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Sudden Cardiac Death and its Relation to Previously Diagnosed or Occult Cardiac Disease at Autopsy
James W Salazar1, Kosuke Nakasuka1, Andrew J Connolly2
1Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California-San Francisco, San Francisco, California, USA.
Insights
Two-thirds of sudden cardiac deaths (SCDs) occur in individuals without diagnosed risk factors, with half showing occult myocardial infarction (MI) or dilated cardiomyopathy (DCM). Improved detection of silent cardiac disease is crucial for prevention.
Area of Science:
- Cardiology
- Forensic Pathology
- Public Health
Background:
- Sudden cardiac death (SCD) prevention typically targets individuals with known risk factors like reduced ejection fraction and myocardial infarction (MI).
- The prevalence of undiagnosed cardiac disease in community SCDs lacking conventional risk factors is largely unknown.
- Identifying occult cardiac pathology in these cases is essential for developing new prevention strategies.
Purpose of the Study:
- To determine the sensitivity of diagnosed risk factors in predicting community sudden deaths.
- To identify the cardiac pathology, including occult MI and dilated cardiomyopathy (DCM), present in community sudden deaths without previously diagnosed risk factors.
Main Methods:
- The study utilized autopsy data from the POstmortem Systematic invesTigation of Sudden Cardiac Death (POST SCD) registry.
- Autopsies adjudicated deaths as arrhythmic or nonarrhythmic, assessing diagnosed risk factors (e.g., ejection fraction ≤35%, prior MI).
- Occult cardiac pathologies like DCM and healed MI were evaluated in arrhythmic deaths without diagnosed risk factors.
Main Results:
- Of 877 presumed SCDs, 513 were arrhythmic deaths; only 32% had diagnosed risk factors.
- An additional 31% of arrhythmic deaths had occult MI or DCM, with similar demographics and cardiac pathology to those with diagnosed risk factors.
- The remaining 36% of arrhythmic deaths, though younger, showed increased heart weight, larger ventricular diameter, and more coronary disease compared to trauma deaths.
Conclusions:
- A significant majority of community arrhythmic SCDs occur in individuals without diagnosed disease, highlighting a gap in current risk assessment.
- Half of these "silent" SCDs exhibit occult MI or DCM, emphasizing the need for improved diagnostic approaches.
- Enhanced detection of underlying cardiac pathologies is a critical priority for reducing the burden of community sudden cardiac deaths.
Background:
Sudden cardiac death (SCD) prevention focuses on individuals with diagnosed disease (ie, conventional SCD risk factors [RFs]) such as reduced ejection fraction and myocardial infarction (MI). The burden of occult disease among community SCDs without diagnosed RFs is unknown and represents a target for prevention through increased detection.
Objectives:
This study sought to determine the sensitivity of diagnosed RFs for community sudden deaths and identify cardiac pathology, including occult MI and dilated cardiomyopathy (DCM), among community sudden deaths without diagnosed RFs.
Methods:
The POST SCD (POstmortem Systematic invesTigation of Sudden Cardiac Death) is a prospective countywide study using autopsy to adjudicate arrhythmic (potentially rescuable with defibrillator) or nonarrhythmic (eg, tamponade, overdose) deaths among presumed SCDs meeting World Health Organization criteria. We assessed prevalence ("sensitivity") of diagnosed RFs (ejection fraction ≤35%, heart failure, prior MI, syncope) among arrhythmic, nonarrhythmic, and reference trauma deaths. Among arrhythmic deaths without diagnosed RFs, we assessed occult cardiac pathologies including DCM (short-axis diameter ≥3.5 cm and heart weight 1 SD more than expected based on sex, age, height, and weight; Z-score =1) and healed MI (histopathological evidence of healed MI).
Results:
Of 877 presumed SCDs, 513 (58%) were autopsy-defined arrhythmic deaths, of which 166 subjects (32%) had diagnosed RFs (mean age: 64.3 years; 77% men); therefore, sensitivity of RFs for arrhythmic death was 32%. Another 159 subjects (31%) had occult MI or DCM with similar demographics (mean age: 62.6 years; 80% men) and cardiac pathologies as those with RFs, including fibrosis and coronary disease. The remaining 185 arrhythmic deaths (36%) were subjects who were younger (mean age: 56.9 years) with less cardiac pathology than arrhythmic deaths with occult MI or DCM but still had increased heart weight (Z-score: 0.9 vs 0.0), larger left ventricular diameter (2.5 cm vs 1.9 cm), and more significant coronary disease (52% vs 13%, all P < 0.001) but similar fibrosis (6.7% vs 6.3%) and left ventricular hypertrophy burden (57% vs 55%) than trauma deaths.
Conclusions:
In this 12-year countywide postmortem study, two-thirds of community arrhythmic SCDs occurred in individuals without diagnosed disease despite substantial cardiac pathology; half of these "silent" arrhythmic deaths had occult MI or DCM. Improved detection of occult cardiac disease is a critical priority to reduce community sudden deaths.
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