Nstemi I21.4

A NSTEMI (Non- ST- elevation myocardial infarction) is the occurrence of an acute myocardial infarction in which the persistent ST- elevation is missing. The increase of troponin and CK- MB is present, as is necrosis of the myocardium.

Note: In this article only those things which are important for the NSTEMI are mentioned. For more detailed information on myocardial infarction, please consult the article on acute myocardial infarction.

NSTEMI belongs to the group of acute coronary syndromesalong with STEMI and unstable angina pectoris.

The NSTEMI occurs more frequently than the STEMI (15 % - 20 % vs 5 % - 10 %) (Roffi 2015) The annual frequency is 3 per 1,000 inhabitants (Pinger 2019).

In NSTEMI there is partial necrosis of the respective affected myocardium with embolization by a thrombus in case of plaque rupture or subtotal vascular stenosis (Hamm 2014).

For detailed symptoms see myocardial infarction

According to the MONICA study (Keil 2005), the typical infarction symptoms only occur in about 40% of all infarctions. These typical symptoms are:

• Intense and persistent angina pectoris pain, which can hardly be influenced by rest or nitro administration (in contrast to stable angina pectoris)
• the retrosternal pain may radiate in
• the neck / nape of the neck
• Lower jaw
• Teeth
• Shoulder area
• both (!) arms (with focus on the ulnar sides of the forearms), which can radiate into the ulnar fingertips
• Pain below the xyphoid in the epigastrium (rarely also below the navel)
• typically the region of the trapezius muscle remains painless (pain in this area is typical of pericarditis) (Kasper 2015)
• Cardiac arrhythmias in the form of ventricular tachycardia, ventricular fibrillation, AV blockages occur in approx. 95% of cases
• often drop in blood pressure with cerebral dysfunction
• Symptoms of left heart failure with shortness of breath occur in about 33
• in right ventricular infarction:
• lack of congestion in the lungs
• Neck vein stasis
• often bradycardia (Herold 2020)
• Weld eruption
• cold extremities
• Increase of body temperature up to 38 degrees C (Kasper 2015)

Approximately 5% of patients experience reproducible chest pain triggered by local pressure (Pinger 2019).

Inspection and palpation: Typically, patients hold the clenched fist in the middle of the sternum (Levine's sign) when describing pain, the hand is placed flat on the sternum or both hands, fingertips facing each other, are placed on the sternum from the side to indicate belt-shaped tightness.

The sensitivity to cardiac pain is about 80%, the specificity is about 49% (Edmondstone 1995)

ECG: The NSTEMI lacks the ST segment elevation typical of the STEMI. It may be present:

• in 20 % - 25 % reductions of the ST segment, which can persist for several days (Kasper 2015)
• transient ST- elevations
• T- waves can be normal or negative (Stierle 2017)

A NSTEMI mainly affects the area of the left chamber. From the ECG with derivations typical for an infarct, the exact area of the occlusion can practically not be localized, because the coronaries are variable and the type of supply is not known (Herold 2020). The following classification is a guide to the location of the infarct:

• RIVA proximal:
  • large infarct in the area of the anterior wall
  • V1 to V6, aVL, I as direct infarction signs
  • (II), III, aVF as indirect infarction signs
• RIVA after departure of the diagonal branches:
  • anteroseptic infarction
  • V1 to V4, aVL, I as direct infarction signs
  • (II), III, aVF as indirect infarction signs
• diagonal branch:
  • Lateral Infarction
  • V5 to V7, aVL, I as direct infarction signs
  • no indirect infarction signs
• posterolateral branch:
  • Posterolateral Infarction
  • V5 to V6, aVF, II, III as direct infarction signs
  • V1 to V3, aVL, I as indirect infarction signs
• RCX:
  • apoplectic fit posterior to the posterior wall
  • V7 to V9, aVF, III as direct infarction signs
  • V 1 to V2 as indirect infarction signs
• RCA:
  • inferior posterior wall infarction / right ventricular infarction
  • V1 , V 3r to V6r, aVF, II, III as direct infarction signs
  • V1 to V3 as indirect infarct signs

Troponin T:

• at NSTEMI ≥ 0.01 to ≤ 1.0
• CK- MB- Increase (Stierle 2017)

The probability of a NSTEMI can be determined with the help of highly sensitive troponin assays by so-called 1- h- or 3- h- exclusion logarithms (0- h / 1 h or 3 h) as "rule in" or "rule out". The negative predictive value lies between 98 % - 100 %, the positive predictive value between 75 % and 80 % (Mehilli 2016).

Unstable angina pectoris (differentiation by highly sensitive troponin assays possible, see "Laboratory"). Further differential diagnoses: see "myocardial infarction" and "acute coronary syndrome".

Patients with a clear NSTEMI should be immediately admitted to coronary angiography according to ACC / AHA (2016). The further therapeutic procedure should be decided depending on the findings of the coronary angiography (Pinger 2019). Thrombolysis is not performed in patients with a NSTEMI (Stierle 2017).

For detailed information on the therapy see Acute myocardial infarction.

The 30-day mortality in NSTEMI is 10.4 %, the 6-month lethality 18.7 % (Stierle 2017).

After a NSTEMI with a low risk of cardiac arrhythmia (criteria: hemodynamically stable, no severe arrhythmias, left ventricular ejection fraction > 40 %, successful reperfusion) the patient should be monitored for 24 h. All other patients require monitoring for > 24 h (Roffi 2015).

