Transcript Silent ischemia - Atorvaacademics.com

Silent ischemia
• W. William Heberden’s described in the 1770s of a new syndrome,
centering around pain in the left chest and named by him “angina
pectoris”.
• Heberden’s description of the symptoms has prevailed for
centuries, as if it were written in stone.
•Decades later, this “pain in the chest” was clarified as being induced
by myocardial ischemia at the time the patient experiences the pain.
Circulation..2002:1906-08
Silent ischemia
• James Herrick described in his historical treatise on acute
myocardial infarction in 1912 two of his six patients who
experienced no pain during their cardiac events.
Trans Assoc Am Phys.1912:100
• In the 1970s, several groups of investigators began to use
ambulatory monitoring of the ECG, and with this new
technique, they described that ST depression, a cardinal sign
of myocardial ischemia on the ECG, can occur in patients
with ischemic heart disease (IHD) without accompanying
pain.
Ambul And ECG monitoring : 1978:93-106
Why Silent Myocardial Ischemia Is
Painless In Some Individuals
• A defective warning mechanism - as the reason for the absence of
pain, stressing that sensibility to pain differs from patient to
patient.
J Am Coll Cardiol. 1983;340-45
•
Others suggested that a general decreased sensibility to pain is
present in clinically silent patients.
J Am Coll Cardiol; 1998:348-52
•
Intriguing observations have shown that there is a particular
biochemical pattern of inflammatory system activation (an
increased production of inflammatory cytokines) that explains the
lack of anginal symptoms in these patients.
J Am Coll Cardiol 2001;1895-1901
Clinical Relevance of Silent Ischemic Episodes
• Patients with IHD who have painful anginal attacks during a 24-hour
period are most probably having additional painless ischemic
episodes, usually triggered by physical exertion or mental stress.
Circulation. 2002; 1906-8
•
In clinical studies, as many as 90% of ischemic episodes were found
to be silent.
J Am Coll Cardiol.1998; 1627-34
• It has been shown that patients with ambulatory ischemia are more
likely to have multi vessel coronary disease than patients without
ambulatory ischemia
J Am Coll Cardiol.1997:1483-89
• Thus, it appears that anginal pain is a poor indicator for IHD because
it underestimates the frequency of significant ischemia.
• Episodes of documented ischemia, regardless of whether they are
symptomatic or silent, do have prognostic significance.
J Am Coll Cardiol. 2002: 1906-08
Silent Ischemia Diagnosis
• Ambulatory monitoring does provide meaningful information about
ischemia in IHD patients, as a potential test for those who are unable to
exercise, it can detect Prinzmetal’s variant angina and hidden arrhythmia
and assess the effectiveness of antiarrhythmic therapy.
Circulation. 1999: 886-93
•Because ambulatory monitoring does not appear to be useful for
screening or for primary detection of IHD in asymptomatic patients,
exercise testing remains the most important screening test for IHD.
Circulation. 2002: 1906-08
The Importance of Pain During
Exercise Testing
• Arthur Master, who introduced exercise testing in the 1930s for
detecting myocardial ischemia, tacitly accepted that the occurrence of
pain during his classic 2-step test was not a criterion for diagnosing IHD.
• For many decades,the presence or absence of pain during bicycle or
tread meal testing was neglected and usually not even noted on test
interpretation.
Circulation.2002: 1906-08
• The pendulum, however, has now swung to the other side; exerciseinduced silent ischemia was recently found to be a most powerful
predictor of IHD in men who presented with any of the standard
coronary risk factors.
J Am Coll Cardiol. 2001: 72-79
• Exercise testing can thus identify the high-risk men, even if
asymptomatic, who could benefit from risk reduction and preventive
measures.
Circulation.2002: 1906-08
The Importance of Pain During New
Myocardial Imaging Techniques
• Myocardial perfusion defects detected on stress thallium testing or
ventricular dysfunction seen on stress echo examinations are today
accepted as evidence for transient ischemia, despite the lack of both
accompanying ECG alterations and chest pain.
Circulation.2002: 1906-08
• These tests have provided the final proof for the existence of silent
myocardial ischemia and, most importantly, they also have shown that
the severity of ischemia detected by these methods is not correlated with
the presence or absence of accompanying pain.
Clinical Nuclear Cardiology. 1995
Myocardial Infarction Without Pain
•Myocardial infarction (MI) without concurrent chest pain was
described in the 1950s in the Framingham heart study.
Silent Myocardial Ischemia. 1998:47-53
• This possibility should be borne in mind not only by the physician
but also by the person who may potentially suffer a heart attack,
especially those with risk factors such as diabetes and high blood
pressure, since 20% to 60% of MIs are unrecognized by the patient
and are diagnosed only subsequently.
