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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. 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

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  1. Sudden Cardiac Death in Structurally Normal Heart Brian D. Le, MD Presbyterian Hospital CIVA

  2. 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

  3. A- 35 yo WM c syncope • B- 31 yo sister, dizziness and palpitations • C- 6 yo son, SCD

  4. 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.

  5. 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.

  6. 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

  7. Brugada’s

  8. Catecholaminergic Polymorphic VT

  9. Idiopathic VF

  10. A- 35 yo WM c syncope • B- 31 yo sister, dizziness and palpitations • C- 6 yo son, SCD

  11. Evaluation • Physical Exam • Serial ECG’s • Holter • Heart rate variability • QT dispersion • Signal-averaged ECG • Echocardiogram • Cardiac MRI • Electrophysiological Study

  12. 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

  13. 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.

  14. 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.

  15. Factors That Shorten QT • Increase in heart rate • Hyperthermia • Hypercalcemia • Hyperkalemia • Acidosis • Changes in autonomic tone

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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.

  21. 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.

  22. Ventricular ERP

  23. 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.

  24. ICD • First line therapy • Risk of inappropriate shock delivery- Tw oversensing (Schimpf et al. JCE. 14: Dec 2003)

  25. - Ventricular ERP- <150ms - induction of VF - Atrial ERP- 120ms Circulation. 2003; 108

  26. Family Tree 49 yo 39 yo 39 yo 8 mo Circulation. 2003; 108

  27. Schimpf, et al. Heart Rhythm. 2004;2

  28. 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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