromcardiac arrhythmia (17 male, age 2 - 64, mean 38 years, 5under 18 years) with unrevealing autopsy results (16), RVcardiomyopathy (8) and LV cardiomyopathy (3).

Families of 15 deceased (10 male, age 2 - 52, mean 31years, 5 under 18 years) sought clinical evaluation. Fourdeceased collapsed with exertion (3 unrevealing autopsy, 1 RVcardiomyopathy) and 11 died in sleep or at rest (6 unrevealingautopsy, 3 RV cardiomyopathy, 2 LV cardiomyopathy).Subsequently, 33 family members (8 males, age 0.2 - 67,mean 27 years, 11 under 18 years, 31 first degree relatives)were evaluated in the clinic with diagnostic tests appropriatefor suspected familial disorder. One 64 year old woman wasdiagnosed with hypertrophic cardiomyopathy; autopsy in a 39year old son showed hypertrophic cardiomyopathy. Two pa-tients had borderline QT intervals of less than 500 ms and 2had frequent premature ventricular beats (“undeterminedcause of death” in the related deceased). One patient had mildsegmental left ventricular dysfunction by MRI (RV cardio-myopathy in the deceased brother).CONCLUSION: Clinical evaluation of SUD victims’ relativesreferred by medical examiners is effective in diagnosingarrhythmogenic conditions in other family members.

105ELECTROCARDIOGRAPHIC DATA AND RHYTMIC EVENTS IN APEDIATRIC COHORT OF MYOTONIC DYSTROPHY 1: A LONGTERM FOLLOW-UP STUDY

N Malliet, N Dahdah, P Khairy, L Rivard, M Talajic, A Fournier

Montréal, Québec

BACKGROUND: Myotonic dystrophy (MD1) is an inheritedmuscular dystrophy responsible for myocardial degenerationof the cardiac conduction system, with a high risk of suddendeaths in adults. Long-term clinical course and ECG findingsin a pediatric cohort have yet to be assessed.METHODS: We retrospectively collected clinical and electro-cardiographic data in patients with proven MD1 followed atour neuromuscular disease center. An arrhythmic event wasdefined as syncope or sudden cardiac death of presumedarrhythmic etiology. PR interval, QRS width, and axial de-viation were compared to standard data described byDavignon et al. and defined as abnormal when values aresuperior to the 98th percentile for PR and QRS durations,and out of the 1st and the 98th percentiles for axial deviation.RESULTS: A total of 56 patients were included with a meanage at diagnosis of 5.3 � 4.9 years and a follow-up duration of7.2 (range 1.9-15.6) years. Of these patients, 27 cases (48.2%)were congenital MD1 with a reported diagnosis in the firstyear of life. At baseline, 21.4 % (n¼12) had PR values su-perior to the 98th percentile and 78.5 % (n¼44) had awidening of QRS. By the end of a follow up, these conductionabnormalities progress with PR prolongation notified in 25.0%, and widening of QRS in 87.5%. Only 12.5 % (n¼7) inthe cohort had normal ECG findings at the end of follow-up.

Abstracts S109

Over the course of follow-up, 5 patients had syncope (meanage 15.1 � 3.7) and 2 patients died suddenly (mean age 17.5� 1.9), corresponding to an event-free survival rate of 98 % at7.2 years. All of these patients had abnormal ECG findingsbut, in univariate analyses, only the width of QRS was asso-ciated with arrhythmic events (110.3 � 8.2 ms in the eventgroup vs. 98.1 � 1.7ms in the no-event group, p¼0.03). 71.4% (n¼5) were diagnosed in their first year of life.CONCLUSION: During a follow up nearly 16 years, more than85% of pediatric patients who suffered from MD1 had ECGabnormalities, which increased over time. Rhythmic events inpediatric population are rare but exist, and occured in patientswith conduction abnormalities on basal ECG.

106PREMATURE VENTRICULAR CONTRACTIONS IN HEALTHYCHILDREN: DOES THE BURDEN OF ECTOPY MATTER?

S Abadir, CG Blanchet, N Dahdah, W Mawad, P Khairy,A Fournier

Montréal, Québec

BACKGROUND: Premature ventricular contractions (PVCs) area common finding in healthy children. Whereas a burden ofventricular ectopy higher than 20% in adults with normalhearts was found to increase the risk of cardiovascular eventsand LV dysfunction, there is little knowledge about theconsequences of frequent PVCs diagnosed in a healthy child.METHODS/RESULTS: We reviewed 24h-Holters performed be-tween 2008 and 2012 at our institution, and identified patientswith structurally normal hearts (or with minimal non-signifi-cant structural abnormalities) and a burden of PVCs� 10% oftotal beats on any Holter during follow-up. Demographic datawere collected and trans-thoracic echocardiography (TTE),ECG and 24h-Holters at each evaluation were reviewed.

