**4. Prognostic role of initial and residual SYNTAX score in patients with ST‐segment elevation myocardial infarction after primary percutaneous coronary intervention**

#### **4.1. Methods**

We recruited 327 consecutive patients and carried out a single‐center registry study. The study was performed in accordance with the principles of Good Clinical Practice and the Declaration of Helsinki. The local ethical committee approved the study and all the participants provided written informed consent after receiving a full explanation of the study. Criteria of inclusion were (1) hospital admission within 12 h of STEMI onset requiring the performance of primary PCI; (2) MVCAD defined as hemodynamically significant (≥70%) stenosis of two or more coronary arteries; (3) technical ability to per‐ form PCI. Criteria of exclusion were (1) acute heart failure Killip class III‐IV (pulmonary edema and cardiogenic shock); (2) left main coronary artery stenosis ≥50%. Before PCI, all patients received a loading dose of acetylsalicylic acid (250–500 mg) and clopidogrel (600 mg). Successful PCI was defined as the reduction of stenosis to <20% and a TIMI flow grade 3. After the PCI, all the patients received aspirin, statins, and clopidogrel during 1 year of follow‐up.

We first evaluated the prognostic value of initial SYNTAX score that was calculated before PCI. Patients were divided into two groups depending on the severity of coronary lesions: SYNTAX ≤ 22 points (n = 213) and SYNTAX ≥ 23 points (n = 114). We then evaluated resid‐ ual SYNTAX score that was calculated after PCI. Likewise, patients were stratified into two groups: SYNTAX ≤ 8 points (n = 243) and SYNTAX ≥ 9 points (n = 74). The SYNTAX score was assessed using a calculator (http://www.rnoik.ru/files/syntax/index.html).

#### **4.2. Results**

#### *4.2.1. Baseline characteristics*

**Table 4** demonstrates the baseline clinical and demographic characteristics in study groups. As shown, patients with severe coronary atherosclerosis (SYNTAX ≥ 23**)** were characterized by (1) older age; (2) decreased left ventricular ejection fraction (LVEF); (3) more frequent past med‐ ical history of MI; (4) more severe acute heart failure compared to those with SYNTAX ≤ 22.

**Table 5** shows a comparison of clinical and demographic characteristics of patients after pri‐ mary PCI. Patients with SYNTAX ≥ 9 were characterized by (1) older age; (2) higher prevalence of females; (3) decreased LVEF; (4) more frequent past medical history of MI and peripheral artery disease compared to those with SYNTAX ≤ 8.


**Table 4.** Patient clinical and demographic features (initial SYNTAX score groups).


**Table 5.** Patient clinical and demographic features (residual SYNTAX score groups).

Analysis of the angiographic parameters and features of revascularization revealed a direct relationship between the initial SYNTAX ≥ 23 and residual SYNTAX ≥ 9 (**Table 3**). In com‐ parison with residual SYNTAX ≤ 8 patients, those with SYNTAX ≥ 9 patients had (1) a higher prevalence of initial SYNTAX ≥ 23; (2) more frequent three‐vessel disease; (3) more rare use of multivessel stenting strategy; (4) less percentage of successful PCI in IRA (**Table 6**).

#### *4.2.2. Events*

**Variables Patients (n = 327) Р value**

**Table 4** demonstrates the baseline clinical and demographic characteristics in study groups. As shown, patients with severe coronary atherosclerosis (SYNTAX ≥ 23**)** were characterized by (1) older age; (2) decreased left ventricular ejection fraction (LVEF); (3) more frequent past med‐ ical history of MI; (4) more severe acute heart failure compared to those with SYNTAX ≤ 22.

**Table 5** shows a comparison of clinical and demographic characteristics of patients after pri‐ mary PCI. Patients with SYNTAX ≥ 9 were characterized by (1) older age; (2) higher prevalence of females; (3) decreased LVEF; (4) more frequent past medical history of MI and peripheral

Age, years 59.1 ± 9.9 60.9 ± 10.6 0.08 Male gender 142 66.6 74 64.9 0.8 LVEF, % 52.5 ± 7.2 48.4 ± 8.8 0.000009 Arterial hypertension 188 88.3 103 90.3 0.7 Diabetes mellitus 47 22 20 17.5 0.4 Peripheral artery disease 56 26.3 33 28.9 0.7 Past medical history of MI 21 9.8 29 25.4 0.0001 Past medical history of stroke 8 3.7 3 2.6 0.8 Acute heart failure (Killip class II) 17 7.9 21 18.4 0.009

