Coronary stenoses I25.19

The effects of coronary stenosis in the form of angina pectoris were already described by Seneca about 2000 years ago. In 1768 two authors, Rougnon and Heberden, described the symptoms of an attack of angina pectoris. Until today there is a dispute about the priority of the first describer (Wagner 1985). The first revascularizing measures of coronary stenosis in the form of balloon dilatation were developed by the German cardiologist Andreas Gruntzig and first performed in 1977 ibid. (Lapp 2014). The first successful bypass operation was performed in 1964 by DeBakey and Denis Garrett in Houston. However, it was not published until 1973 (Mueller 2001). For this reason, Rene Favaloro, who performed the first bypass surgery in Cleveland in 1967, is mentioned in some publications (Gerabeb 2007).

Coronary stenosis is the narrowing of the coronary arteries (Lapp 2014). A significant stenosis can cause various changes in the myocardium. One speaks of a significant coronary stenosis when there is a 50% reduction in the vessel cross-section (Schroeder 2002). A reduction of the vessel diameter by 80 % may already reduce the coronary flow at rest and cause myocardial ischemia (Kasper 2015).

Gradual classification of coronary stenosis (American Heart Association):

Degree of stenosis ≤ 25: Here the first wall irregularities appear.

Degree of stenosis 25 - 50: Slight stenosis

Degree of stenosis 50 - 75: Moderate stenosis

Degree of stenosis 75 - 90: Higher grade stenosis

Degree of stenosis > 90: High grade stenosis

Degree of stenosis 100: Complete closure (Erdmann 2009)

Morphology of stenoses according to the criteria of AHA / ACC:

Type A stenosis:

• The length of the stenosis is ≤ 1 cm
• Concentric shape
• Smooth contours
• Easily accessible
• Stenosis with angulation < 45 degrees
• No or only little detection of lime
• No complete closure
• No stenosis of the ostium
• No thrombus detection
• Side branches are not affected

Stenosis type B:

• B 1: only one criterion is fulfilled
• B 2: 2 or more criteria are met
• Length of the stenosis is 1 - 2 cm
• Eccentric shape
• The vessel is meandering
• Stenosis with angulation between 45 degrees - 90 degrees
• Contour appears irregular
• Clearly visible calcifications
• Complete closure, which does not last longer than 3 months
• Detection of a significant side branch in the area of the stenosis that is not to be protected
• Degenerated venous bypass

Type C shorthand:

• C 1: only one criterion is fulfilled
• C 2: 2 or more criteria are met
• The length of the stenosis is > 2 cm
• The vessel is highly tortuous
• Stenosis with angulation of > 90 degrees
• Complete closure older than 3 months
• Detection of a significant side branch in the area of the stenosis that is not to be protected
• Degenerated venous bypass (Erdmann 2009)

A coronary stenosis is found significantly less frequently in women than in men. Investigations of accidental deaths of both sexes showed arteriosclerotic changes in women in all age groups between 20 and 85 years, which corresponded to a 10 to 15 years younger status in men (Weidemann 1987). According to the American Heart Association in 2005 and the Federal Statistical Office in 2004, arteriosclerosis is the most common fatal disease in western industrialised countries (Erdmann 2009). Patients requiring dialysis are particularly frequently affected by coronary stenosis. After the age of 50, coronary stenosis occurs in about 60 % to 65 % of patients. About half of these patients have no symptoms, especially if they also suffer from diabetes mellitus (Hörl 2004).

Pathophysiology: A coronary stenosis is initially caused by a damage of the coronary endothelium. This is triggered by certain risk factors or certain noxious agents (see below). Due to the damage of the endothelium, the surface of the inner wall of the vessel becomes irregular and fibromuscular plaques are deposited, which lead to the stenosis of the coronaries (Greten 2010). Due to this stenosis, the myocardium is no longer sufficiently supplied with blood (Greten 2010), which can lead to myocardial ischemia and ultimately to coronary heart disease (CHD) (Pinger 2019). In the majority of cases, coronary stenosis occurs in several branches simultaneously. Even if these are only moderate stenoses, they have a stronger effect than an isolated higher-grade stenosis (Barmeyer 2020).