• Of these unrecognized infarctions, approximately half are truly
silent (ie, the patient is unable to recall any symptoms whatsoever).
Circulation.2002:
1906-08
• It is important to stress that the prognosis of patients with
silent and with recognized infarctions appears to be similar
both for 10-year survival and for subsequent heart failure.
Silent Myocardial Ischemia. 1998:47-53
Silent Ischemia and diabetes
• The overall prevalence of CAD among patients with
diabetes is higher than in non-diabetic patients and may be
as high as 55% among patients with diabetes.
Diabetes Care.
1979: 120-6
• Furthermore, CAD represents the leading cause of death
in patients with diabetes.
Diabetes Care.
1993: 2035-8
Silent Myocardial Ischemia
•Chest pain represents the “tip of the iceberg” in the
ischaemic cascade.
Swiss Med Wkly. 2001: 427-32
•When diabetics and non-diabetics without evidence of CAD
are screened for ischaemia, there is a higher incidence of
silent ischaemia in the former, 6.4–22% and 2.5–11%,
respectively.
Am J Cardiol.
1997: 134-9
Angina pectoris
Ischemia on ECG
Systolic Dysfunction
Diastolic Dysfunction
Metabolic Changes
Perfusion defect
ischemia
Why Silent Ischemia
• Pain response to ischemia is often blunted in diabetes.
•Patients who presented with silent ischemia and had a CAD at
coronary angiography for verification of CAD more often had
peripheral macroangiopathy and a higher prevalence of
retinopathy.
•No correlation was found between silent ischemia and duration
of diabetes, HbA1c level, renal status, or cardiovascular risk
factors except for family history of CAD.
Swiss Med
Wkly. 2001: 427-32
• Langer et al. evaluated the sympathetic innervation in diabetic
patients using metaiodobenzylguanidine (MIBG) imaging after
having concluded in another study that silent myocardial
ischemia in asymptomatic diabetic men occurred frequently & in
association with automatic dysfunction, suggesting that diabetic
nephropathy might be implicated in the mechanism of silent
Why silent Ischemia ?
• Altered perception of myocardial ischemia might result from
damage to the sensory innervation of the heart. Swiss Med Wkly.
2001: 427-32
•Hikita et al. Measured ß-endorphin levels during exercise &
compared diabetics with non diabetics.
Am J Cardiol.
1993: 140-3
•The ß- endorphin level &pain threshold were significantly
higher in non diabetic patients with silent ischemia than in
diabetics.
•When myocardial ischemia (whether silent or symptomatic)
was present during exercise testing, the long term survival
Why silent Ischaemia ?
•In general, it has been shown that cardiovascular mortality
rate is more than doubled in diabetic men & and raised than 4
fold in diabetic women, when compared with other non diabetic
counterpart.
JAMA. 1979:
2035-8
•When myocardial ischemia (whether silent or symptomatic )
was present during exercise testing , the long term survival
among diabetics were worse than that of non diabetics.
Swiss Med Wkly.
2001: 427-32
• For clinicians, whether & when to examine patients with
diabetics who have no clear evidence of CAD poses a difficult
question.
• In type I diabetics, who often present with out the traditional
Why silent Ischaemia ?
• Because type 1 diabetes often starts early in life, CAD can
occur as early as in the 3rd & 4th decade in life.
Diabetes Care. 1998: 1551-9
• In
contrast,type 2 patients frequently have many other risk
factors & usually present in the 5th or 6th decade of life or
later.
• Often, diabetes is first identified when the patient presents
with angina, MI, or heart failure.
Swiss Med
Wkly.2001:427-32
• Furthermore, diabetics with silent ischemia may present in an
atypical manner e.g. with symptoms of easily fatigability,
exertional dyspnoea, or indigestion.
Indications for testing patients with diabetes
Resting ECG suggestive of ischemia or infarction
• Peripheral or carotid occlusive arterial disease
• Sedentary lifestyle, age 35 years, and plans to
begin a vigorous exercise programme
• Two or more of the risk factors listed below in
addition to diabetes:
• Total cholesterol  6 .2 mmol/l, LDL 4.0 mmol/l, or HDL
<0.9
• Blood pressure >140/90 mm Hg
• Smoking
• Family history of premature coronary artery disease
• Positive micro/macroalbuminuria test
.
Cardiac testing algorithm for the asymptomatic diabetic patient.
