2017 AHA/ACC/HRS Ventricular Arrhythmias & Sudden Cardiac Death Guidelines — Quick Reference

What's New in 2017

This guideline update reflects the most current evidence on ventricular arrhythmias and sudden cardiac death management, with emphasis on:

Refined ICD indications for primary prevention in ischemic (LVEF ≤35%, ≥40 days post-MI, ≥3 months GDMT) and non-ischemic cardiomyopathy (LVEF ≤35%, ≥3 months GDMT)
Inherited arrhythmia syndrome risk stratification: LQTS (Schwartz score), Brugada (automated risk calculator), CPVT (catecholamine challenge), HCM (HCM Risk-SCD), ARVC (Task Force diagnostic score)
Genetic testing and counseling for familial SCD risk (Class I, Level C-EO)
Wearable cardioverter-defibrillator (WCD) therapy for bridge-to-ICD scenarios and acute heart failure
Catheter ablation for recurrent VT/VF refractory to antiarrhythmic drugs, particularly in structural heart disease
Perioperative risk management in patients with VA/SCD risk undergoing elective procedures
Shared decision-making and patient-centered care in ICD programming, exercise restriction, and end-of-life discussions

VT/VF Classification & Definitions

Ventricular Tachycardia (VT)

Definition: Three or more consecutive ventricular complexes at a rate >100 bpm with cycle length <600 ms.

VT Morphology Subtypes:

Monomorphic VT: Stable single QRS morphology from beat to beat; indicates fixed anatomic substrate (scar reentry)
Polymorphic VT: Changing/multiform QRS complexes; suggests abnormal automaticity or triggered activity
Bidirectional VT: Beat-to-beat alternation in QRS axis/morphology in frontal plane; classic in CPVT and digitalis toxicity
Torsades de pointes: Polymorphic VT with twisting axis pattern; occurs in setting of QT prolongation (LQTS, drug-induced, hypokalemia)

Clinical VT Categories:

Sustained VT: Continuous for ≥30 seconds or requiring termination due to hemodynamic compromise
Nonsustained VT (NSVT): Runs <30 seconds that self-terminate; common in HCM, ischemic cardiomyopathy
Incessant VT: Continuous or nearly continuous VT; medical emergency requiring aggressive treatment

Ventricular Fibrillation (VF)

Definition: Rapid (>300 bpm), grossly irregular electrical activity with no organized QRS complexes. Hemodynamically unstable; results in cardiac arrest without effective perfusion. Requires immediate defibrillation.

Acute VT/VF Management (ACLS & IV Antiarrhythmics)

Pulseless VT/VF Algorithm

Immediate Actions

1. Check responsiveness & pulse: If unresponsive + pulseless → Cardiac arrest

2. Activate EMS / Call code

3. Start CPR: Chest compressions at 100–120/min with adequate depth (2–2.4 inches). Maintain low interruption time.

4. Defibrillation: Apply AED/defibrillator pads. If VF on monitor → Defibrillate immediately (biphasic 120–200 J or monophasic 360 J). Resume CPR immediately after shock.

IV Antiarrhythmic Medications for Cardiac Arrest

IV Amiodarone (Class IIa)

Dosing (Cardiac Arrest): 300 mg IV push for first dose. If refractory to defibrillation, may give 150 mg over 10 minutes after 5 min interval.

Maintenance (Post-ROSC): 0.5–1 mg/min IV infusion.

Key Monitoring: QT interval, liver function, thyroid function (TFTs), bradycardia, hypotension.

Advantages: Broad-spectrum antiarrhythmic; alpha/beta/calcium/potassium channel blockade; also slows AV node.

Disadvantages: Increased mortality in post-MI with reduced LVEF (CAST trial); long half-life; toxicity with chronic use.

IV Lidocaine (Class IIb)

Dosing: 1–1.5 mg/kg IV push (typically 75–100 mg), followed by 0.5–0.75 mg/kg q5–10min. Max 3 mg/kg in 1 hour.

Maintenance: 1–4 mg/min IV infusion.

Onset: <5 minutes (IV).

Key Monitoring: CNS toxicity (tremor, confusion, seizures at high levels); hypotension.

Use: Preferred in acute MI with VT/VF; safer in hemodynamic instability than amiodarone.

IV Procainamide (Class IIb)

Dosing: 10–15 mg/kg IV at 20–50 mg/min (slower infusion if hypotension). Max 1 g total.

Maintenance: 1–4 mg/min infusion.