The limit values for significant stenoses are given very differently in the literature (Pinger 2019). It can be assumed, however, that at physical rest the blood flow in the coronary arteries drops already at a 60% stenosis. Studies by K L Gould showed in 1978 that blood flow was reduced by half in an 80% coronary stenosis and by a quarter in a 90% stenosis (Barmeyer 2020).

The cause of the above-mentioned damage to the endothelium and thus coronary stenosis may be:

• LDL- cholesterol increase > 160 mg/dl
• HDL- Cholesterol reduction < 40 mg/dl
• Lipid metabolic disorders e.g. hypertriglyceridemia ≥ 150 mg/dl
• Hyperfibrinogenemia ≥ 3.5 g/l
• Diabetes mellitus with HbA1c values > 7
• Disturbance of glucose tolerance with fasting FC values ≥ 100 mg/dl
• arterial hypertension
• tobacco use
• Family disposition (in first-degree family members, occurrence of myocardial infarctionbefore the age of 55 [m] or before the age of 65 [w])
• Age > 55 years (m) or > 65 years (w)
• Adiposity with an abdominal girth of > 94 (m) or > 80 (w)
• Atherogenic Diet
• Low social status
• Lack of physical exercise
• Z. n. thoracic radio
• For heart transplantation (HTX)
• Obstructive sleep apnea
• Genetic changes (so far, 20 gene regions are known to be associated with an increased risk of myocardial infarction ) (Herold 2019)

In the case of an infarction event before the age of 30, the following causes should be excluded in particular:

• Family-conditioned fat metabolism disorders
• Thrombophilia (e.g. due to an antiphospholipid syndrome)
• hypothyroidism and hypercholesterolemia associated with it
• Vasculitides such as:
  • panarteritis nodosa
  • Kawasaki Syndrome
  • Takayasu arteritis
• Anomalies of the coronary vessels
• Diseases of the coronary arteries (after surgery of congenital vitilia)
• drug abuse of:
  • Cocaine
  • Marijuana
• Hyperviscosity syndrome, such as:
  • multiple myeloma
  • polycythaemia vera
  • Essential thrombocythemia (Herold 2019)

The clinical manifestation of coronary stenosis shows three main criteria:

• angina pectoris
• Myocardial infarction
• sudden cardiac death (Weidemann 1987)

ECG: The ECG shows changes in the ST segment in coronary stenosis. These can be ST elevations as well as ST depressions.

If new changes in the ST segment occur in patients, coronary stenosis is detectable in 90% of cases (Unger 1995).

Stress ECG

In cases of suspected coronary stenosis, an exercise ECG (ergometry) is still part of the initial diagnosis. However, it is becoming less and less important due to the continuous development of imaging.

According to the 2013 ESC, sensitivity is reported to be 45%-50%, with specificity ranging from 85%-90%.

(Pinger 2019)

For more details, see. Stress ECG or coronary artery disease.

Stress echocardiography: With stress echocardiography, coronary stenoses can only be detected when they are already significant, i.e., constricting more than 50% of the vessel lumen. In patients with single-vessel disease, stenoses are detectable in approximately 80%, and up to 90% in multivessel disease (Völler 2000).

Computed tomography: Coronary stenosis can be well visualized in MSCT- angiography (multislice computed tomography) due to contrast enhancement, where native MSCT- angiography, on the other hand, is more successful in visualizing and quantifying coronary calcifications (Dißmann 2016).

CT-Calcium- Scoring: While the CT- Calcium- Score does not allow visualization of the coronary stenosis itself, statements - independent of traditional risk factors - can be made about the cardiovascular risk (Dißmann 2016).

CT- coronary angiography: Under optimal conditions (slender patient, bradycardic sinus rhythm, optimized examination protocol), both calcified and non-calcified plaques can be visualized and thus coronary stenoses can be reliably detected or excluded (Dißmann 2016).

