ACUTE CORONARY SYNDROMESPart I

Definition

Acute coronary syndrome (ACS) describes a spectrum of clinical conditions ranging from ST segment elevation myocardial infarction (STEMI) to non-ST segment elevation myocardial infarction (NSTEMI) and unstable angina (ACS without enzyme or marker release)

WHO definition of MI (old definition)

WHO defined MI by a combination of two of three characteristics: typical symptoms (e.g., chest discomfort), enzyme rise and a typical ECG pattern involving the development of Q waves

The revised definition of MI (2000)

The joint ESC/ACC/AHA consensus redefined MI as any amount of myocardial necrosis caused by ischemia

As a result of this more sensitive definition approximately 25-30% that would previously have been classified as UA now fulfill the criteria for MI

Criteria for acute, evolving or recent MI (1) Typical rise and gradual fall (troponin) or more rapid rise

and fall (CK-MB) of biochemical markers of myocardial necrosis with at least one of the following:

(a) ischemic symptoms; (b) development of pathologic Q waves on the ECG; (c) ECG changes indicative of ischemia (ST segment elevation or

depression); (d) coronary artery intervention (e.g., coronary angioplasty).

(2) Pathologic findings of an acute MI.

Criteria for established MI Any one of the following criteria satisfies the diagnosis for

established MI:

(1) Development of new pathologic Q waves on serial ECGs. The patient may or may not remember previous symptoms. Biochemical markers of myocardial necrosis may have normalized, depending on the length of time that has passed since the infarct developed.

(2) Pathologic findings of a healed or healing MI.

Q1

MI has been redefined as any amount of myocardial necrosis caused by ischemia

A. True B. False

Q1

MI has been redefined as any amount of myocardial necrosis caused by ischemia

A. True B. False

Q2

In a patient with ACS, increased cardiac troponin levels establish the diagnosis of NSTEMI, whereas normal cardiac troponin levels establish the diagnosis of ………..

A. Ischemia B. Cardiac injury C. Unstable angina D. Coronary stenosis

Q2 Increased cardiac troponin levels establish the

diagnosis of NSTEMI, whereas normal cardiac troponin levels establish the diagnosis of ………..

A. Ischemia B. Cardiac injury C. Unstable angina D. Coronary stenosis

Of those who present with symptoms consistent with MI, up to 30% of patients with non-ST elevation on ECG who would otherwise have been diagnosed with UA, actually have MI based on cardiac troponin measurements

Impact of ACS

The consequences of ACS are not benign. Among those who survive to reach hospital alive,

approximately

12% of patients with STEMI 13% of those with NSTEMI 8% of patients with UA

will die in succeeding 6 months (GRACE registry)

Ten Global Risk Factors Contributing to Death Globally

(World Health Report 2002)

Childhood and maternal underweight

Unsafe sex

Elevated blood pressure - 7.1 million deaths

Tobacco - about 4.9 million deaths

Unhealthy alcohol use

Unsafe water, sanitation and hygiene

High cholesterol - 4.4 million deaths (7.9% of total)

Indoor smoke from solid fuels

Iron deficiency

Overweight/obesity

Ten Global Risk Factors Contributing to Death Globally

(World Health Report 2002)

Childhood and maternal underweight

Unsafe sex

Elevated blood pressure - 7.1 million deaths

Tobacco - about 4.9 million deaths

Unhealthy alcohol use

Unsafe water, sanitation and hygiene

High cholesterol - 4.4 million deaths (7.9% of total)

Indoor smoke from solid fuels

Iron deficiency

Overweight/obesity

Ten Global Risk Factors Contributing to Death Globally

(World Health Report 2002)

Childhood and maternal underweight

Unsafe sex

Elevated blood pressure - 7.1 million deaths

Tobacco - about 4.9 million deaths

Unhealthy alcohol use

Unsafe water, sanitation and hygiene

High cholesterol - 4.4 million deaths (7.9% of total)

Indoor smoke from solid fuels

Iron deficiency

Overweight/obesity

Ten Global Risk Factors Contributing to Death Globally

(World Health Report 2002)

Childhood and maternal underweight

Unsafe sex

Elevated blood pressure - 7.1 million deaths

Tobacco - about 4.9 million deaths

Unhealthy alcohol use

Unsafe water, sanitation and hygiene

High cholesterol - 4.4 million deaths (7.9% of total)

Indoor smoke from solid fuels

Iron deficiency

Overweight/obesity

Ten Global Risk Factors Contributing to Death Globally

(World Health Report 2002)

Childhood and maternal underweight

Unsafe sex

Elevated blood pressure - 7.1 million deaths

Tobacco - about 4.9 million deaths

Unhealthy alcohol use

Unsafe water, sanitation and hygiene

High cholesterol - 4.4 million deaths (7.9% of total)

Indoor smoke from solid fuels

Iron deficiency

Overweight/obesity

Establishing a working diagnosis

A working diagnosis is based upon the presence of

- a typical clinical syndrome (either rest pain or a crescendo pattern of ischaemic pain on minimal exertion)

plus

- ECG changes: ST segment elevation ACS or non-ST segment elevation ACS (ST depression, transient elevation, or T wave inversion)

Markers of myocyte injury may not be elevated on initial presentation if less than 4-6 hours have elapsed from the onset of ischaemia (repeat assay following an initially negative measurement is required !!!)

Urgent management should not be delayed awaiting the results of enzyme essays !

A sequence of immediate decisions is required:

- ACS or not, based on clinical and ECG (± Echo ) features

- Candidate for emergency reperfusion, PCI or not - ST segment elevation or true posterior MI or acute LBBB

- Low or high risk non-ST elevation ACS

ECGThree “I”

- Ischemia (T-wave changes);

- Injury (ST-T changes):

subendocardial ( ST); subepicardial, transmural ( ST);

- Infarction (necrosis): pathologic Q-wave(> 25 % di R, >0.03 s)

Localisation(ECG leads)

• V1-V3: antero-septal zone;

• V4: apex;

• V5-V6: lateral wall (middle and apical parts);

• I, aVL: lateral wall (basal part);• II, III, AVF: inferior wall;

• V1-V2: posterior wall (infero-basal)

Cardiac Biomarkers

1. MI is diagnosed when blood levels of sensitive and specific biomarkers, such as cardiac troponin (I or T) and CK-MB (mass assay) are increased to values greater than 99% of a normal reference population (with less than 10% coefficient of variation of the assay)

2. These biomarkers reflect myocardial damage, but do not indicate its mechanism

3. ASAT, LDH isoenzymes should not be used to diagnose myocardial damage

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