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ihd

ischaemic heart disease (IHD)

Epidemiology:

general points:

  • also referred to as coronary artery disease (CAD)
  • incidence of coronary events = rate of occurrence of totality of fatal & non-fatal events
  • strictly speaking incidence should refer only to 1st event not recurrences but these are often lumped together in which case should be referred to as event rates
  • mortality from coronary heart disease is usually measured as annual umber deaths per 100,000 pop.
  • case fatality = risk of death after an event (ie. proportion who die within a set period after an event)

USA:

  • 1 million deaths per year = 50% of all deaths
  • 160,000 deaths occurred in people < 65 yrs old (45% of all AMI's occur in this age group)
  • 2/3rds of sudden deaths ffrom IHD occur outside hospital & usually within 2hrs of onset of symptoms
  • >50% are women
  • 5 million years of potential life is lost per year due to cardiovascular disease & costs > $US100b/year
  • there has been a 54% reduction in age-adjusted mortality from IHD from 220/100,000 pop. in 1963 to 101/100,000 pop. in 1990:
    • 25% fall in incidence
    • 25% fall in case fatality rate:
    • 30% mortality pre-CCUs
    • 15% mortality post-CCUs
    • 12.5% mortality post-CCUs with emphasis on decreasing MVO2
    • 5% mortality with introduction of thrombolytic therapy
  • cocaine abuse:
    • accounts for ~25% of non-fatal AMI's in those aged 18-45yrs with peak age of 32yrs
    • relative risk of AMI is 24x during the 1st hour after use

Australia:

  • mortality rates per 100,000:
    • 1950-1970:
      • men aged 20-69:
        • all causes: ~700
        • all cardiovascular: ~350
        • coronary heart disease: ~230
        • stroke: ~50
      • women aged 20-69:
        • all causes: 460 declining to 380
        • all cardiovascular: 210 declining to 160
        • coronary heart disease: ~75
        • stroke: 75 declining to 40
    • since 1970 there has been a steady decline in mortality such that by 1994:
      • men aged 20-69:
        • all causes: 390 (46% fall from 1967)
        • all cardiovascular: ~100 (67% fall from 1967)
        • coronary heart disease: ~90 (69% fall from 1967)
        • stroke: ~15? (73% fall from 1967)
      • women aged 20-69:
        • all causes: ~230 (46% fall from 1967)
          • all cardiovascular: ~40 (71% fall from 1967)
          • coronary heart disease: ~25 (71% fall from 1967)
          • stroke: ~10 (77% fall from 1967)
  • 28 day AMI case fatality rates in Australia:
    • 31% in 1960's, 25% in 1970's, 18% in 1980's
    • under 65yrs: 10.7% 1984-6; 8.4% 1987-9; 7.5% 1990-2;

Risk factors for coronary artery disease:

  • these are essentially those for atherosclerosis and primary prevention
  • Emerging risk factors for ACS include:
    • C-reactive protein (reduced by statin therapy)
    • raised homocysteine
    • amyloid A
    • interleukin-6
    • low activity of interleukin-1 (raises LDL, 15% incr. risk IHD, also risk for AAA)
      • genetic
      • drugs such as anakinra
    • mercury
    • sleep-disordered breathing
    • coffee (only in slow-caffeine metabolisers!)
      • Intake of coffee was associated with an increased risk of nonfatal AMI only among individuals with slow caffeine metabolism (odds ratio 2.3 (CI 1.4-3.9) for those aged < 59yrs drinking 4 or more cups of coffee per day). ref
    • obesity (using waist-to-hip ratio not simply BMI).
    • Consumption of alcohol of any type 3-4 times a week is protective. ref

taking a family history:

  • consider:
    • number of relatives at risk & their sex, age & age at which they developed disease
    • whether another explanation for coronary disease (eg. smoking, diabetes) exists
  • when is a 'positive' FH really STRONG?
    • several of 1st degree relatives have been affected
    • disease developed at a young age (< 65yrs)
    • cases include females
    • affected persons didn't smoke
  • when is a 'negative' FH really PROTECTIVE?
    • family is large, yet few developed disease
    • most members lived to a ripe old age
    • no disease develops despite a large number of smokers
ihd.txt · Last modified: 2015/02/28 22:32 by gary1