Key Monitoring: QRS widening (stop if >50% baseline), QT prolongation, ANA (lupus-like syndrome), hypotension.

Use: Alternative if amiodarone/lidocaine contraindicated; less commonly used in cardiac arrest.

Post-Resuscitation Care (After ROSC)

Therapeutic hypothermia / targeted temperature management (TTM): 32–36°C for 12–24 h if comatose post-SCA
Coronary angiography: Urgent if SCA secondary to ACS
Continuous cardiac monitoring: In ICU; manage electrolytes (K+, Mg2+)
Deferred ICD placement: Often deferred until 24–48 h post-resuscitation

ICD Indications (Primary & Secondary Prevention)

Secondary Prevention ICD

Recommended for:

Survivors of cardiac arrest due to VF or sustained VT
Sustained monomorphic VT with hemodynamic compromise (syncope or hypotension)
Sustained polymorphic VT or VF post-MI
Electrical storm (≥3 VT/VF episodes in 24 h) despite antiarrhythmics

Primary Prevention ICD — Ischemic Cardiomyopathy

Class I Indications:

All of the following:

LVEF ≤35% on guideline-directed medical therapy (GDMT)
≥40 days post-myocardial infarction
≥3 months of stable GDMT
NYHA functional class II or III

Primary Prevention ICD — Non-Ischemic Cardiomyopathy

Class I Indications:

All of the following:

LVEF ≤35% on GDMT
≥3 months GDMT optimization
NYHA functional class II or III

Specialty ICD Indications

HCM

HCM Risk-SCD ≥4%: 5-year SCD risk calculator

LQTS

Genotype-dependent: High-risk mutations; breakthrough events

Brugada

Risk factors: Prior SCA, spontaneous Type 1 ECG

CPVT

Breakthrough arrhythmias: Despite beta-blockers

Antiarrhythmic Drug Table: Dosing, Monitoring & Contraindications

Drug (Class)	IV Dosing	Oral Dosing	Key Monitoring	Contraindications
Amiodarone (I/II/III/IV)	300 mg push, then 150 mg/10min	600–800 mg/d × 1 wk, then 200–400 mg/d	QT, LFTs, TSH, PFTs, HR/BP	Bradycardia <45, AV block, SaO₂ <90%
Sotalol (III + beta-blocker)	Not available IV	80–160 mg BID (reduce if CrCl <60)	QTc, K+, Cr, HR; torsade risk	QTc >500 ms, CrCl <20, bradycardia
Mexiletine (IB)	Not available IV	200–300 mg TID (max 1200 mg/d)	CNS, GI, CBC	Cardiogenic shock, AV block
Dofetilide (III)	Not available IV	125–500 mcg BID (renal dosing)	QTc (baseline, d1, d2, d5), K+, Cr	QTc >500 ms, CrCl <20
Procainamide (IA)	10–15 mg/kg @ 20–50 mg/min	250–500 mg q3–6h	QRS, QT, ANA, CBC, BP	Cardiogenic shock, SLE

Special Considerations

Avoid amiodarone chronically in post-MI + reduced LVEF: CAST trial showed increased mortality with Class I drugs.

Drug interactions: Amiodarone increases digoxin, warfarin, statin levels. Sotalol/dofetilide require strict QTc monitoring and electrolyte management.

VT Ablation Indications & Approach

Class I Indications (Recommended)

VT Ablation Strongly Indicated:

Incessant VT: Continuous or recurrent VT despite IV antiarrhythmics
Scar-related VT: Monomorphic VT in post-MI cardiomyopathy with failed medical therapy
Idiopathic VT (curative): RVOT, fascicular VT in structurally normal hearts
VT storm: ≥3 VT/VF episodes in 24 h; substrate-based ablation

Pre-Ablation Workup

12-lead ECG (assess VT axis, QRS width, morphology)
Cardiac MRI (identify scar/fibrosis location)
Electrophysiology study: Diagnostic & therapeutic
Angiography if structural disease suspected

Ablation Success & Recurrence

Idiopathic VT: 80–95% acute success, <10% recurrence at 1 year
Structural heart disease (post-MI): 60–80% success; higher recurrence (20–40%)
ARVC: 70–85% success; multiple procedures often needed

Inherited Arrhythmia Syndromes: Risk Stratification & Management

Long QT Syndrome (LQTS)

Genotype-Specific Therapy:

LQT1: Beta-blockers (first-line); avoid swimming; ICD for breakthrough on beta-blockers
LQT2: Beta-blockers; ICD if syncope on therapy; auditory triggers problematic
LQT3: Na+ channel blockers (mexiletine, flecainide); ICD for recurrent syncope

Risk Stratification (Schwartz Score):

Integrated assessment of QTc, family history, syncope, gender, genotype. Score ≥4: High risk.