**Variables Patients (n = 317) Р value**

Age, years 58.8 ± 9.9 63.1 ± 10.6 0.001 Male 76 31.3 34 55.9 0.03 LVEF, % 51.4 ± 7.6 49.2 ± 9.2 0.08 Hypertension 218 89.7 68 91.9 0.7 Diabetes mellitus 45 18.5 20 27 0.2 Peripheral artery disease 59 24.3 28 37.8 0.03 Previous MI 31 12.8 17 23 0.05 Acute heart failure (Killip II) 29 11.9 10 13.5 0.9

**Residual SYNTAX ≤ 8 (n = 243) Residual SYNTAX ≥ 9 (n = 74)**

**n % n %**

**Table 4.** Patient clinical and demographic features (initial SYNTAX score groups).

**Table 5.** Patient clinical and demographic features (residual SYNTAX score groups).

artery disease compared to those with SYNTAX ≤ 8.

**4.2. Results**

26 Interventional Cardiology

*4.2.1. Baseline characteristics*

**Initial SYNTAX ≤ 22 (n = 213) Initial SYNTAX ≥ 23 (n = 114)**

**n % n %**

Within 1 year of follow‐up, five deaths were reported in initial SYNTAX ≤ 22 group (**Table 7**). Four of them were due to MACE; the fifth was from cancer. Cases of cardiac death were due to (1) rupture of the myocardium on the second day after unsuccessful PCI of IRA; (2) stent thrombosis; (3) sudden cardiac arrest. We also observed seven nonfatal MI (**Table 4**). Three of them developed as a result of stent thrombosis, two as a result of destabilized non‐ culprit lesions, one as a complication of elective PCI, and one occurred 2 months after the


**Table 6.** Baseline lesions and angiographic characteristics (residual SYNTAX score groups).


**Table 7.** Outcomes after 1 year of follow‐up (initial SYNTAX score groups).

index event. Six out of ten cases of repeated target vessel revascularization were caused by the development of in‐stent restenosis (**Table 4**). Four other cases were associated with stent thrombosis. Twelve deaths were reported in patients with initial SYNTAX ≥ 23; eleven of them were caused by MACE while the twelfth was due to stroke (**Table 4**). Out of these, eleven deaths, five were the result of stent thrombosis, three were the result of an unsuccessful PCI and progressive acute heart failure, two patients died due to myocardial rupture, and the last case was associated with air embolism of the right coronary artery. Only one case of repeated target vessel revascularization out of nine was the result of in‐stent restenosis, while the other eight were performed in patients with stent thrombosis (**Table 7**).

Initial SYNTAX score ≥ 23 was significantly associated with a higher risk of death from any cause, cardiac death, recurrent MI, stent thrombosis, and combined endpoint (**Table 8**).

There was a significantly higher frequency of death from any cause, recurrent MI, and repeated nontarget vessel revascularization among patients with residual SYNTAX ≥ 9 com‐ pared to those with residual SYNTAX ≤ 8 (**Table 9**).

Residual SYNTAX ≥ 9 successfully predicted MACE such as death, recurrent MI, and repeated nontarget vessel revascularization (**Table 10**).


**Table 8.** Prognostic factors of MACE based on the initial SYNTAX score.


**Table 9.** Outcomes after 1 year of follow‐up (residual SYNTAX score groups).


**Table 10.** Prognostic factors of MACE based on the residual SYNTAX score.

#### **4.3. Discussion**

index event. Six out of ten cases of repeated target vessel revascularization were caused by the development of in‐stent restenosis (**Table 4**). Four other cases were associated with stent thrombosis. Twelve deaths were reported in patients with initial SYNTAX ≥ 23; eleven of them were caused by MACE while the twelfth was due to stroke (**Table 4**). Out of these, eleven deaths, five were the result of stent thrombosis, three were the result of an unsuccessful PCI and progressive acute heart failure, two patients died due to myocardial rupture, and the last case was associated with air embolism of the right coronary artery. Only one case of repeated target vessel revascularization out of nine was the result of in‐stent restenosis, while the other

Initial SYNTAX score ≥ 23 was significantly associated with a higher risk of death from any cause, cardiac death, recurrent MI, stent thrombosis, and combined endpoint (**Table 8**).