A total of 47 patients (22 female; mean age 8.2�6.5 y) had19.2 � 10.3% PVCs recorded on initial 24h-Holter. Leftbundle branch morphology was dominant in 33/45 (73%).No evidence of severe cardiomyopathy was found on initialTTE with mean shortening fraction (SF) Z-score of 0.1�2.0.Yet, 7 patients (14.9%) had decreased SF (Z-score: -2.4 to -4).On initial ECG, mean PVC coupling interval was431.9�110.5ms, and mean PVC width was118.6�27.1msec; runs of non-sustained or sustained ven-tricular tachycardia (VT) were present in 3 (6.4%) patients.On 24h-Holter, PVCs were monomorphic in 44/47 (93.6%),ventricular bigeminy was recorded in 26.9� 29.2% of thetotal PVC time in 37/47 (78.7%) patients. SF Z-score wasworse in cases with shortest coupling interval and with higher24-hour PVC proportion (figure 1). A similar trend was notedbetween the percentage of ventricular bigeminy and SF Z-score. During follow-up (3.9�2.3 yrs) no death occurred, anda significant decrease in PVC burden was observed (from 19.2� 10.3% to 7.7�11.1%; p<0.001) coupled with a trendtowards improved systolic function (SF Z-score from0.11�2.04 to 0.69�1.9; p¼0.11). Three patients withfrequent and sustained runs of VT underwent successful PVC

ablation. On final Holter follow-up, 19/47 (40%) patientshad <1% PVCs.CONCLUSION: PVCs seem to be a benign finding in childrenwith structurally normal hearts, with no reported death or severecardiomyopathy in this small series. Yet, mild LV systolicdysfunction is observed in some patients, correlating with ahigher burden of ectopy. Spontaneous resolution occurs inmostcases. Larger series are needed to confirm these findings, andestablish recommendations regarding potential treatment, andfrequency of follow up. Figure Legend: Relationship betweenPVC burden (24-hour PVC%) and coupling interval (mSec) onnormalized left ventricular shortening fraction (Z-score).

107NT-PRO BNP AFTER FONTAN ANASTOMOSIS: EARLY VERSUSLATE POST-OPERATIVE VALUE

A Fournier, J Selly, N Dahdah

Montréal, Québec

BACKGROUND: NT- proBNP has become a marker for thediagnosis aiding prognosis and therapeutic guidance of cardiacconditions in adults. However, its assessment remains limitedin congenital cardiology, particularly in patients with uni-ventricular heart physiology who underwent total cav-opulmonary connection (TCPC) where long-term prognosisis greatly related to ventricular function.

The aim of this study was to evaluate the NT- proBNPserum level after TCPC and seek a possible correlation withclinical and laboratory monitoring.METHODS: A retrospective study was initiated on all TCPCpatients born after 1991. Demographic, anatomical andechocradiography data were collected for all subjects followingthe early post-operative period. Routine biochemical dataincluding NT-proBNP were similarly collected. Routine NT-proBNP screening for these patients was initiated in ourinstitution in 2008. NT-proBNP z -score was calculated basedon our published equation from healthy children.RESULTS: Of a total of 46 patients who completed TCPC, 5died post-operatively. All remaining 41 subjects had availableNT-proBNP beyond the immediate post operative period andconstituted the study population. Mean TCPC age was4.8�1.1 years, with a mean follow-up of 6.24�5.0 years.Serum NT-proBNP level was significantly elevated during thefirst post-operative year (Z-score 1.9�1.17) compared to mid-term follow-up (3-5 years) (Z-score 1.23�0.72), p ¼ 0.03.Mean NT-proBNP Z-score increased in the subsequent yearsto 1.6�1.1 (p ¼ 0.21 v.s. year-1 post TCPC, and 0.06 v.s.mid-term). Z-scores > 2.0 were associated with a lower serumalbumin (39.2�3.3 v.s. 44.4�4.4 mg/dl; p¼0.04), but notwith other laboratory tests. There were however no identifi-able predisposing clinical factors (i.e., ventricular morphology,age), preoperative hemodynamic data (e.g., PVRi, mean pul-monary artery pressure, Nakata index), surgical specifics (typeof TCPC, presence of fenestration, pacemaker implantation),or postoperative events.

S110 Canadian Journal of CardiologyVolume 30 2014