Coronary angiography: During coronary angiography, arthereosclerotic changes that do not significantly affect the vessel cross-section cannot be detected or not completely detected. However, by measuring fractional flow reserve, the functional relevance of coronary stenosis can be assessed (Bösner 2011).

There are different therapeutic approaches for coronary stenosis. The treatment or progression of the stenosis can be carried out by:

• elimination of the risk factors
• conservative therapy
• surgical procedure

Elimination of risk factors

The main risk factors are

• Hypercholesterolemia

The target value for total cholesterol should be < 175 mg/dl and for LDL cholesterol < 100 mg/dl. (For further details see "Internal therapy" P. 5 below)

• arterial hypertension

The target blood pressure should be 140 mmHg for systolic values ≤ and / or diastolic values of ≤ 90 mmHg. During self-measurement < 135 / 85 mmHg (Herold 2020)

• Diabestes mellitus

According to the recommendations of ESC 2013, an HbA1c target value of < 7.0 % (= 53 ml/l) should be aimed for (Pinger 2019 / Wehling 2005)

Other risk factors are:

• Nicotine abuse

Stopping smoking reduces the cardiovascular 10-year risk by up to 50% (Herold 2020). The reduction in mortality from nicotine withdrawal has been proven in studies. The NNT value (number needed to treat) is 22.

• Lack of aerobic physical activity

The reduction of mortality through corresponding activities has been confirmed in studies. In addition, physical activity can increase HDL cholesterol by 4.6%.

According to ESC 2013 ≥ the training should be done 3 times/week for 30 minutes. Even light physical exercise increases life expectancy by 3 years (Herold 2020).

• Weight control

Being overweight not only increases the risk of coronary disease, but also that of hypertension, diabetes mellitus and hyperlipidemia. The abdominal girth in men should ideally be ≤ 94 cm and in women ≤ 80 cm (Suter 2005). The ideal BMI value is between 20 - 25 kg/m2 (Pinger 2019).

With the medicinal treatment one tries:

• to reduce the myocardial oxygen demand by
  • reduction of contractility, heart rate and afterload
• to improve the myocardial oxygen supply by
  • Reduction of the vascular tone in the coronary arteries
  • Extension of the diastol duration (frequency reduction)
  • Reduction of left ventricular end-diastolic pressure (preload)
• reduce the risk of thrombotic coronary occlusion
• to lower the LDL- cholesterol (Renz- Polster 2008)

1st beta-blockers: Beta-blockers are among the first choice therapy. They can reduce the oxygen demand of the heart. Beta-blockers lead to a reduction in frequency of 20 % - 25 % (Wehling 2005). Caution is advised, however, in patients with chronic obstructive pulmonary disease, diabetes mellitus and PAD. There is a relative contraindication for these diseases, as they increase bronchial obstruction, reduce the warning signs of hypoglycemia (e.g. sweating, tachycardia) and increase the symptoms of claudication (Renz- Polster 2008). Therapy suggestion: e.g. Metoprolol 200 mg/d or Atenolol 100 mg/d (Wehling 2005)

2. calcium channel blockers (former name: calcium antagonists): Long-acting calcium channel blockers such as verapamil, amlodipine, etc. are second choice drugs. They lead to cardiac relief by reducing the afterload (Wehling 2005). They have also been proven to reduce morbidity (Renz- Polster 2008). Therapy suggestion: e.g. Verapamil 240 mg - 480 mg/d, unretarded in 3 - 4 single doses, retarded in 2 single doses (Stierle 2017).

Note: Preparations with short onset of action and short duration of action such as unretarded nifedipine lead to a strong reduction in blood pressure. In an acute attack of angina pectoris, the oxygen demand is reduced by lowering the preload and postload, thus weakening the symptoms of an attack of angina pectoris. The reduction in frequency is only in the range of approx. 5 % (Wehling 2005). However, nifedipine should be avoided in long-term therapy (Stierle 2017), as it is associated with increased mortality (Renz- Polster 2008).

