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Syncope Risk Stratification Systems:Current Limitations, Future Prospects

David G Benditt MD FACCUniversity of Minnesota Medical School

Arrhythmia and Syncope CenterMinneapolis, Minnesota

Relevant Conflicts of Interest

None

Syncope & Collapse:Not all Collapse is Syncope

Careful History and Evaluation is Needed

The Problem

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• Syncope and Collapse are Costly• 〰740,000 ED Visits in US /year• 〰 250,000 Hospital Admissions

• $US 2.4 Billion in Hospital Costs • 〰 Approx 30% hospital admission rate• Triggered by concern for adverse outcomes

• Hospital evaluations • Expensive• Low diagnostic and treatment yields

Risk Stratification Determines Need For:

• Immediate hospitalization vs outpatient assessment based on:• Likelihood of cardiac syncope• Injury or potential injury risk• Ability to care for self

• Early intensive evaluation• Outpatient monitoring vs invasive study (e.g., EPS)

• Nature of subsequent management • Referral to other specialty (e.g., neurology, psychiatry)

Effective Risk Stratification Schemes Should:• Diminish Number of Hospitalizations• Enhance Evaluation Efficiency and • Reduce Costs

Current Risk Stratification Schemes:Short-term

Current Risk Stratification Schemes: Longer-term

Predictors of Mortality in EGSYS2Ungar et al, Eur Heart J 2010

Derivation Cohort Validation Cohort

Mo

rtal

ity

Risk Stratification

• Currently best for addressing near-term risks (1 wk to 1 mo) • Death, injury, • Syncope recurrence, • Early Return to ED or Hospitalization

• Less successful for longer-term adverse events• Often unclear if syncope increases risk of underlying

disease• Impact on QoL & independent lifestyle unclear

Multiple Risk Stratification Schemes

• Many Proposals: None are Optimal • Differing Risk Identifiers in Various Reports: Only ECG is Common• End-points Vary: Mortality, Injury, Re-Hospitalization• Small Sample Sizes, Often Single Center• Largely Caucasian population, Not Multicultural• Validation Studies Not Standard

Risk Stratification: Limitations

ACC/AHA/HRS 2016

Standardized Definitions and Data ReportingCurrently even definition of ‘syncope’ varies

ESC 2009

Necessary Adaptations of Current Risk Stratification Schemes:

Classify Risk by Patient Subsets

• Standard definitions• ‘Healthy’ fainters vs structural disease• Collapse in the elderly vs younger patients• Short-term (ED) vs Long-term Outcomes• Accommodate expanding literature• Syncope may not increase mortality risk

in some diseases• But may increase injury and cost of care

risk

Corrado et al Circ 2003

Syncope as Risk Factor in ARVC Comparable to other risks

Risk factors-massive

hypertrophy

-SCD hx

-NSVT

-SUO

HCM: Risk Factors for Appropriate ICD Shock

Syncope in Hypertrophic CMSpirito et al Circulation 2009

Syncope During Beta-Blocker in LQTS:

17Jons et al JACC 2010

Syncope Risk Stratification Goals for the Future

• Multicenter / Multicultural trials• Larger numbers of patients• Sub-group assessment (e.g., SHD vs no-SHD)

• Risk marker identification• Development group• Validation test group

• SMU availability may diminish hospitalization need• ‘Big’ Data

• Leverage centrally collected data from implanted and/or wearable diagnostic devices to develop better understanding of risk factors

Factors That Enhance Risk Marker Identification

• Practice guideline recommendations• Greater awareness of need

• Specialized practices• Syncope management units (SMUs)

• Enhanced patient monitoring to define diagnoses• Remote monitoring• Development of ECG/Hemodynamic monitors

Advanced Outpatient Diagnostics:May Improve Accuracy and Reduce Cost

Incorrect Diagnoses are Costly and Potentially Hazardous

Future of Risk Stratification:

• Standardized definitions• Syncope vs TLOC

• Time frames (days/weeks vs years)