There was a significantly higher frequency of death from any cause, recurrent MI, and repeated nontarget vessel revascularization among patients with residual SYNTAX ≥ 9 com‐

Residual SYNTAX ≥ 9 successfully predicted MACE such as death, recurrent MI, and repeated

**n % n %**

11 4.5 9 12.2 >0.05

6 2.5 7 9.5 0.02

**Residual SYNTAX ≥ 9 (n = 74)**

**Р value**

**Major adverse cardiovascular outcomes OR (95% CI)**

Death from any cause 4.9 Cardiac death 5.6 Recurrent myocardial infarction 3.5 Stent thrombosis 5.0 Combined endpoint 2.4

eight were performed in patients with stent thrombosis (**Table 7**).

pared to those with residual SYNTAX ≤ 8 (**Table 9**).

**Table 8.** Prognostic factors of MACE based on the initial SYNTAX score.

**(n = 243)**

Death 7 2.9 10 13.5 0.001 Myocardial infarction 10 4.1 8 10.8 0.05

Stent thrombosis 5 2.1 5 6.8 >0.05

**Table 9.** Outcomes after 1 year of follow‐up (residual SYNTAX score groups).

**Variables Residual SYNTAX ≤ 8** 

Repeated target vessel revascularization

28 Interventional Cardiology

Repeated nontarget vessel revascularization

nontarget vessel revascularization (**Table 10**).

The main objective of this study was to determine the value of initial and residual SYNTAX score for prediction of adverse revascularization outcomes in patients with STEMI and MVCAD. To the best of our knowledge, there is little evidence demonstrating the prognostic value of initial and residual SYNTAX score in STEMI patients who underwent primary PCI. Meanwhile, there is a need for objective criteria including the severity of coronary lesions, which could optimize the choice of revascularization strategy for these patients [30, 31].

Here we showed that initial SYNTAX ≥ 23 points can predict the development of MACE within 1 year of follow‐up. Patients with SYNTAX ≥ 23 had significantly higher incidence of adverse outcomes such as death, MI, and stent thrombosis. However, residual SYNTAX score can be even more informative since it reflects the completeness of myocardial revasculariza‐ tion and risk of adverse events in the short‐ and long‐term follow‐up. Residual SYNTAX score ≥ 9 was significantly associated with an increased risk of death, recurrent MI, and repeated nontarget vessel revascularization. High residual SYNTAX score was more prevalent in groups with a predominance of female patients, three‐vessel coronary disease, peripheral atherosclerosis, past medical history of MI, and reduced LVEF. It is known that these clini‐ cal and demographic indicators themselves have an adverse effect on long‐term prognosis after MI [30, 31]. However, it cannot be excluded that adverse cardiovascular events are more dependent on revascularization completeness in the hospital period and, therefore, on residual SYNTAX score at the time of discharge from the hospital. It is important to note the direct association of the initial SYNTAX score ≥ 23 with residual SYNTAX score ≥ 9 points. We suggest that patients with initial severe coronary atherosclerosis are likely to retain a high residual SYNTAX at the end of hospitalization.

This highlights the need for complete revascularization in the early stages, including MS strat‐ egy (simultaneous and staged a tightly limited time interval between PCI), as well as a com‐ bination of primary PCI with subsequent coronary bypass surgery. Moreover, patients with high residual SYNTAX score may need more efficient schemes of anticoagulant and antiplate‐ let therapy with the use of modern drugs (bivalirudin, ticagrelor, prasugrel). Considering the desirability of multivessel PCI strategy targeting not only IRA but also nonculprit lesions in a limited time interval [4], we assume that the target value of residual SYNTAX score in STEMI patients to the end of in‐hospital period is ≤ 8 points. This algorithm is particularly reasoning given a sufficiently high proportion of unsuccessful PCI in patients with severe initial and residual SYNTAX (10.8%).

#### **4.4. Conclusions**

Both initial and residual SYNTAX score can predict death from all causes and/or MACE in patients with STEMI and MVCAD. Patients with high initial SYNTAX score tend to have a high residual SYNTAX score. Therefore, the patients with high initial SYNTAX score require com‐ plete revascularization and efficient antiplatelet therapy. Probably, it is required to develop a model of differentiated selection of the optimal revascularization strategy for STEMI patients to reduce the residual SYNTAX score to the end of in‐hospital period to ≤ 8 points using pri‐ mary multivessel stenting or staged PCIs. These results may be useful for risk stratification in patients with STEMI and MVCAD. In this context, in the next section of this chapter will be presented the relevant data of our own study—personalized choice of optimal strategy revas‐ cularization in STEMI patients with MVCAD.