3rd ACE inhibitors: ACE inhibitors reduce the pre- and post-load and also have an antiproliferative effect (Christ 2019). They should preferably be used in patients with the following concomitant diseases:

- Heart Failure

- diabetes mellitus

- arterial hypertension

The KHK lethality is demonstrably reduced (Renz- Polster 2008). Therapy suggestion: e.g. Ramipril Initial dose: 1 x 1.25 - 2.5 mg/d, then increase the dose. The maximum dose of 10 mg/d should not be exceeded (Stierle 2017).

4. antiplatelet therapy: Antiplatelet therapy is an important, if not the most important preventive drug. Therapy suggestion: ASS 100 mg/d or in case of intolerance (the far more expensive) clopidogrel 75 mg/d (Stierle 2017) (Wehling 2005).

5. cholesterol synthesis inhibitors (statins): The target value for total cholesterol is < 175 mg/dl and for LDL cholesterol < 100 mg/dl. These values cannot usually be achieved by a diet alone and an appropriate lifestyle (Renz- Polster 2008). Therapy suggestion: Simvastatin 20mg - 40 mg/d (Lundgren 2018)

6th nitrates: Nitrates have been used clinically for over 125 years. They reduce left ventricular end-diastolic volume and pressure, decrease myocardial wall tension and oxygen demand, also lead to dilatation of epicardial coronary vessels and increase blood flow in collateral vessels (Kasper 2015). Nitrates are used for the therapy of acute angina pectoris attacks and for its prophylaxis. Short-acting preparations such as nitroglycerine are rapidly absorbed through the mucous membranes. Recommended dosage: 1-2 sublingual strokes (1 spray corresponds to 0.4 mg) up to 3 times daily with a minimum interval of 5 minutes between each dose (Kasper 2015). Long-acting preparations include, for example, isosorbide dinitrate (ISDN). Dosage recommendation: 1 x / d 1 retard preparation with 20 mg - 120 mg oral

Nitrates only have a purely symptomatic effect. Prognosis and lethality are not affected. In order to counteract the development of tolerance, a nitrate-free interval of 8 to 10 hours should be observed.

The surgical treatment consists of revascularization of the stenosed vessels. The two standard procedures for this are percutaneous catheter intervention (PTCA or PCI [percutaneous coronary intervention] in the Anglo-Saxon world) and coronary bypass surgery (ACVB or CABG [coronary artery bypass graft] in the Anglo-Saxon world) (Stierle 2017).

Indications:

The indications for the individual procedures are partly dependent on the SYNTAX score: The syntax score is an angiographic score based on 9 anatomical criteria and can be used to make statements on perioperative risk assessment. In Europe, the European System for Cardiatic Operative Risk Evaluation (Euro- Score) is the most commonly used. The individual risk can be calculated using a web-based calculator (www.euroscore.org./calc.html). However, the Euro- SCORE overestimates the mortality risk in individual patient groups (Stierle 2017).

The recommendations according to the German Society for Cardiology, Heart and Circulation Research 2012 (ESC Pocket Guidelines) for generally stable patients and lesions for which both procedures are suitable and which have a low expected surgical mortality are as follows: (see also below the update of the syntax study of 2019)

1- GE or 2- GE without proximal LAD stenosis:

ACVB: IIb- C

PCI: I-C

1- GE or existing proximal LAD stenosis:

ACVB: I- A

PCI: I- A

2- GE with proximal LAD stenosis:

ACVB: I- B

PCI: I- C

Main stem stenosis left and syntax score ≤ 22:

ACVB: I- B

PCI: I- B

Main stem stenosis left and syntax score 23 - 32

ACVB: I- B

PCI: II a- B

Main stem stenosis left and syntax score ≥ 32

ACVB: I- B

PCI: III- B

3- GE and syntax score ≤ 22

ACVB: I- A

PCI: I- B

3- GE and syntax score 23 - 32

ACVB: I- A

PCI: III- B

3- GE and syntax score ≥ 32

ACVB: I- A

PCI: III- B (Stierle 2017)

Addendum: The COURAGE study published in 2007 already showed that PCI does not lead to a life-prolonged benefit in stable CHD. PCI is only indicated in stable CHD if there is a lack of self-control or if complications occur.