Bed rest is recommended for 12 - 24 h or until the CK value drops significantly. In the case of a very small NSTEMI, discharge from inpatient treatment is possible after 72 h at the earliest, provided early rehabilitation is organised (Stierle 2017).

The integration into everyday or professional life can be carried out gradually. The patient should be encouraged to participate in an outpatient heart group (Herold 2020).

Initially, the prognosis of a NSTEMI in the acute stage is better than that of STEMI, since there is a smaller extent of myocardial damage in NSTEMI. In the further course, however, the prognosis is equal to that of a STEMI (Hamm 2014).
In patients with Z. n. NSTEMI, angina pectoris recurs in up to 20% of patients (Stierle 2017).

The prognosis can be improved by the following general measures:

• adherence to abstinence from nicotine
• Mediterranean diet
• Aerobic physical exercise ≥ 3 times a week for 30 - 45 minutes
• Optimal control of any existing arterial hypertension
• Optimal control of any diabetes mellitus that may be present
• Regular flu vaccination once a year (Herold 2020)

The prognosis can be improved by the following medicinal and therapeutic measures:

• Beta-blockers without intrinsic activity (these lead to a decrease in cardiac output. Prolonged use leads to a reduction in heart rate, cardiac output and plasma renin activity. This reduces the risk of reinfarction and heart failure. There is also a reduction in rhythmogenic deaths). Dosage recommendation: Initially only 1/10 of the target dose should be administered. Increase the target dose very slowly and under constant clinical monitoring of symptoms, weight and auscultation findings. Increase the dose every 14 days. Adjustment usually takes several months.
  • Bisoprolol 1 x 23, 75 mg / d, target dose 2 x 100 mg / d
  • Carvedilol 3 x 3.125 mg / d, target dose 2 x 25 mg / d (Herold 2020 / Braun 2018 / Rietbrock 1991 / )
  • Platelet aggregation inhibitors
• DAPT: dual antiplatelet therapy (DAPT) should be given for 1 year after a NSTEMI. Dosage recommendation:
  • Acetylsalicylic acid: ASA 75 mg - 100 mg /d for life (Herold 2020)
  • plus clopidogrel: initial 300 - 600 mg, then 75 mg / d for 1 year
  • or
  • Ticagrelor: initial 180 mg, then 2 x 90 mg / d (contraindications: history of intracranial bleeding, current bleeding)
  • or
  • Prasugrel: initial 60 mg, then 10 mg / d (contraindications: history of intracranial bleeding, ischemic insult, transient ischemic attack, current bleeding; prasugrel is not used in patients ≥ 75 years of age or with a body weight ≤ 60 kg)
• Oral anticoagulation in addition to DAPT: If atrial fibrillation, a left ventricular thrombus or the need to insert a heart valve occurs, oral anticoagulation should also be given (see thrombosis prophylaxis) (Herold 2020)
• Cholesterol-lowering drugs / statins. Dosage recommendation:
  • Pravastatin: 40 - 80 mg / d (Pinger 2019): The target value for LDL cholesterol should be < 70 mg / dl. If this cannot be achieved, additional
  • Ezetimibe or PCSK9 inhibitors should be given. Dosage recommendation: ezetimibe 10 mg / d; PCSK9 inhibitor e.g. evolocumab 10 mg / d (Herold 2020 / Schwabe 2016)
• ACE inhibitors: After a NSTEMI, the heart undergoes structural remodeling and adaptation processes, so-called "remodeling". These changes can lead to hypertrophy, expansion of the myocardial scar and dilatation of the left ventricle, which significantly worsen the further prognosis. ACE inhibitors make it possible to halt this process and thus reduce overall mortality, as several studies (e.g. SAVE, TRACE, AIRE, etc.) have shown (Herold 2020). Dosage recommendation:
  • Captopril: 6.25 mg initially, 2 h later 12.5 mg, 12 h later 25 mg, then 2 x 50 mg / d or:
  • Ramipril 2 x 2.5 mg, then 2 x 5 mg / d orally (Pinger 2019). If the patient has intolerances such as coughing or contraindications,:
  • Sartans (AT1 blockers) can be switched. Dosage recommendation: Valsartan: 20 mg in 4 stages to 2 x 160 mg as a maintenance dose (Herold 2020)
• Aldosterone receptor antagonist: If the patient's heart failure persists despite treatment with beta-blockers and ACE inhibitors (or AT1 blockers) or if there is a reduction in left ventricular ejection fraction (LV EF) of < 35%, the administration of an aldosterone receptor antagonist is recommended. Dosage recommendation:
  • Spironolactone: starting dose: 1 x 25 mg, target dose 2 x 25 mg - 50 mg (Herold 2020 / Aktories 2017).

Cardiac resynchronization therapy: Cardiac resynchronization therapy should be given for:

• - a left bundle branch block-like QRS complex > 120 ms - 150 ms
• - an LV EF ≤ 35 %
• - progressive heart failure (NYHA > II) despite optimal drug therapy (Herold 2020)

Implantable defibrillator (ICD): If symptomatic heart failure NYHA II - III or a reduced left ventricular ejection fraction ≤ 35 % persists after optimal drug treatment for > 40 days, an ICD is indicated (Herold 2020).

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