7. OVERVIEW
īVT in coronary artery disease
īVT in Dilated Cardiomyopathy
īBundle Branch Reentrant (BBR) VT
īArrhythmogenic right ventricular dysplasia (ARVD)
īVT in Hypertrophic Cardiomyopathy
īVT long after repair of congenital heart disease
īVT in patients with LV assist devices
8. VT IN CORONARY ARTERY DISEASE
īIncidence of VT varies according to the type of ACS.
īGUSTO- 1 trial: 41,000 patients with STEMI treated with thrombolysis.
ī VT â 3.5%.
īPooled analysis of 4 major trials in patients with UA/NSTEMI:
ī VT- 0.8%.
Al-Khatib SM, Granger CB, Huang Y, et al: Sustained ventricular arrhythmias among patients with acute coronary
no ST-segment elevation: Incidence, predictors, and outcomes. Circulation 2002;106:309.
īClinical presentation â tolerated sustained VT to SCD.
9. īSMVT within first 2 days of MI â 3% of cases
ī Associated with increased in hospital mortality as against those without arrhythmias.
ī Mortality not increased at 1 year in 30 day survivors.
īDuring subacute/ healing phase of MI ( > 2 days)
ī Associated with reduced LVEF and is a predictor of worse prognosis.
ī SMVT within 3 months following MI â 40-50% mortality at 2 years.
ī Predictors of increased mortality-
o Anterior wall MI
o Frequent episodes of sustained and/or nonsustained VT
o Heart failure
o Multivessel coronary disease, particularly in individuals with residual ischemia.
īDuring chronic phase:
ī Median time: 3 years; can first occur upto 10-15 years after MI.
ī Annual mortality : 5 â 15% .
10. MECHANISMS OF VT IN CAD
īAll arrhythmia mechanisms can converge in VT associated with
CAD.
īReentry: VT associated with MI scar.
īAutomaticity: VT arising from ischemic border during acute
ischemia.
īTrigerred activity: VT arising during ischemia due to delayed or
early after depolarization.
11. DURING ACUTE ISCHEMIA
īAcute ischemia activates ATP sensitive K channels causing increase in extracellular
K along with acidosis and hypoxia in cardiac muscle.
īIncreased extracellular K
o greater resting depolarization
o decreased conduction velocity
o shortening of action potential duration
o prolongation of effective refractory period (postrepolarization refractoriness)
īIncrease in extracellular K depolarizes the RMP causing increase in tissue
excitability.
īInjury current flows between ischemic and non ischemic cells at border zone
promoting focal activity in normal tissue.
īPolymorphic VT due to microentry.
ī Single reentrant wavefront splits into multiple wavelets when it enters surrounding
nonischemic tissue (shorter effective refractory period).
12. HEALING PHASES OF MI
ī 95% of these VTs due to reentry.
ī Two conditions essential for reentry:
ī Unidirectional block of conduction.
ī Circuit cycle longer than any of the refractory periods throughout the
cycle.
ī Unidirectional block:
ī Anatomical : discontinuities in ventricular muscle, branching strands of
slow conduction or tissue discontinuation due to gap junction
abnormalities present in the areas of MI scar.
ī Functional : due to dispersion of refractoriness.
13. īThe substrate for VT develops gradually over 2 weeks
following a MI.
ī remains indefinitely once formed.
īTriggers:
o Surges in autonomic tone
o Electrolyte imbalance
o Acute ischemia
o Acute heart failure decompensation
14. CLINICAL PRESENTATION
ī Mild symptoms (palpitations).
ī Symptoms of hypoperfusion (light headedness, altered sensorium, presyncope,
syncope).
ī Exacerbation of angina and heart failure.
ī Sudden collapse.
ī Hemodynamic consequences depend on:
o Ventricular rate
o Duration of VT
o Presence and extent of LV dysfunction
o Loss of atrioventricular synchrony
15. ECG FEATURES SUGGESTING VT
RELATED TO OLD MI
īPresence of Q waves (qR, QR or Qr) in related leads.
īNotched or wide QRS complexes.
īLow QRS voltage.
īMultiple ventricular tachycardia morphologies.
16. PRINCIPLES OF MANAGEMENT
īAcute Management:
īVTs with hemodynamic compromise: DC version.
īMedical management:
ī Amiodarone drug of choice.
ī Procainamide and sotalol are alternatives.
ī Lidocaine less effective in the absence of ischemia.
ī Beta blockers offer additional benefit.
īTreatment of underlying conditions (eg: acute ischemia, decompensated
heart failure, electrolyte abnormalities)
18. LONG TERM MANAGEMENT
īPrevention of SCD- ICD implantation.
īAdjunctive antiarrhythmic therapy
ī Reduce the frequency of ventricular arrhythmia in patients with unacceptably frequent
ICD therapy
ī Reduce the rate of VT so that it is better tolerated hemodynamically and more
amenable to pace termination or low-energy cardioversion
ī Suppress other arrhythmias (e.g., sinus tachycardia, AF, nonsustained VT) that cause
symptoms or interfere with ICD function resulting in inappropriate discharges.
īCatheter ablation of post-MI VT: 2 indications
ī Recurrent VT causing frequent ICD shocks and refractory to antiarrhythmic
medications
ī VT storm or incessant VT refractory to antiarrhythmic medications.
21. LONG TERM MANAGEMENT
PRIMARY PREVENTION OF SCD IN VENTRICULAR
ARRHYTHMIAS
TRIAL CONTROL NO OF
PTS
POPULATION MEAN FOLLOW
UP(mths)
MORTALITY
%
CONTROL
MORTALITY%
ICD
P
VALUE
MADIT Anti
arrhythmic
therapy
196 Prior MI; LVEF <
35%,
asymptomatic
NSVT
27 39 16 0.02
CABG-
PATCH
Anti
arrhythmic
therapy
900 For CABG: LVEF
< 35%. Positive
SAECG
32 21 22 0.64
MUSTT Conventional
therapy
704 Prior MI; LVEF <
40%; NSVT,
inducible VT on
EP study
39 48 24 0.001
MADIT II Conventional
therapy
1232 Prior MI; LVEF <
30%
20 20 14 0.007
DINAMIT Conventional
therapy
674 Recent MI
(within 6-40 d),
LVEF < 35%;
impaired heart
rate variability
39 18 17 0.66
22. GUIDELINES FOR ICD IN CAD
SECONDARY PREVENTION
īICD therapy is indicated in patients who are survivors of cardiac
arrest due to VF or hemodynamically unstable sustained VT
after evaluation to define the cause of the event and to exclude
any completely reversible causes. (Class I; LOE A)
īPatients experiencing cardiac arrest due to VF 48 hrs after MI
must be optimally evaluated and treated for ischemia.
īEvidence of ischemia â complete coronary revascularization.
īICD if revascularization is not possible and there is significant LV
dysfunction.
23. GUIDELINES FOR ICD IN CAD
PRIMARY PREVENTION
ī Class I:
īPatients with LVEF less than or equal to 35% due to prior MI who are at least 40
days post-MI and are in NYHA functional Class II or III. (LOE: A).
īPatients with LV dysfunction due to prior MI who are at least 40 days post-MI,
have an LVEF less than or equal to 30%, and are in NYHA functional Class I. (LOE:
A).
īPatients with nonsustained VT due to prior MI, LVEF less than or equal to 40%,
and inducible VF or sustained VT at electrophysiological study. (LOE: B).
24. VT IN DILATED CARDIOMYOPATHY
ī Multiform VPCs, ventricular pairs, NSVT- 80%-95% DCM patients.
ī Ventricular arrhythmias more frequent and complex as LV function
deteriorates.
ī NSVT 15%-20% in NYHA I/II to 50%-70% in NYHA IV.
ī VT may arise in the myocardium or may be through macroentrant
circuit ( BBR- VT).
ī BBR-VT --- Responsible for VT in up to 41% of DCM.
25.
26. PREDICTORS OF ARRHYTHMIAAND
MORTALITY
Clinical predictors
īļSeverity of LV dysfunction
īļ As CHF symptoms worsen,
īļ Risk of total mortality, sudden death and CHF death
increases.
īļ Ratio of sudden death to CHF death decreases.
īļ Once pt develop class IV symptoms, EF less
valuable in predicting mortality.
īļSyncope
īļ 1 yr SCD rates increases from 12% to 45% when
syncope is present.
27. ī Laboratory values:
ī Low serum sodium
ī High plasma norepinephrine, renin and ANP,BNP levels.
ī ECG predictors:
ī LBBB
ī First and second degree AV block
ī Predictive testing with EP in DCM patients not associated with CAD is
controversial.
ī Presence of polymorphic VT on EPS does not predict risk for SCD.
ī Induction of sustained monomorphic VT identifies high risk population.
ī Lack of inducible VT does not predict freedom from sudden death.
28. EFFECT OF HF THERAPY ON VENTRICULAR
ARRHYTHMIAS
ī Beta blockers: substantial part of the survival benefit seen
is due to a significant reduction in SCD.
29. EFFECT OF HF THERAPY ON VENTRICULAR
ARRHYTHMIAS
ī ACEI and ARBs: improved survival; conflicting data with reduction in SCD.
ī CONSENSUS, SOLVD, SAVE â little or no reduction in SCD.
ī V-HeFT, TRACE, AIRE â significant reduction in SCD.
ī Aldosterone antagonists: Reduce overall mortality and SCD in advanced HF.
ī Reduction in aldosterone effect on the heart
ī Maintenance of higher potassium levels
ī Digoxin and other inotropes: Proarrhythmic effect
ī DIG trial: no net mortality benefit, apparent increase in mortality from arrhythmias (
not statistically significant).
30. ANTIARRHYTHMICS:
ī Amiodarone:
ī Initial trials GESICA: mortality benefit.
ī SCD- HeFT: mortality not reduced compared to placebo.
ī Recommended only for reducing the frequency of shocks in patients with
recurrent ventricular arrhythmias (Class IIa).
32. ICD
ī Primary prevention of SCD:
ī Patients with nonischemic DCM who have an LVEF less than or equal to 35%
and who are in NYHA functional Class II or III. ( Class I; LOE B).
ī Patients with unexplained syncope, significant LV dysfunction, and
nonischemic DCM. ( Class IIa; LOE C).
ī Patients with nonischemic DCM who have an LVEF of less than or equal to
35% and who are in NYHA functional Class I. (Class IIb; LOE C).
ī Secondary prevention:
ī ICD is the preferred treatment in DCM patients with resuscitated cardiac
arrest from VT/VF.
33. BUNDLE BRANCH REENTRANT (BBR)
VT
īOnly reentrant VT with a well-defined reentry circuit.
īThe right bundle branch (RB) and left bundle branch (LB) obligatory limbs
of the circuit.
īConnected proximally by the His bundle (HB) and distally by the ventricular
septal myocardium.
īCannot be induced in patients with normal His Purkinje system (HPS)
ī Electrophysiological properties of normal HPS- very fast conduction velocity and a
relatively long refractory period precludes formation of a stable circuit.
34. EPIDEMIOLOGY
ī6% of induced sustained monomorphic VT.
īAdditional myocardial VTs in 25% patients.
īCommonly seen in patients with DCM.
ī DCM anatomic substrate in 45% of BBR-VT ; 41% of all VTs in DCM patients is BBR-VT.
īAlso seen in
o Ischemic cardiomyopathy (incidence 4.5 - 6%).
o Valvular heart disease
o Aortic or mitral valve surgery can facilitate BBR-VT- close proximity of HPS to valvular annuli.
o Ebsteinâs anomaly.
o Hypertrophic cardiomyopathy.
o Myotonic dystrophy.
o Conduction anomalies associated with sodium blockade with flecainide.
35. ī Changes from normal physiology for BBR to be sustained:
īļ Anatomically longer reentrant pathway (dilated heart)
īļ Slow conduction in HPS (HPS disease)
ī Sufficient prolongation of conduction time to allow expiration of refractory
period of HPS.
36. TYPES OF BBR-VT
ī LBBB morphology is commoner.
ī Type A and C are classical BBR-VTs.
ī Type B is most commonly seen in CAD especially those with AWMI with LAF or LPF block.
37. CLINICAL PRESENTATION
ī Typically unstable.
ī Very rapid ventricular rates (200-300/min) and poor underlying ventricular function.
ī 75% present with syncope or cardiac arrest.
ī Baseline ECG:
ī NSR or Atrial fibrillation.
ī Nonspecific IVCD and PR prolongation â most common ECG abnormality.
ī Typical bundle branch patterns may also be seen.
ī Rarely narrow baseline QRS complex- suggesting role of functional conduction delay.
ī ECG during VT:
ī Typical BBB pattern, may resemble that seen in NSR. LBBB>RBBB. Usually leftward axis.
ī Rapid intrinsicoid deflection in right precordial leads.
ī Initial ventricular activation through HPS, not ventricular muscle.
38. EP TESTING
īProlonged HV interval invariably present in sinus rhythm.
īSome patients with normal HV interval manifest as HV interval prolongation or
split HB potentials during atrial programmed stimulation or burst pacing.
īTachycardia Induction:
ī§ VES from RV apex usual method.
ī§ Dependent on achievement of critical conduction delay in HPS following VES.
ī§ At longer coupling intervals, retrograde conduction occurs through RB. At shorter
coupling intervals, retrograde block occurs in RB.
ī§ Retrograde conduction occurs via LB causing long V2-H2 interval.
ī§ Further shortening of coupling intervals, increased retrograde LB delay allowing
anterograde conduction of the RB ( beat with wide QRS LBBB pattern- BBR beat
or V3 phenomenon).
39. EP TESTING
īTachycardia features:
ī AV dissociation usually present; 1:1 ventriculoatrial conduction may occur.
ī His potential precedes the QRS.
ī HV interval during BBR similar or longer than that during baseline.
ī Spontaneous variations in V-V intervals are preceded and dictated by similar changes in H-H intervals.
ī Termination of VT with block in HPS.
ī Inability to induce VT after ablation of right or left bundle branch.
40. TREATMENT
ī Pharmacological therapy usually ineffective.
ī RFA of a bundle branch first line therapy.
ī RB ablation easier; method of choice.
ī LB ablation preferable in patients with conduction system disease such that
conduction down the LB is inadequate to maintain 1:1 conduction.
ī Mere presence of LBBB on ECG does not mean complete block in LB.
ī Pacemaker implantation indicated when infrahisian AV block is demonstrated
during atrial pacing or when postablation HV interval > 100 msecs.
ī Varies from 10-30%.
ī Prophylactic pacemaker in myotonic dystrophy patients in view of progressive nature of
the conduction system disease.
ī Recurrence rare. Mortality after successful ablation mostly due to progressive
heart failure and associated myocardial VTs (25%).
ī Treatment: ICD with or without CRT capabilities.
41. ARRHYTHMOGENIC RIGHT VENTRICULAR
DYSPLASIA(ARVD)
īProgressive disease in which normal
myocardium is replaced by fibrofatty tissue.
īUsually involves the RV; LV and septum may also
be involved.
īPredominantly involves the â Triangle of
Dysplasiaâ.
īOccurs in young adults (80% in less than 40
years) and more common in males.
īPrevalence 0.02 to 0.1%.
42. PATHOGENESIS
ī Several proposed theories.
ī Familial inheritance- autosomal dominant or recessive.
ī Metabolic disorder affecting RV.
ī Infectious or immunological cause.
ī Mutations in desmosomal proteins- desmoglein, desmoplakin, desmocollin, plakoglobin,
plakophilin.
ī Autosomal recessive inheritance
ī Familial palmoplantar keratosis, Naxos disease, mal de Meleda disease.
ī Hyperkeratosis of palms and soles, woolly hair.
ī Cardiac anomalies- 100 % penetrant by adolescence- RV involvement 100%, LV involvement
27%.
44. CLINICAL PRESENTATION
ī Fatigue, atypical chest pain, palpitations, syncope or sudden cardiac death.
ī Ventricular arrhythmias in ARVD- 23% (mild disease) to 100% (severe disease).
ī Occur during exercise.
ī Patients with ARVD with increased risk of SCD:
o Younger patients
o Patients with recurrent syncope
o Patients with previous history of cardiac arrest or VT with hemodynamic compromise
o Patients with LV involvement
o Patients with ARVD2 and Naxos disease
o Patients with an increase in QRS dispersion
47. ī Echocardiography:
ī Dilation of the RV and RV dysfunction (Revised task force criteria)
ī localised aneurysms in diastole
ī dyskinesis in the inferior basal region.
ī RV angiography:
ī Findings: infundibular aneurysms, trabeculae thicker than 4mm âdeep fissuresâ, prominent moderator
band, diastolic bulging of the subtricuspid area, mild tricuspid regurgitation.
ī Cardiac MRI:
ī Abundant epicardial adipose tissue, prominent trabeculations, scalloped appearance of RV free wall
and intramyocardial fat deposits.
ī Endomyocardial Biopsy:
ī Gold Standard; lacks sensitivity (67%). Performed from septum; changes more pronounced in free wall
48. MANAGEMENT
ī Pharmacological therapy:
ī Beta blockers, sotalol and amiodarone.
ī Class Ia and Ib drugs ineffective.
ī Radiofrequency ablation:
ī Frequently unsuccessful and may need multiple attempts.
ī Progressive nature of the disease and diffuse yet patchy nature (multiple arrhythmogenic foci)
ī Fontaine et al. reported success rates of 32%, 45% and 66% after one, two or three
ablation sessions in 50 patients.
ī ICD:
ī Patients with high risk of SCD.
ī Those resuscitated from cardiac arrest, history of syncope or life threatening arrhythmias not completely
suppressed by drug therapy.
ī Problems with ICD:
ī Areas of RV myocardium thin and non contractile â penetrated during RV lead placement leading to
tamponade.
ī Fibrofatty nature of RV â device inadequately sensing arrhythmias.
49. VT IN HCM
īHighly variable natural history.
ī Beta myosin heavy chain mutations: relationship between severity of LVH and risk of SCD.
ī Troponin mutations: high risk of SCD irrespective of LVH.
īMortality rates : 1%/yr.
ī SCD : 0.2%/yr.
īSCD
ī usually in patients with mild or no symptoms.
ī common in adolescents and young adults before the age of 30-35 yrs.
īPredominant mechanism of SCD: VT/VF
ī Other mechanisms: asystole, rapid atrial fibrillation, electrical mechanical dissociation.
50. SUDDEN CARDIAC DEATH
RISK FACTORS
Major risk factors
Prior personal history of sudden cardiac death or out-of-hospital cardiac arrest
Spontaneous sustained ventricular tachycardia or ventricular fibrillation
Family history of sudden cardiac death
Extreme left ventricular hypertrophy (>30 mm)
Nonsustained ventricular tachycardia
Abnormal blood pressure response to exercise
Recent, unexplained syncope
Delayed gadolinium enhancement on cardiac magnetic resonance imaging*
Presence of LVOT obstruction is not a sole risk factor for SCD.
EP study not shown to be of benefit for risk stratification in HCM.
51. PREVENTION OF SCD
ī ICD:
ī Patients with HCM who have 1 or more major risk factors for SCD. (Class
IIa; LOE: C)
ī Pharmacologic therapy: amiodarone
ī obsolete strategy; lacks proven efficacy.
ī Likelihood of side effects during the long risk period typical of young
patients with HCM.
52. VT LONG AFTER REPAIR OF
CONGENITAL HEART DISEASE
ī VT accounts for 38% of wide complex tachycardias in patients
with congenital heart disease.
ī VT late after repair occur in those with TOF and VSD.
ī Predictors for sustained VT:
ī QRS duration >180msec, rapid increase in QRS duration after repair,
dispersion of QRS duration on ECG, increased QT interval dispersion,
complete heart block, older age at surgery (>10yrs), presence of RVOT
patch, RVOT aneurysm, increased RV pressures, pulmonic or tricuspid
regurgitation.
ī Monomorphic and macrorentrant, rotating clockwise or
anticlockwise around myotomy scars or surgical patches.
53. VT IN PATIENTS WITH LV ASSIST
DEVICES
ī Not uncommon owing to significant underlying structural heart disease.
ī De novo monomorphic VT may occur after LVAD is implanted.
ī 60% suffer from monomorphic VT after implantation of LVAD.
ī Majority have an exit site close to the region of the inflow cannula at the LV
apex.
55. VT IN STRUCTURALLY NORMAL HEART:
ī Idiopathic Ventricular tachycardia
ī 10% patients with VT
ī Structural heart disease can be ruled out if - ECG, ECHO and
CAG are normal
ī However , MRI can detect RVOT origin VT despite all modalities
being normal
ī SPECT â single photon emission CT
56. IDIOPATHIC VT
ī Subclassified based on several criterias: mechanism, location,
response to therapy
ī OUTFLOW TRACT TACHYCARDIAS
ī IDIOPATHIC LEFT VTs (ILVT)
ī AUTOMATIC VTs
57. ī RVOT VT (80-90% of VT)
ī ILVT (idiopathic LV outflow tract)
ī IPVT (idiopathic propranolol sensitive VT)
ī CPVT (catecholaminergic polymorphic VT)
ī Brugada Syndrome
ī Long QT syndrome
VT IN STRUCTURALLY NORMAL HEART:
Inherited Ion-channelopathies
Taken from Supplement of JACC , 2007
58. OUTFLOW TRACT TACHYCARDIA
ī Account for most cases (80-90%)
ī Outflow tract encompases RV region between pulm & tricuspid
valves; AND basal left ventricle (including LVOT, aortic cusps)
ī Most commonly presenting as VPCs, Monomorphic nonsustained
VT
ī Sustained VT less common
ī Ppt: Exercise, emotional stress, exercise testing, menstrual cycles in
female
59. MECHANISM
ī DAD mediated triggered activity
ī Typically mediated by intracellular calcium overload through
increased intracellular cAMP
ī This explains Sensitivity to beta-blockers, CCBs
Lerman et al, Circulation 1995, 92
60. RVOT VT:
ī RV monomorphic extrasystoles are considered benign
ī This may progress to ARVD or RVOT VT, with MRI evidence of
functional/anatomical abnormality
ī ECG: LBB morphology, inferior Axis, QRS transition in V3/V4
ī Common in females of 30-50 yr age
ī Palpitation, presyncope, syncope (less common)
ī Exercise or emotional stress
ī Sudden death is rare
61. RVOT VT:
ī Two phenotypic forms:
ī Non-sustained repetitive monomorphic VT
ī Paroxysmal exercise induced sustained VT
ī Classification based on site of origin:
ī Originating from pulmonary artery
ī RV-end outflow tract
62. DIFFERENTIAL DIAGNOSIS OF RVOT VT
ī Atriofascicular fibers (Mahaim fibers)
ī AVRT using Rt-sided accessory pathway
ī VT after repair of TOF
ī ARVD
63. LVOT VT â
- CLINICALLY SAME LIKE RVOT VT
- MECHANISM ALSO SAME
ECG during VT shows
S wave in lead I
R-wave transition in
lead V1or V2(Earlier
precordial transition
zone)
More rightward axes
Taller R waves in
inferior leads
S wave in LI and R-wave transition in V1 suggest LVOT VT.
R:S amplitude ratio of 30% and R:QRS duration ratio of 50%
Presence of an S wave in leads V5 and V6 suggests an infravalvular
origin of the tachycardia.