The following patients represent a classic indication for PCI:

• the symptomatic patient
• the patient with acute coronary syndrome (ACS) (Pachinger 2007)

However, the COURAGE study was criticized by advocates of the invasive strategy because of methodological weaknesses (Overbeck 2012).

Initial results of the ISCHEMIA study (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches), which was launched in 2012 and involves 8,518 patients (5,179 randomised), were presented at the congress of the American Heart Association (AHA) in Philadelphia in 11/2019.

One composite (consisting of cardiovascular death, myocardial infarction, resuscitation after cardiac arrest, heart failure or hospitalization for unstable angina) occurred in the first year:

• Patients with invasive treatment in 5.3
• Patients with drug treatment in 3.4

After 4 years a composite joined:

• Patients with invasive treatment in 13,3
• Patients with drug treatment in 15.5

The number of deaths was 6.5 % versus 6.4 %.

The study is to be continued for another 5 years, so that a final evaluation is still pending (Hochman 2019).

1 Percutaneous catheter intervention: PTCA (percutaneous transluminal coronary angioplasty) is a technique that dilates narrowed coronary vessels, such as balloon dilatation and stent placement. The term PCI (percutaneous coronary intervention), which is commonly used in the English-speaking world, is used synonymously (Bonzel 2008).

The standard method consists of a dilatation of the coronary vessels by means of a balloon catheter.

Drug-coated balloon catheters, so-called DCB, whose surface is coated with an antiproliferative drug, represent a further development (Stierle 2017).

Initially, stents were only used if the balloon dilatation did not lead to the expected result. In the meantime, depending on the center, approx. 80 % to 95 % of all PTCA are performed with stent implantation. As a result, the rate of stenoses and re-PTCA has been significantly reduced (Stierle 2017).

A distinction is made for the stents between the

• uncoated stents (bare metal stents = BMS)
• the stents coated with an antiproliferative drug, so-called drug-eluting stents or DES
• resorbable coronary vascular scaffolds so-called scaffolds, which are remodeled by the body after months and thus allow the restoration of vascular mobility and vascular function (Herold 2020).

Increased PTCA risks exist:

• higher age
• female sex
• Decrease of the systolic left ventricular function
• several vessels with a stenosis of > 70
• unstable angina pectoris
• Acute myocardial infarction < 24 h
• Performing the procedure under emergency conditions
• cardiogenic shock
• Heart Failure
• Accompanying diseases such as:
  • Mitral valve insufficiency > grade II
  • Diseases of the aortic valve
  • diabetes mellitus
  • peripheral AVC
  • Apoplexy
  • Creatine increase of > 2 mg %
  • dialysis patient
  • Hypercholesterolemia
  • intraluminal thrombus (Stierle 2017)

In addition to PTCA, there are other catheter methods which are only used for special indications and therefore have only limited significance:

• Rotational angioplasty, also called rotablation. This method is used for severely calcified stenoses or for outgoing stenoses
• Directional coronary atherectomy (DCA), which is used for ostial stenoses
• Ultrasonic angioplasty or ultrasonic thrombolysis
• Cutting balloon for the treatment of complex stenoses
• Laser- PCI is used, for example, for calcified stenosis (Herold 2020)

Severe cardiac or cerebral complications can occur if the patient has previously had:

• stable angina pectoris in < 0.5
• unstable angina pectoris up to 1 % (Herold 2020)

Possible periinterventional complications:

• Occurrence of a dissection of the coronary artery with acute coronary occlusion (occurs in about 7%). There are 3 possibilities of therapy:
  • Method of the 1st choice is the insertion of a stent. The success rate is 85%.
  • Emergency bypass surgery
  • conservative infarct therapy (intensive care)
• occurrence of subacute stent thrombosis (this occurs within the first month in 0.5% - 5% of cases)

CAVE: NSAIDs should not be administered in combination with ASS / ADP receptor antagonists (clopidogel).

