• angiography often does not demonstrate plaque
rupture with associated thrombus.
Once high-sensitivity cardiac troponin assays
become widespread, one challenge will be distinguishing ACS from biological processes that also
cause changes in troponin. The prototypical example is in the setting of acute HF where you can
see a rise and fall of troponin that is not indicative
of ACS. As Dr. Jaffe explained, “There is going to
be a time where almost every patient with acute
heart failure will have a rising pattern of cardiac
troponin, so they will have met the criteria in
terms of showing a rise and or a fall in troponin
but they are not patients we should say are having
a myocardial infarction.”
TREATMENT: UNCLEAR
If a type 2 MI is suspected, the problem then
becomes what do you do about? At this time, the
third universal definition authors admit there is
a dearth of information on which to base clinical
decisions in this setting.
Cardiac catheterization almost certainly is associated with significant risk in such critically ill
patients, as is antithrombotic therapy.
Often, beta-blockers, nitrates, and low-dose
aspirin are given, but without strong evidence
indicating that this is beneficial. Clinical research
involving patients with type 2 MI or myocardial
injury is needed desperately to assist in differentiating these entities and determining what, if any,
specific therapy is indicated.
REFERENCES:
1. Thygesen K, Alpert JS, Jaffe AS, et al. J Am Coll Cardiol.
2012;60:1581-98. http://content.onlinejacc.org/article.
aspx?articleid=1367084
2. Alpert JS, Thygesen K. Circulation.2006;114:757-8.
3. Alpert JS, Thygesen K; on behalf of the Joint ESC/ACC
Committee. J Am Coll Cardiol. 2000; 36: 959-69. http://
content.onlinejacc.org/article.aspx?articleid=1126658
4. Thygesen K, Alpert JS, White HD. J Am Coll Cardiol.
2007;50:2173-95. http://content.onlinejacc.org/article.
aspx?articleid=1138690
5. Alpert JS, Thygesen KA, White HD, Jaffe AS. Am J Med.
2014;127:105-8.
Take-aways
• Distinguishing type 1 from type 2 MI has been the
subject of considerable clinical discussion and
confusion.
• A type 1 MI is usually the result of atherosclerotic
CAD with thrombotic coronary arterial obstruction
secondary to atherosclerotic plaque rupture,
ulceration, fissuring, or dissection, causing
coronary arterial obstruction with resultant
myocardial ischemia and necrosis.
• Patients with a type 2 MI do not have
atherosclerotic plaque rupture. In this latter group
of patients, myocardial necrosis occurs because
of an increase in myocardial oxygen demand or a
decrease in myocardial blood flow.
CardioSource.org/CSWN
When Does Obesity Shorten Life Expectancy?
T
he increasing prevalence of overweight and
obesity is alarming given their association
with death, disability, and disease. However,
it is difficult to estimate the public health impact of
excess weight because of its complex interactions
with age, smoking, and obesity-related risk factors
such as diabetes, hypertension, and lipid disorders.
Even family history seems to play a role.
In a 50-year prospective study of Framingham
participants, investigators determined that being
obese when you are age 40 diminishes life expectancy by about 7 years.1 For obese people who
smoke, the prognosis is even worse: they typically
die 13-and-a-half years before their time.
Framingham data also tell us that measuring
the total effect of obesity by combining its level
(body mass index [BMI] units above 29 kg/m2)
multiplied by the duration of obesity into a single
metric of “obese-years” is a stronger predictor for
the risk of CVD compared to using duration of
obesity or level of obesity alone. Recently, investigators observed a clear dose-response relationship
between obese-years and risk of CVD. A stronger
effect was found in males than in females.2
This is especially alarming given the increasing
incidence of overweight and obesity in children. Early
in 2014, investigators reported data from the Early
Childhood Longitudinal Study, a prospective cohort
of 7,738 participants who were in kindergarten in the
United States in 1998.3 Fully 12.4% of kids entering
kindergarten were obese and another 14.9% were
overweight. While some of these kids “grew into” more
normal weights, subsequent incident obesity between
the ages of 5 and 14 occurred primarily among those
children who had entered kindergarten overweight.
DRAMATIC REDUCTION IN LIFE EXPECTANCY
In the summer of 2014, the NIH reported the results
of a study evaluating the risk of premature death associated with extreme obesity. In the U.S., 6% of adults
are now classified as extremely obese, which, for a
person of average height, is more than 100 pounds
over the recommended range of normal weight.
Investigators pooled data from 20 large studies of people from three countries.4 The final
sample included 9,564 extremely obese adults
and 304,001 healthy-weight adults, making it the
largest-ever study of its kind.
Overall risk of mortality as well as risk of
mortality from most major health causes rose continuously with increasing BMI within the class III
obesity (BMI 40 to 59 kg/m) group. Years of life lost
ranged from 6.5 years for participants with a BMI
of 40 to 44.9 to 13.7 years for a BMI of 55 to 59.9.
To provide context, the number of years of life lost
for class III obesity was equal or higher than that
of current (versus never) cigarette smokers among
normal-weight participants in the same study.
According to Patricia Hartge, ScD, senior
author of the study, “Given our findings, it appears
that class III obesity is increasing and may soon
emerge as a major cause of early death in this and
other countries worldwide.”
THERE IS GOOD NEWS
Robert H. Eckel, MD, said the data really do illustrate
the dangers of extreme obesity, but the good news is
that being overweight, defined as a BMI of 25.0 to 29.9,
does not influence life expectancy “one iota.” However,
as BMI increases, particularly once it is beyond 35, “it is
pretty clear that obesity impacts life expectancy.” Most
of this increased mortality is CVD-related. So, if you are
looking for cutoffs that matter in terms of mortality, a
BMI > 35 appears to be an important one.
The exception: age 70 years and older. “There’s
something about extra b