• Standard risk category reporting• Death

• Injury

• etc

• Clarify patient risk subsets instudies• ‘Healthy’ vs SHD

• Disease dependent risk

• Multicenter studies• Large samples

• Uniform follow-up

• Validation studies

Current Risk Stratification Limitations

• Which ‘risk’ is the end-point of interest:• Mortality• Injury• Repeat hospitalization• Loss of independence, occupation

Syncope Management Units (SMUs)

• Facilitate uniform data collection• Increasingly widespread• Models vary with health care system design /

Practitioner preference• ED based (SEEDS)• Outpatient clinic• In-hospital Units• Mixed

Structured Care with SMUs:Current Approach is Inefficient

• Currently approx 35% of Syncope/Collapse are hospitalized• Probably about ½ that number is appropriate

• Hospital diagnostic evaluation is generally ineffective and inefficient

• Syncope Management Units (SMUs) may improve diagnostic capability at lesser cost

Implantable Cardiac Monitors (Insertable and Wearable Loop Recorders

ILRs/WLRs• Invaluable for arrhythmia diagnosis

• Limitations• : Unable to determine hemodynamic impact of detected

arrhythmias, or

• confirm hypotension in symptomatic patients

• Addition of hemodynamic monitors• Could offer more comprehensive assessment of

arrhythmias in free-living subjects

ILR-detected Unexplained Syncope:About 1/3 are in sinus rhythm –other diagnostic tools are needed

Asyst Brady Normal SR Tachy Total

Pilot study

Circulation, 95

? 7(47%) 6(40%) 2(13%) 15/16 94%

Krahn et al

Circulation, 99

? 14(69%) 7(30%) 2 (9%) 23/85 27%

Nierop et al

PACE, 2000

? 4(29%) 6(43%) 4(29%) 14/35 40%

ISSUE study 16(50%) 3(9%) 12(34%) 1 (3%) 32/111

29%

Total 44

52%

31

37%

9

11%

84/247 34%

Future ILR/WLR Monitoring

• Remote interrogation• Wireless mobile interrogation, 24/7 monitoring• Voice-activated for symptom reporting• GPS to facilitate summoning assistance

• Novel sensors• Assess hemodynamic impact of rhythm disturbances • Evaluate clinical posture / activitywhen events occur

• New Applications• ‘Seizure’ evaluation• Heart failure monitoring

Advanced Diagnostics for Ambulatory Patients:

Distinguishing Faints from Falls

•ECG•BP/Flow•EEG•Position•Blood sugar

Combo Device

The Future

“The future, according to some scientists, will be exactly like the past

…only far more expensive”John Sladek (1937-2000)

Science Fiction AuthorDied Minneapolis, MN

Summary• Guidelines from ESC and ACC/AHA/HRS provide direction

• Need multidisciplinary acceptance

• Risk Stratification and SMU concepts seem appropriste steps• Current evidence is positive but studies are small

• Supportive multicenter studies needed

• Thoughtful study design / end-points

• Advanced monitoring technology may• Speed diagnosis

• Differentiate falls from faints (possibly from seizures)

Identifying Patients with

Cardiac Causes of Syncope is a

Primary Risk Stratification

Goal:• Increasing Age

• Co-morbidities

• CV Drugs

Syncope as Risk Factor in HCMSpirito 2009

Miniaturized ICM Device

87% smaller and

wireless transmissions

3-year monitoring

remote management

38

Medtronic Confidential. Internal Use Only.

How Do Specific Diseases Impact

Mortality/SCD Risk?

• Varies by diagnosis

• Many uncertainties remain- Most reports examine mortality not SCD

- Evolving knowledge base

Steinberg et al JCE 2001

Mortality & Arrhythmia in AVID

Syncope Substudy

Syncope in SCD Heft:Associated with Increased Mortality

Trends…but not SCDOlshansky et al JACC 2008

Not Prevented by ICD

Eur Heart J Supp 1989

More recent multicenter ARVC study in press plays down Syncope as risk factor

unless associated with VT or NSVTMarcus et al JACC EP (in press)

SMU Potential Economic BenefitsEGSYS 2 , Eur Heart J 2006