• Restenosis can be found after a
  • Balloon dilatation in up to 40
  • Stent implantation < 30
  • after implantation of a coated stent (DES) < 10

Over 95% of re-stenoses occur within 6 months.

• intravascular embolization

Protection systems should be used in bypasses. The mortality rate of the intervention is < 0.1 % (Stierle 2017). The highest success rate of a percutaneous catheter intervention of >95 % is found in type A stenosis (classification of the degree of stenosis see above). For type B stenosis the success rate is 90 % to 95 % and for type C stenosis between 80 % and 85 % (Stierle 2017).

The rate of re-stenosis could be reduced to less than 10 % by the predominant use of stents. However, the delayed re- endothelialization of the stent has a disadvantageous effect, as the risk of subacute stent thromboses persists for a period of time that cannot be precisely quantified at present. Therefore, it is currently recommended to administer ASS 100 mg/d for life and, according to ESC guidelines, to additionally administer a thrombocyte aggregation inhibitor (P2Y12 antagonist), e.g. clopidogrel, for 6 months postoperatively (dosage recommendation: initially 300 mg p. o., then 75 mg - 150 mg/d [Stierle 2017])(Kasper 2015).

2. coronary bypass surgery (ACVB)

In the meantime, coronary bypass surgery can be performed classically or minimally invasively (Herold 2019).

a) Classic ACVB

It is performed via a sternotomy access and using a heart-lung machine. A distinction is made between different ways of bypass:

• Arterial bypass, for example:
  • LIMA (ITA) bypass. The coronary stenosis is bridged by the left internal thoracic artery (also known as internal mammary artery).
  • RIMA bypass. The coronary stenosis is bridged by means of the right internal thoracic artery.
  • A. radialis- Bypass
  • A. gastroepiploica bypass (rare)
• Venous bypass (ACVB or CABG in the English-speaking world) e.g.:
  • aortocoronary venous bypass (Herold 2020)
  • V. saphena magna (cannot be used if varicosis exists)
  • V. cephalica (mostly used in emergencies) (Stierle 2017)

b) Minimally invasive bypass surgery

There are different procedures for minimally invasive surgery:

• MIDCAP (minimally invasive direct coronary artery bypass)

After a left anterolateral, minimal thoracotomy, the ramus interventricularis anterior (RIVA) is revascularized by a left internal mammary artery bypass (LIMA bypass).

• TECAP (totally endoscopic coronary bypass)

Here, as the name suggests, work is carried out completely endoscopically.

• OPCAB (off- pump coronary artery bypass)

In this procedure, the operative revascularization of a multi-vascular disease is carried out via a partial or complete sternotomy without a heart-lung machine on the beating heart.

• Hybrid procedure

The hybrid process is a combination of MIDCAP and PCI with no bypass material (Herold 2019).

After a bypass operation, the patient should postoperatively take antiplatelet medication, e.g. ASS 100 mg/d. In case of intolerance, it is recommended to switch to antiplatelet inhibitors such as ADP receptor antagonists, e.g. clopidogel Adults/adolescents > 18 years: once/day 75 mg p.o. (Herold 2019).

Complications of ACVB:

• acute myocardial infarction
  • with new Q-wave occurs in 3.7
  • perioperative Q-wave infarction is found at 4.6
• CK- MB- increase occurs in 90 % of patients (in 6 % the increase is up to 10 times the normal value)
• apoplectic insult occurs in 1 % to 1.7 % of patients apoplexy rate in > 75 years old is 2.7 % within the first 30 days p.o.
• Atrial fibrillation (if this lasts longer than 24 h, anticoagulation should be carried out for 4 weeks due to the increased risk of an apoplexy; dosage recommendation: 1 x 20 mg / d (dose adjustment for liver and kidney dysfunction [Encke 2015])
• Mediastinitis with a mortality rate of 25% occurs at 1% - 4% (prophylaxis: preoperative administration of a cephalosporin e.g. cefuroxime 1.5 g/d or clindamycin 600 mg/d for 1 to 2 days {Rossaint 2019} and strict avoidance of hyperglycaemia [max. blood sugar value: 150 - 180 mg/dl])
• Renal insufficiency occurs at about 8%. Newly required dialysis occurs in about 1 % of patients and in > 75 years of age in > 3.1 % and 3.5 % respectively. In patients > 70 years of age with a preoperative creatinine value > 2.5 mg/dl, alternatives to ACVB surgery should therefore be considered (Pinger 2019).

