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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