MI or ischemia on ECG
and
or
ECG
abnormal ECG but no
clear evidence of ischemia
cerebral/peripheral
vascular disease
 1 risk factor
abnormal
or
2 risk factors
Routine follow
up
stress perfusion imaging
or
stress echo
exercise stress test
(if not limited by baseline
ECG or inability to exercise)
based on test results
+/–
coronary angiography
Follow up strategies after screening exercise test
Pre-test risk
normal
mildly
exercise test results
moderately
abnormal
abnormal
severely
abnormal
high
4–5 risk factors
moderate
2–3 risk factors
low
0–1 risk factors
++
+
+
+++
++++
++++
+++
+++
++++
+++
+++
++++
+ Routine follow-up
++ Close follow-up
+++ Imaging (myocardial perfusion SPECT or stress echo)
++++ Cardiology referral/possible coronary angiography
When initial exercise stress testing is done in asymptomatic diabetic patients, the
type of follow-up depends on the pretest risk and degree of abnormality on the
stress test. Normal follow-up indicates annual re-evaluation of symptoms and signs
of CAD and ECG. A repeat stress test should be considered in 3–5 years if clinical
status is unchanged. Close follow-up means shorter intervals between evaluation
MANAGEMENT
• Several questions remain unresolved regarding proper treatment of
silent ischemia.
•The management of diabetic patients with CAD requires a
multidisciplinary approach.
•Management of blood pressure and lipids, smoking cessation, and
routine use of aspirin are indicated for all patients with diabetes but
arguably will have an even greater impact on morbidity and mortality
in patients with ongoingischemia.
• When aspirin is not tolerated, other anti-platelet agents should be
considered, such as clopidogrel.
Clinical Diabetes. 2003: 5-9
Glycemic control in the management of
silent ischemia
• Glycemic control is the cornerstone for treating and preventing
diabeticmicrovascular complications such as retinopathy and
nephropathy.
• Improved glycemic control may also help to lower rates of
macrovascular complications such as cardiovascular events.
• Appropriate glycemic control includes medical nutrition therapy/meal
planning, exercise, and pharmacotherapy as needed.
Clinical Diabetes. 2003: 5-9
ß-blockers in the management of silent
Ischemia
• ß-blockers are arguably the most effective class of anti-anginal
medications and are a cornerstone of therapy in suppressing silent
ischemia.
• This class of medications has a favorable effect on myocardial
oxygen demand by reducing blood pressure and heart rate.
• ß- blockers reduce the duration and frequency of silent ischemic
episodes more than do other classes of anti-anginal drugs.
• Clinicians have been reluctant to use ß-blockers in diabetic patients
because of the potential dampening symptoms of hypoglycemia or
worsening of glycemic control.
• However, cardioselective ß-blockers should be considered in all
diabetic patients with CAD.
• ß-blockers are associated with prognostic benefits including fewer
cardiovascular complications, subsequent infarctions, and deaths,
particularly in patients with diabetes.
Clinical Diabetes. 2003: 5-9
ACE inhibitors in the management of
myocardial ischemia
•ACE inhibitors are known to reduce infarct size, limit myocardial
remodeling, and reduce mortality.
• In diabetic patients, they are also the treatment of choice for
proteinuria and hypertension.
•Proteinuria, in turn, is an indicator for diabetic nephropathy and
possibly for advanced atherosclerosis and cardiovascular disease.
Clinical Diabetes. 2003: 5-9
• Recent studies suggest that ARBs carry similar benefits.
Lancet .2002: 1004-10
CCBS in the management of silent
ischemia
• Calcium-channel blockers (CCBs) are also effective
pharmacotherapy. Similar to the ß-blockers, CCBs reduce the
duration and frequency of silent ischemia. This class of medications
may be prescribed when the maximal effect of ß-blockers has been
achieved or when ß-blockers are contraindicated or not tolerated.
Clinical Diabetes. 2003: 5-9
Nitrates in the management of silent
ischemia
• Nitrates may be used in oral or transferal routes with -blockers when
desirable suppression of silent ischemia is not achieved with ß-blockers
alone.
• The effect of chronic usage of nitrates is limited by tolerance.
•This limitation can be overcome by allowing an 8- to 10-hour nitratefree period daily.
Clinical Diabetes. 2003: 5-9
Psychological and emotional treatment in
the management of silent ischemia
• Treatment of psychological and emotional issues : It is important
because psychological stressors may also contribute to precipitating
silent ischemia.
•Recognizing and treating depression is of critical importance.
• Proper management of such stressors may indeed reduce
myocardial ischemia.
Clinical Diabetes. 2003: 5-9
Revascularisation in the management of
silent ischemia
• Revascularisation as a means of therapy for silent ischemia is not
well supported.
• Coronary revascularisation may be achieved surgically via
coronary artery bypass graft (CABG) or percutaneously via
percutaneous coronary intervention (PCI).
• CABG and PCI should be considered in high-risk patients who
display ongoing myocardial ischemia despite an adequate trial of
pharmacotherapy.
Clinical Diabetes. 2003: 5-9