Success rate:

• the survival rate after 5 years is 83 % - 92 %
• Survival rate after 10 years at approx. 81 %
• after 5 years 67 % - 83 % are symptom-free (under sole drug therapy the figure is 38 %)
• after 10 years, 47% - 63% are still free of symptoms (42% with drug therapy alone)
• bypass occlusion rate of the venous graft is:
  • after 1 month at 12
  • after 1 year 15 % - 31 % (Stierle 2017)
  • after 10 years between 29 % - 68 % (Herold 2019)
• after IMA (A. mammaria interna) - Bypass:
  • after 10 years at only 5 % - 10
• A. radialis bypass:
  • after 10 years between 17 % and 37 % (Herold 2019)
• after 10 years with IMA bypass on the LED, the bypass is closed in only 1 % of cases (pinger 2019)

Mortality:

• Hospital mortality is 1.1 % for elective procedures and 2.6 % after urgent surgery
• without or with main stem stenosis at 1.5 % and 2.5
• without or with diabetes mellitus at 1.6 % and 2.6
• after 3 months the mortality rate is 1 % to 2 % (Stierle 2017)
• compared to a venous bypass, 27% of patients die less within 15 years after using an A. mammaria bypass (Herold 2019)

Comparison of PTCA and bypass surgery: The risk is higher with bypass surgery in the early postoperative stage than with PTCA. In the further course of the disease, however, the bypass surgery shows an advantage in patients with complex or multiple stenoses (e.g. disease of the left main stem, triple-vessel disease) with regard to

• Occurrence of a myocardial infarction
• Need for new cardiological interventions
• Improving the quality of life
• lower overall mortality (according to syntax study) (Kasper 2015)

Syntax Study: At the congress in Paris in August 2019, the results of the 10-year study Syntax (Synergy between PTCA with TAXUS Drug-Eluting-Stent and Cardiac Surgery) with 1,800 patients were presented. In this study 93 % of the patients received PTCA and 95 % a bypass surgery.

The following results were found:

• no differences between PTCA and ACVB were found when using 1st generation stents
• there were no significant differences in mortality: after 10 years, mortality in the PTCA group was 27% and in the ACVB group 23.5%. (HR 1.17 and p=0.092)
• Patients with coronary 3-vascular disease showed worse results with PTCA. Here a bypass surgery should be preferred (151 vs. 113 patients, 27.7% vs. 20.6%, HR: 1.41, p=0.006)
• in diabetics treated with medication there was no significant difference between the two groups
• in patients with a left main stem stenosis there was no difference in the 10-year survival rate in both groups
• in patients with complex coronary disease (corresponding to a SYNTAX score of > 33) bypass surgery should be preferred (33.8% vs. 26.3%, HR: 1.41)

Conclusion: In patients with a SYNTAX score > 33 (www.euroscore.org/calc.html) and / or coronary artery disease the bypass surgery should be preferred (Vetrovec 2019 / Einecke 2019).

Current supplement:

The results of the EXCEL study, which was published in November 2019 in the New England Journal of Medicine and started in 2010, show stent and bypass as equivalent therapies in the case of main stem disease. This result triggered a discussion among cardiologists and heart surgeons.

As a result, a BBC Newsnight survey in December 2019 published mortality results 5 years after the completion of the EXCEL study. The mortality was:

• 13 % after stent implantation
• 10 % after bypass surgery

In addition, unpublished data from the study showed an 80 % higher infarction rate in the PCI group.

The European Association of Cardio- Thoracic Surgery (EACTS) is currently reviewing the clinical guidelines. These were revised only last year on the basis of the 3-year results of the EXCELL study.

(Stone 2019; Holm 2019; Cohen 2019)

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