64. ī May originate from supravalvular or infravalvular
endocardial region of coronary cusp of aortic
valve
ī
ī Distinction is important âRF ablation
ī
LVOT VT
65. OUYANG AND COLLEAGUES
RVOT VT Vs aortic cusp VT
R wave duration and R/S wave
amplitude ratio in leads V1 and
V2 were greater in tachycardias
originating from cusp compared
with RVOT
Precordial lead transition earlier
in cusp VT occurring before lead
V3
Absence of an S wave in V5 or
V6 -specificity of 88% for cusp
VT compared with RVOT VT
66. TREATMENT
âĸ Usually benign course
âĸ Good prognosis
1. May respond acutely to carotid sinus massage, Valsalva
maneuvers or intravenous adenosine or verapamil
2. Long-term oral therapy with either BB or CCB
3. Non-responders (33%)- class I or III antiarrhythmic agents
67. RFA
1. When medical therapy is ineffective or not tolerated
2. High success rate (>80%)
3. Ablation of epicardial or aortic sinuses sites is highly effective
4. Technically challenging and carries higher risks -proximity to
coronary arteries
5. Recurrence 10%
68. AUTOMATIC VENTRICULAR TACHYCARDIA
IPVT: PROPRANOLOL SENSITIVE
ī A form of IVLT
ī <50 yr, often ppt by exercise
ī Can arise from anywhere within heart
ī Unresponsive to Verapamil
ī Beta blockers very effective in terminating VT
ī Chances of SCD
ī ICD recommended in survivors
69. AHA/ESC GUIDELINES RECOMMENDATIONS
FOR TREATMENT:
ī Class IC: catheter ablation useful in drug refractory and symptomatic pts or
in pts who are intolerant to longterm drug therapy
ī Class IIa:
1. EP study reasonable for diagnosis in suspected outflow tract VT (LOA: B)
2. BB/CCB can be useful for symptomatic VT arising from RVOT (LOA: C)
3. ICD â can be effective therapy for sustained VT who are receiving chronic drug
therapy & who have reasonable expected survival for more than 1yr (LOA:C)
70. LONG QT SYNDROME
ī Seven types, based on different genes involved
ī LQT1, LQT2, and LQT3 account for 90%
ī LQT1 and LQT2 -mutations of KCNQ1 and KCNH2 genes that encode
subunits of IKs and Ikr potassium channels, respectively
ī LQT3 -mutations of SCN5A gene that encode subunits of INa sodium
channels
ī Approximately 25% not have identifiable gene mutations
71. LQT1 -often have broad-based T waves and frequently experience
events during physical activity (especially swimming).
LQT2- T-wave is often notched in multiple leads.
Triggers for LQT2 include startling auditory stimuli (e.g., from an alarm
clock) and emotional upset.
LQT3- often demonstrate long ST segments
Most LQT3 events occur at rest or sleep.
72.
73. MANAGEMENT
1. Avoid trigger events and medications prolong QT interval
2. Risk stratification schemes based on degree of QT prolongation,
genotype, and sex
3. Corrected QT interval exceeding 500 ms poses a high risk for
cardiac events
4. Patients who have LQT2 and LQT3 may be at higher risk for SCD
compared with patients who have LQT1
74. TREATMENT
1. BB are indicated for all patients with syncope and for asymptomatic
patients with significant QT prolongation (IB)
2. Role of BB in asymptomatic patients with normal or mildly prolonged
QT intervals remains uncertain.
3. BB are highly effective in LQT1, but less effective in other LQTS
4. Role of BBs in LQT3 is not established.
5. Because LQT3 is a minority of all LQTS,symptomatic patients who
have not undergone genotyping should receive BBs
75. âĸ ICD are indicated for secondary prevention of cardiac arrest and for
patients with recurrent syncope despite BB therapy
âĸ Less defined therapies
âĸ Gene-specific therapy with mexiletine , flecainide , or ranolazine for
some LQT3 patients
âĸ PPI for bradycardia
âĸ Surgical left cardiac sympathetic denervation for recurrent arrhythmias
resistant to BB therapy (class IIb, LOA-B)
âĸ Catheter ablation of triggering PVCs-abolish recurrent VT/VF
76. BRUGADA SYNDROME
âĸ Characterized by coving ST-segment elevation in V1 to V3
âĸ 2 mm in 2 of these 3 leads are diagnostic
âĸ Complete or incomplete RBBB pattern
âĸ Pattern can be spontaneously present or provoked by sodium-
channelâ blocking agents such as ajmaline,flecainide, or
procainamide
âĸ Typical ECG pattern can be transient and may only be detected
during long-term ECG monitoring.
77. CLINICAL PRESENTATION
âĸ Syncope or cardiac arrest
âĸ Predominantly in men in third and fourth decade
âĸ Also been linked to SCD in young men in Southeast Asia and has
several local names,including Lai Tai (âdied during sleepâ) in Thailand
âĸ Prone to atrial fibrillation and sinus node dysfunction
78. TREATMENT
âĸ No well-validated preventive medical therapy
âĸ Patients who donât have cardiac arrest risk stratified on the basis of
spontaneous ECG pattern and syncope
âĸ Lowdose quinidine may be used to treat frequent VAs in patients who
already have an ICD (Class IC)
âĸ Quinidine and isoproterenol may be useful in patients having VT storms
âĸ Catheter ablation of triggering PVCs and ablation of RV outflow
epicardial musculature successful in abolishing recurrent VT/VF in a
small number of patients
79. ROLE OF ICD
âĸ ICD are effective in preventing SCD and are indicated for cardiac
arrest survivors (Class IC)
âĸ Major management dilemma arises in decision to place
prophylactically an ICD based on patientâs perceived risk of SCD
80. 1. Patients with spontaneous ECG pattern and syncope are at high risk
and ICD insertion is generally recommended for primary prophylaxis
2. Asymptomatic patients with spontaneous ECG pattern are at
intermediate risk, and their best therapeutic options may need to be
individualized (class IIC)
3. Asymptomatic patients without spontaneous ECG pattern are at low
risk and may be followed up clinically
4. Family history of SCD and specific genotypes do not predict events
81. CATECHOLAMINERGIC PMVT.
Disorder of myocardial calcium
homeostasis
Clinically manifested as exertional
syncope and SCD due to exercise
induced VT
Often polymorphic or bidirectional
82. âĸ Autosomal dominant form involves mutation of cardiac ryanodine
receptor (RyR2 gene) in approximately 50% of patients
âĸ Autosomal recessive form, accounting for only 3% to 5% of
genotyped cases-mutations of calsequestrin 2 gene (CASQ2)
âĸ RyR2 and CASQ2 mutations cause intracellular calcium overload and
DAD -basis of arrhythmogenesis
83. âĸ Resting ECG is unremarkable
âĸ Typical VT patterns are reproducible with exercise or catecholamine
infusion
âĸ VAs typically appear during sinus tachycardia rates of 120 beats/min
to 130 beats/min, with progressive frequency of PVCs followed by
bursts of bidirectional VT
âĸ Mean age for presentation with syncope is 7.8 - 4 years
âĸ Electrophysiology study is not helpful in risk stratification
84. âĸ Mainstay of medical management is BB therapy
âĸ 46% may have recurrent events while receiving therapy
âĸ CCB may have limited effectiveness as adjunctive therapy
âĸ Flecainide blocks RyR2 receptor and shows promise as a medical
therapy
85. âĸ ICD insertion is appropriate for patients who had cardiac arrest and
with life-threatening VA despite maximal medical therapy
âĸ Recurrent ICD shocks may occur and an initial shock with its
accompanying pain and anxiety may trigger further VAs
âĸ Surgical left cardiac sympathetic denervation -resistant cases
CAST: Cardiac arrhythmia suppression trial.
EMIAT: European myocardial infarction amiodaraone trial.
CAMIAT: Canadian Amiodarone myocardial infarction arrhythmia trial
Absolute risk of SCD increases with worsening LV function but ratio of sudden to nonsudden deaths is inversely related to the extent of functional impairnment.
HF deaths
Sudden deaths
Other deaths.
CAT, Cardiomyopathy Trial; AMIOVIRT, Amiodarone vs. Implantable Defibrillator in Patients with Non-ischaemic Cardiomyopathy and Asymptomatic Nonsustained
Ventricular Tachycardia; DEFINITE, Prophylactic Defibrillator Implantation in Patients with Non-ischaemic-Dilated Cardiomyopathy; SCD-HeFT,
Sudden Cardiac Death in Heart Failure Trial;
In contrast to postoperative myocardial re entrant VT, BBR VT usually occurs in early postop period (<2 wks) and can be associated with preserved LV systolic function
Although total interruption of conduction in one of the bundle branches would theoretically prevent occurrence of bundle branch reentry, an ECG pattern of âcompleteâ bundle branch block may not be an accurate marker of complete block.
Ventricular extra stimuli
LB would still be capable of retrograde conduction because of the delay associated with transseptal conduction.
Favour LB ablation over RB:
Development of high grade AV block below the HB on transient RBBB that can occur secondary to RV catheter manipulation.
Observation of a LB potential following the ventricular electrogram either intermittently or during each sinus beat.
2 major or 1 major plus 2 minor or 4 minor criteria
RV angiogram : 45 RAO and 45 LAO
Endomyocardial biopsy gold standard: drawbacks lacks sensitivity only 67%. For safety reasons its performed only at the septum whereas typical changes are more pronounced in the free wall.
Beta blockers reduce the possibility of adrenergically stimulated arrhythmia.