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Sudden Cardiac Death in Structurally Normal Heart. Brian D. Le, MD Presbyterian Hospital CIVA. Presentation. HPI -35 yo WM s PMH presents with exertional syncope h/o PAF since 18 yrs of age Holter- monomorphic isolated PVC’s Echo- structurally normal heart Meds - no OTC or herbal

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sudden cardiac death in structurally normal heart

Sudden Cardiac Death in Structurally Normal Heart

Brian D. Le, MD

Presbyterian Hospital

CIVA

presentation
Presentation
  • HPI-35 yo WM s PMH presents with exertional syncope
    • h/o PAF since 18 yrs of age
    • Holter- monomorphic isolated PVC’s
    • Echo- structurally normal heart
  • Meds- no OTC or herbal
  • Social- occ. Etoh, no IVDA
  • Family History
    • Sister (31) - dizziness and palpitations
    • Sister’s son (6) - cardiac arrest at 8 mo old after a loud noise with successful DCCV

Gaita et al. Circulation. 2003; 108

slide3
A- 35 yo WM c syncope
  • B- 31 yo sister, dizziness and palpitations
  • C- 6 yo son, SCD
sudden cardiac death
Sudden Cardiac Death
  • “Unexpected death from cardiac cause within a short time (~1 hour of sx) in a person without prior conditions that would appear fatal.”
  • 300-400,000 deaths annually (U.S.).
  • VT/VF account for 80%.
  • 20% have structurally normal hearts.

Wever E, et al. JACC. Vol 43, 2004.

sudden cardiac death5
Sudden Cardiac Death
  • Normal hearts, < 40 years old
  • < 30% successful resuscitation reaching hospital
  • Risk of life-threatening events in cardiac arrest survivors is 25-40% at two years

Wever E, et al. JACC. Vol 43, 2004.

primary electrophysiologic abnormalities
Primary Electrophysiologic Abnormalities
  • WPW: anterograde BPT ERP <250ms.
  • Brugada: RBBB w/ST elevation V1-V3
  • Catecholamine Polymorphic VT: hRyR2.
  • Long QT: QTc (>440ms), TdP w/long coupled PVC (600-800ms).
  • Short-coupled TdP: normal QTc, PVC w/short coupling (200-300ms).
  • Short QT syndrome
  • Idiopathic VF
slide10
A- 35 yo WM c syncope
  • B- 31 yo sister, dizziness and palpitations
  • C- 6 yo son, SCD
evaluation
Evaluation
  • Physical Exam
  • Serial ECG’s
  • Holter
  • Heart rate variability
  • QT dispersion
  • Signal-averaged ECG
  • Echocardiogram
  • Cardiac MRI
  • Electrophysiological Study
qt interval
QT Interval
  • Represents ventricular repolarization.
  • Normal QTc upper limit: 440ms.
  • Bazett’s formula: QTc = QT/ RR
  • Rautaharju formula (14,379 pts):
    • QTp (ms)= 656/ (1+HR/100)
    • QT/QTp x 100% = % QTpredicted.
    • 88% of QTp = 2 SD below mean
    • Lower limit of nl QT int. = 88% of QTp
qt interval and scd
QT Interval and SCD
  • Algra et al. Br.Ht.J. 1993;70:43-8.
    • Nested cohort 6693 consecutive pts w/24 ECG.
    • F/U 2.5 years in 99.5% of pts.
    • End point: QTc correlation w/SCD (104 pts).
    • Results:
      • QTc >= 440ms  2.3 RR of SCD.
      • QTc < 400ms  2.4 RR of SCD.
familial short qt
Familial Short QT
  • Gussak et al. Cardiology 2000;94:99-102.
    • 3 members of one family; age 17-51 yo.
    • Palpitations, sx PAF, syncopeSCD
    • All w/ structurally normal hearts.
    • All w/ S-QT (260-280ms); QT interval <80% predicted by Rautaharju method.
factors that shorten qt
Factors That Shorten QT
  • Increase in heart rate
  • Hyperthermia
  • Hypercalcemia
  • Hyperkalemia
  • Acidosis
  • Changes in autonomic tone
genetic basis of short qt
Genetic Basis of Short QT
  • Brugada, Antzelevitch, et al. Circ. 2004;109:30-5.
    • Different missense mutations in same residue codon 588 of KCNH2 (HERG [IKr]).
    • Mutations only seen in sQT, and not in normal relatives.
    • Patch clamp models
heterogeneity of short qt
Heterogeneity of Short QT
  • Genetic Studies- KCNQ1 gene mutation G for C, subs. valine for leucine (IKs)
  • Mutations negative in 200 unrelated controlled individuals
  • Loss of function leadsLQT1

Bellocq et al. Circulation. 109; 2004

slide18
KCNJ2, encoding for inwardly rectifying K channel Kir2.1
  • Rapid repolarization
  • SQT3
  • Loss of function results in LQT7 (Anderson’s disease)

Priori et al. Circ. Res. 2005; 96

ion channel mutations
Loss of Function

SCN5A  Brugada

IKs  LQT1

IKr  LQT2

Gain of Function

SCN5A  LQT3

IKs  Fam. A. Fib., Short QT

IKr  Short QT

1

2

Ca > Na

3

0

Na

IKr & IKs

4

Ion Channel Mutations
short qt syndrome rx
Short QT Syndrome Rx
  • Gaita et al. JACC. 2004;43:1494-9.
    • 6 pts. from 2 different families.
    • Drugs: Flecainide (IV or oral), Sotalol, Ibutilide, and Hydroquinidine.
short qt rx results
Short QT Rx Results
  • Flecainide: slight inc. QT due to QRS prolongation.
  • Ibutilide & Sotalol: no change in QT
  • Hydroquinidine:
    • 5/6 pts- QTc normalized (290405ms)
    • EPS 5/5 pts- inc. VERP, no VF/VT
    • F/U 11 mos- 4/6 on hydroquinidine w/o sx or arrhythmias detected by ICD.
quinidine
Quinidine
  • VW Class: Ia (sodium channel blocker)
  • Blocks: INa, IKr, IKs, Ito, L-type Ca2+, IK1(in.rect.), & IKATP  QT increase.
  • Adverse effects: diarrhea, SLE, thrombocytopenia, hepatitis, cinchonism (tinnitus/HA), TdP, many drug interactions 2/2 block of CYP2D6.
slide25
ICD
  • First line therapy
  • Risk of inappropriate shock delivery- Tw oversensing (Schimpf et al. JCE. 14: Dec 2003)
slide26
- Ventricular ERP- <150ms - induction of VF

- Atrial ERP- 120ms

Circulation. 2003; 108

family tree
Family Tree

49 yo

39 yo

39 yo

8 mo

Circulation. 2003; 108

summary short qt syndrome
SummaryShort QT Syndrome
  • Significantly short QTc <= 300ms.
  • Tall & peaked T-waves.
  • Clinical: palpitations, syncope, SCD.
  • Significant FHX of SCD.
  • Atrial and ventricular arrhythmias.
  • Structurally normal hearts.
  • Treatment: ICD and/or Quinidine.
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