Brugada Syndrome

Diagnosis:

Type 1 ECG (diagnostic): Coved ST elevation ≥2 mm in V1–V2. Provocation testing in suspected cases.

Risk Factors for SCD:

Spontaneous Type 1 ECG (vs. fever-induced)
Prior syncope or SCA
Male gender (8–10× higher incidence)
Fever sensitivity
Inducible VF on electrophysiology study

Management:

ICD for: Prior SCA, spontaneous Type 1 + multiple risk factors
Fever management: Strict fever control; avoid hot environments
Drug avoidance: No flecainide, ajmaline, TCAs

CPVT (Catecholaminergic Polymorphic VT)

Genetics:

RYR2 mutations (70%): Autosomal dominant; abnormal calcium handling.

Clinical Features:

Syncope/SCA during exercise, swimming, or extreme emotion
Normal QT interval at rest
Exercise test provokes bidirectional/polymorphic VT

Management (Class I):

Beta-blockers (first-line): High-dose (propranolol, nadolol)
Flecainide (Class IB): 100–200 mg/d; reduces Ca2+ leak
ICD (secondary prevention): Breakthrough arrhythmias despite maximal medical therapy
Lifestyle modification: Exercise restriction; stress management

Short QT Syndrome

Diagnosis:

QTc <350 ms on ECG. Rare genetic channelopathy.

Management:

ICD: Recommended for high-risk patients
Quinidine (Class IA): Broadens QT interval (limited data)

PVC Management: From Benign to PVC-Induced Cardiomyopathy

PVC-Induced Cardiomyopathy

Definition & Threshold:

PVC burden >10–15% of total beats per 24 hours can lead to reversible LV dysfunction in structurally normal hearts.

Diagnosis:

Holter/telemetry: High PVC burden (>1000–2000 PVCs/24h)
Echocardiogram: Reduced LVEF, LV dilatation
Stress test: PVC suppression with exercise

Management:

Beta-blockers: First-line; reduce PVC burden
Antiarrhythmics: Sotalol or flecainide if beta-blockers ineffective
Catheter ablation: Definitive treatment; >80% successful

Frequent PVCs in Structurally Normal Heart

Generally Benign — Management Approach:

Reassurance: No increased mortality if structurally normal
Avoid triggers: Caffeine, stimulants, sleep deprivation
Treatment if symptomatic: Beta-blockers or calcium channel blockers
Screening: Annual ECG + Holter if high burden

VA/SCD Risk in Specific Cardiomyopathies

Ischemic Cardiomyopathy (Post-MI)

Arrhythmia Mechanism:

Scar reentry: Heterogeneous scar tissue creates substrate for monomorphic VT.

ICD Indications:

Primary prevention: LVEF ≤35% on GDMT ≥40 days post-MI, ≥3 months GDMT.

Non-Ischemic Dilated Cardiomyopathy (DCM)

ICD Indications:

Primary prevention: LVEF ≤35% on GDMT ≥3 months, NYHA II–III.

Special Considerations:

Myocarditis: Wait 6 months for LVEF recovery before ICD
Peripartum cardiomyopathy: Defer ICD unless persistent LVEF ≤35% at 6 months postpartum

Hypertrophic Cardiomyopathy (HCM)

SCD Risk Assessment (HCM Risk-SCD Calculator):

≥4% 5-year SCD risk: ICD consideration.

Non-ICD Management:

Beta-blockers or calcium channel blockers
Disopyramide: If gradient persists
Exercise restriction: Avoid competitive sports if high-risk

ARVC (Arrhythmogenic Right Ventricular Cardiomyopathy)

ICD Indications:

Prior SCA/sustained VT (secondary prevention)
Extensive RV replacement + family history SCD

Management:

Beta-blockers: First-line antiarrhythmic
Catheter ablation: Effective; substrate-targeted approach
Exercise restriction: Endurance sports contraindicated

Cardiac Sarcoidosis

ICD Indications:

Reduced LVEF ≤35%
Extensive infiltration on cardiac MRI
Sustained VT/prior SCA

Medical Therapy:

Corticosteroids: If active granulomatous inflammation
Standard HF drugs: ACE-I, beta-blockers, aldosterone antagonists

Wearable Cardioverter-Defibrillator (WCD) Indications

When to Consider WCD (Class IIa)

