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Risk factors for sudden cardiac death in middle-aged British men
G Wannamethee1, A G Shaper, P W Macfarlane
1University Department of Public Health, Royal Free Hospital School of Medicine, Glasgow, Scotland.
Insights
Sudden cardiac death (SCD) risk factors like heavy drinking, elevated heart rate, and arrhythmia appear specific. These, along with age and cholesterol, increase SCD risk, with other factors varying based on prior heart disease history.
Area of Science:
- Cardiology
- Preventive Medicine
- Epidemiology
Background:
- Sudden cardiac death (SCD) risk factors remain poorly understood.
- Heavy drinking and elevated heart rate are potential contributors to SCD.
- This study investigates established and potential risk factors for ischemic heart disease (IHD) and SCD.
Purpose of the Study:
- Identify independent risk factors for SCD.
- Determine factors specifically related to SCD.
- Examine how risk factors differ in individuals with and without pre-existing IHD.
Main Methods:
- Prospective cohort study of 7735 middle-aged men followed for 8 years.
- Analysis of 488 major IHD events, including 117 (24%) SCDs.
- Statistical adjustment for a wide range of potential confounding factors.
Main Results:
- Independent risk factors for SCD included age, pre-existing IHD, arrhythmia, systolic blood pressure, blood cholesterol, elevated heart rate, and physical activity.
- Smoking, HDL cholesterol, and elevated hematocrit showed a lesser association with SCD.
- Elevated heart rate, heavy drinking, and arrhythmia appeared specific to SCD, distinct from other IHD events.
Conclusions:
- Three risk factors (elevated heart rate, heavy drinking, arrhythmia) seem specific to SCD.
- Risk factor impact varies significantly between individuals with and without pre-existing IHD.
- Findings offer insights into the causes and prevention strategies for SCD.
Background:
Risk factors specific to sudden cardiac death (SCD), ie, death within 1 hour after onset of symptoms, have been poorly identified, although recent findings from the present study incriminate heavy drinking and elevated heart rate. This paper examines the relations between a wide range of established and potential risk factors for ischemic heart disease (IHD) and SCD to identify independent risk factors for SCD and factors that might particularly or specifically relate to SCD.
Methods And Results:
We present a prospective study of a cohort that was drawn from general practices in 24 British towns of 7735 middle-aged men who were followed up for 8 years. During 8 years of follow-up, the men experienced 488 major IHD events (nonfatal and fatal), of which 117 (24%) were classified as SCD. Age, preexisting IHD, arrhythmia, systolic blood pressure, blood cholesterol, elevated heart rate (> or = 90 beats per minute), physical activity (all, P < .05), and, to a lesser extent, smoking (P = .06), HDL cholesterol (P < .07), and elevated hematocrit (> or = 46%, P < .09) emerged as independent risk factors for SCD after adjustment for a wide range of factors. Diabetes was not found to be associated with SCD, and forced expiratory volume in 1 second, body mass index, white blood cell count, and antihypertensive drugs were not associated with risk of SCD after adjustment. When examined in relation to non-sudden IHD deaths and nonfatal myocardial infarction, elevated heart rate, heavy drinking, and arrhythmia emerged as factors that appear to be specific or particular to SCD. These three factors and age and blood cholesterol were associated with an increased risk of SCD in men both with and without preexisting IHD. Physical activity, systolic blood pressure, and current smoking were associated with SCD only in men without preexisting IHD. HDL cholesterol and hematocrit were strong predictors of SCD only in men with preexisting IHD.
Conclusions:
Three risk factors appear to be specific or particular to the risk of SCD, and these and other risk factors operate differently in patients with versus those without preexisting IHD. These findings have implications for the causes and prevention of SCD.