Clinical Scenarios:

Bridge to ICD: First 40 days post-MI with LVEF ≤35%
Acute heart failure: Recent onset LVEF ≤35% (<3 months)
Myocarditis acute phase: Temporary protection during recovery
Incessant VT/electrical storm: Temporary protection while optimizing therapy
Post-heart transplant graft vasculopathy: Pending revascularization decision
Perioperative risk: High-risk patient undergoing major surgery

WCD Advantages & Limitations

Advantage	Limitation
Non-invasive; no surgical risk	Requires consistent daily wear
>99% defibrillation success	Skin irritation, discomfort
Reversible; allows LVEF recovery monitoring	False alarms possible
Rapid deployment; cost-effective bridge	Patient education required

Exercise & Sports in Patients With VA/SCD Risk

High-Risk Settings by Diagnosis

LQTS: Swimming, auditory triggers (LQT2), rest pauses (LQT3)
Brugada: Fever, extreme exertion in heat, sauna
CPVT: High-intensity exercise, extreme emotional stress
HCM: Competitive sports with sudden exertion
ARVC: Endurance sports, high-intensity exercise

General Exercise Recommendations

DO:

Baseline risk assessment: 12-lead ECG, Holter, exercise stress test
Restrict competitive sports if high SCD risk
Allow mild–moderate recreational exercise with cardiology clearance
Genetic counseling: Screen family members

DON'T:

Unrestricted competitive sports without ICD in high-risk syndromes
Ignore syncope history
Assume benign PVCs in athletes without testing

Special Populations: Pregnancy, Elderly, CKD

Pregnancy

ICD Management:

Device delivery/interrogation: Possible but requires expertise
Medication changes: Amiodarone, sotalol, procainamide relatively safe
Hemodynamic changes: Increased cardiac output may unmask arrhythmias

Counseling Points:

Discuss ICD benefit vs. fetal risk before conception
Coordinate care (cardiology, obstetrics, anesthesia)
Avoid ACE-I in first trimester

Older Adults (≥75 years)

ICD Benefit:

Age alone NOT a contraindication: If LVEF ≤35% post-MI (≥40 days, ≥3 mo GDMT), ICD improves survival regardless of age.

Special Considerations:

Comorbidities: Renal dysfunction affects drug dosing
Drug interactions: Polypharmacy; amiodarone interactions
QT-prolonging drugs: Higher torsade risk
End-of-life planning: ICD deactivation if prognosis limited

Chronic Kidney Disease (CKD)

Antiarrhythmic Dosing Adjustments:

Sotalol: CrCl 30–60 → 50% dose reduction; CrCl <30 → avoid
Dofetilide: Strict renal dosing; CrCl <20 → contraindicated
Procainamide: CrCl <50 → reduce dose
Mexiletine: CrCl <20 → reduce dose

Electrolyte Management:

Hyperkalemia: High-risk in CKD; monitor QT-prolonging drugs
Hypomagnesemia: Increase torsade risk; supplement if <2 mg/dL

Clinical Pearls: Do's & Don'ts

DO:

Hospitalize all patients with syncope + documented/suspected VA
Obtain 12-lead ECG + Holter monitor in all wide complex tachycardias
Perform genetic testing + genetic counseling in young patients with unexplained SCA
Optimize GDMT for ≥3 months in non-ischemic HF; ≥40 days in post-MI before ICD
Risk stratify HCM, ARVC, LQTS, Brugada, CPVT with genotype-specific tools
Monitor QT, K+, Cr, liver function on Class III antiarrhythmics
Avoid triggers: Fever in Brugada, swimming in LQTS, high-intensity exercise in CPVT
Use cardiac MRI to evaluate structural disease and identify VT substrate
Consider catheter ablation for incessant VT, electrical storm, or refractory VT

DON'T:

Avoid ICDs solely based on age; benefit extends across age spectrum
Use amiodarone chronically as monotherapy in acute post-MI + reduced LVEF
Miss genetic diagnoses in young unexplained SCA or syncope
Ignore family history; screen for inherited arrhythmia syndromes
Delay post-resuscitation coronary angiography in unexplained SCA
Rely on antiarrhythmic monotherapy alone for incessant VT/electrical storm
Assume benign PVCs in young/athletic patients without testing
Forget QT-prolonging drug interactions
Omit genetic counseling in inherited syndromes

Interactive Calculators & Risk Tools

Below are clinical decision-support calculators embedded from the guideline-aligned repository: