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  • „ ORIGINAL ARTICLE

Acute myocardial infarction in young patients

Wojciech Zasada1, 2, Beata Bobrowska2, Krzysztof Plens1, Artur Dziewierz1, 3, Zbigniew Siudak4, Andrzej Surdacki3, Dariusz Dudek2, 3, Stanisław Bartuś2, 3

1KCRI, Kraków, Poland

2Department of Cardiology, University Hospital, Kraków, Poland

3Institute of Cardiology, Jagiellonian University Medical College, Kraków, Poland

4Collegium Medicum, Jan Kochanowski University, Kielce, Poland

Correspondence to:

Wojciech Zasada, MD, PhD,

KCRI,

Miechowska 5B, 30–055 Kraków, Poland,

phone: + 48 12 623 19 30,

e-mail: zasada.wojciech@gmail.com

Copyright by the Author(s), 2021

Kardiol Pol. 2021; 79 (10): 1093–1098; DOI: 10.33963/KP.a2021.0099

Received: March 24, 2021

Revision accepted: August 31, 2021

Published online: August 31, 2021

Abstract

Background: Acute myocardial infarction (AMI) is an incredibly destructive disease when it occurs in a young patient. Thus, the investigation of the disease presentation and treatment options seem to be particularly important in young patients with AMI.

Aims: The study objective was to investigate the differences between young and older patients diagnosed with AMI in terms of clinical characteristics and treatment strategies.

Methods: The patient data comes from the National Registry of Procedures of Invasive Cardiology (ORPKI). Between 2014 and 2017, data of more than 230 000 patients with a diagnosis of AMI were collected in that registry. Young patients were defined as under 40 years old.

Results: Young patients with AMI (n = 3208, 1.3%) compared with older patients with AMI were more often men (86.3% vs. 65.8%; P <0.001) with higher body weight (mean 85.9 vs. 79.7 kg; P <0.001). Typical risk factors of coronary heart disease were less frequent in younger patients than in older patients. However, in the under-40 group, there was a significantly higher number of current smokers (37.5% vs. 23.0%; P<0.001). Young patients with AMI were more often diagnosed with ST-segment elevation myocardial infarction (STEMI; 62.0% vs. 50.0%; P <0.001). Moreover, they had more frequently non-significant stenosis in coronary arteries diagnosed (14.4% vs. 6.8%; P <0.001). The left anterior descending artery was more frequently an infarct-related artery in young patients (51.3% vs. 36.3%; P <0.001). Bioresorbable vascular scaffolds were more commonly implanted in young patients with AMI than in the older ones (5.6% vs. 0.9%; P <0.001). The relative number of AMI in the young patients increased from 1.20% in 2014 to 1.43% in 2017.

Conclusions: Smoking is the most common risk factor in young adults. The relative number of AMI in young patients is growing.

Key words: acute myocardial infarction, angiography, coronary artery disease, percutaneous coronary intervention

Kardiol Pol 2021; 79, 10: 10931098

What’s new?

Acute myocardial infarction (AMI) in young patients is often a slightly different disease than in older patients. The prevention of acute myocardial infarction in a young patient should primarily focus on smoking cessation. The left anterior descending artery is the most common infarct-related artery in young patients. The additional diagnostic tools should be considered during angiography to diagnose the reasons for AMI other than atherosclerosis. The relative number of AMI in young patients is growing.

INTRODUCTION

Acute myocardial infarction (AMI) is one of the leading causes of mortality in the Polish population. Thus, many efforts are directed towards the primary prevention of coronary artery disease, and fast diagnostic methods are used. A network of invasive cardiology centers is developed to provide the optimal diagnostic and treatment options for the whole population.

In recent years, the relative incidence of ST-segment elevation myocardial infarction (STEMI) has been decreasing while the relative incidence of non-ST-segment elevation myocardial infarction (NSTEMI) has been expanding [1]. AMI is an incredibly destructive disease, especially when it occurs in a young patient. It is associated with significant morbidity, psychological consequences, and financial restraints for the patient and the family. Thus, the investigation of the AMI causes, presentation, and management options seems to be particularly important in young patients.

METHODS

The data analyzed in this publication come from the National Registry of Procedures of Invasive Cardiology (ORPKI). ORPKI is a Polish national registry that collects data on percutaneous procedures in invasive cardiology performed in 163 cardiac catheterization laboratories and invasive cardiology departments. From January 1, 2014, the Jagiellonian University Collegium Medicum in Kraków is the entity responsible for maintaining the database. The design and details of the ORPKI registry have been previously described [2, 3]. Because of the data nature (registry of procedures), the ethics committee approval or patients’ written informed consent was not required.

The study investigated differences in patient characteristics and the disease presentation and treatment between young and older patients. The young patients were defined as under 40 years old.

Statistical analysis

Categorical variables were presented as numbers and percentages. Continuous variables were expressed as mean, standard deviation (SD), median, and interquartile range (IQR). The Mann-Whitney U test was used to compare differences between groups, although the age and weight of subjects were compared using h’s t-test. The normality was assessed by the Kolmogorov-Smirnov-Lilliefors test (or by the Shapiro-Wilk test for less than 2000 observations). Ordinal variables were compared by Cochran-Armitage test for trend or Mann-Whitney U test. Categorical variables were compared by Pearson’s chi-squared test or Fisher’s exact test if 20% of cells had an expected count of less than 5.

The linear regression model was created to investigate a trend in quarter data of the percentage of young patients’ procedures. The Shapiro-Wilk test checked the normality of model residuals. To check heteroscedasticity, the Brown-Forsythe test was used to examine whether the upper half’s residuals had different variability than those in the lower half (median split). The Durbin-Watson test checked the autocorrelation of residuals.

Two-sided P-values <0.05 were considered statistically significant. All calculations were performed with JMP®, Version 14.2.0 (SAS Institute Inc., Cary, NC, USA).

RESULTS

The data of 237 747 patients with a diagnosis of myocardial infarction were collected in the ORPKI Registry between 2014 and 2017. In that group, 3 208 (1.3%) patients were under 40 years old (mean [SD] age, 34.5 [4.6] vs. 67.3 [11.3] years).

Young patients with myocardial infarction were more frequently men with significantly higher body weight than their older counterparts (Table 1).

Table 1. Demographic data — summary

Variable

Measure/level

Age <40

Age ≥40

Total

Test

P-value

Year

N

3208

234539

237747

CA

<0.001

2014

882 (27.49%)

72612 (30.96%)

73494 (30.91%)

2015

827 (25.78%)

61347 (26.16%)

62174 (26.15%)

2016

782 (24.38%)

51185 (21.82%)

51967 (21.86%)

2017

717 (22.35%)

49395 (21.06%)

50112 (21.08%)

Age, years

N

3208

234539

237747

W

<0.001

Mean (SD)

34.53 (4.57)

67.25 (11.29)

66.81 (11.85)

Gender

N

3166

232788

235954

P

<0.001

Female

435 (13.74%)

79699 (34.24%)

80134 (33.96%)

Male

2731 (86.26%)

153089 (65.76%)

155820 (66.04%)

Weight, kg

N

3208

234539

237747

W

<0.001

Mean (SD)

85.94 (18.89)

79.73 (17.37)

79.81 (17.40)

Abbreviations: CA, Cochran–Armitage test; P, Pearson’s chi-squared test; W, Welch’s t-test

Typical risk factors of coronary heart disease in young patients were slightly different from those in the older population, namely diabetes mellitus, arterial hypertension, and chronic kidney disease were less frequent in younger patients than in older patients. However, in the under-40 group, there was a significantly higher number of current smokers. Detailed data regarding the medical history of both groups of patients are presented in Table 2.

Table 2. Myocardial infarction (MI) risk factors

Variable

Measure/level

Age <40

Age ≥40

Total

Test

P-value

Diabetes

N

3208

234539

237747

P

<0.001

Yes

171 (5.33%)

53106 (22.64%)

53277 (22.41%)

No

3037 (94.67%)

181433 (77.36%)

184470 (77.59%)

Previous stroke

N

3208

234539

237747

P

<0.001

Yes

19 (0.59%)

8845 (3.77%)

8864 (3.73%)

No

3189 (99.41%)

225694 (96.23%)

228883 (96.27%)

Previous MI

N

3208

234539

237747

P

<0.001

Yes

230 (7.17%)

53269 (22.71%)

53499 (22.50%)

No

2978 (92.83%)

181270 (77.29%)

184248 (77.50%)

Previous PCI

N

3208

234539

237747

P

<0.001

Yes

225 (7.01%)

52974 (22.59%)

53199 (22.38%)

No

2983 (92.99%)

181565 (77.41%)

184548 (77.62%)

Previous CABG

N

3208

234539

237747

P

<0.001

Yes

15 (0.47%)

10418 (4.44%)

10433 (4.39%)

No

3193 (99.53%)

224121 (95.56%)

227314 (95.61%)

Smoking status

N

3208

234539

237747

P

<0.001

Yes

1203 (37.50%)

53878 (22.97%)

55081 (23.17%)

No

2005 (62.50%)

180661 (77.03%)

182666 (76.83%)

Psoriasis

N

3208

234539

237747

P

0.39

Yes

17 (0.53%)

1009 (0.43%)

1026 (0.43%)

No

3191 (99.47%)

233530 (99.57%)

236721 (99.57%)

Hypertension

N

3208

234539

237747

P

<0.001

Yes

961 (29.96%)

156084 (66.55%)

157045 (66.06%)

No

2247 (70.04%)

78455 (33.45%)

80702 (33.94%)

Kidney disease

N

3208

234539

237747

P

<0.001

Yes

48 (1.50%)

13894 (5.92%)

13942 (5.86%)

No

3160 (98.50%)

220645 (94.08%)

223805 (94.14%)

COPD

N

2374

166443

168817

P

<0.001

Yes

2 (0.08%)

4654 (2.80%)

4656 (2.76%)

No

2372 (99.92%)

161789 (97.20%)

164161 (97.24%)

Abbreviations: CABG, coronary artery bypass grafting; COPD, chronic obstructive pulmonary disease; PCI, percutaneous coronary intervention; other — see Table 1

Based on patient characteristics on admission to the hospital (Table 3), young patients with AMI had significantly more often diagnosed STEMI with cardiac arrest during the index hospitalization. Even though the rate of direct transport to the primary Percutaneous Coronary Interventions (PCI) center was similar in both groups, time delays from the onset of symptoms to the treatment were lower in the younger group (Table 4).

Table 3. Patient status on admission

Variable

Measure/level

Age <40

Age ≥40

Total

Test

P-value

Killip class IV on admission

N

2468

164245

166713

P

<0.001

Yes

43 (1.74%)

4800 (2.92%)

4843 (2.90%)

No

2425 (98.26%)

159445 (97.08%)

161870 (97.10%)

Indication

N

3208

234539

237747

P

<0.001

Stemi

1988 (61.97%)

117264 (50.00%)

119252 (50.16%)

Nstemi

1220 (38.03%)

117275 (50.00%)

118495 (49.84%)

Cardiac arrest at baseline

N

3035

196878

199913

P

0.03

Yes

138 (4.55%)

7420 (3.77%)

7558 (3.78%)

No

2897 (95.45%)

189458 (96.23%)

192355 (96.22%)

Hypothermia at baseline

N

3035

196878

199913

F

0.15

Yes

8 (0.26%)

298 (0.15%)

306 (0.15%)

No

3027 (99.74%)

196580 (99.85%)

199607 (99.85%)

Direct transport

N

3035

196878

199913

P

0.39

Yes

452 (14.89%)

28230 (14.34%)

28682 (14.35%)

No

2583 (85.11%)

168648 (85.66%)

171231 (85.65%)

Abbreviations: F, Fisher’s exact test; NSTEMI, non-ST segment elevation myocardial infarction; STEMI, ST-segment elevation myocardial infarction; other — see Table 1

Radial access was used more frequently in the group of young patients. Still, additional diagnostic devices including intravascular ultrasound (IVUS), optical coherence tomography (OCT), or fractional flow reserve (FFR) were used with similar frequency in both study groups. Moreover, the young patients had more frequently non-significant stenosis in coronary arteries and a single-vessel disease when significant lesions were diagnosed (Table 5).

During the PCI procedure, aspiration thrombectomy was used in the young patients twice as often as in their older counterparts (Table 6).

Moreover, the young patients received thrombolytic therapy more often, and new antiplatelet agents were used more frequently than in the older group. In more than half of the young patients, an infarct-related artery was the left anterior descending artery (LAD, Table 7).

Table 7. Percutaneous coronary intervention (PCI) procedure — lesion localization

Variable

Measure/level

Age <40

Age ≥40

Total

Test

P-value

LMCA

N

2060

198088

200148

P

<0.001

Yes

38 (1.84%)

6396 (3.23%)

6434 (3.21%)

No

2022 (98.16%)

191692 (96.77%)

193714 (96.79%)

RCA

N

2060

198088

200148

P

<0.001

Yes

516 (25.05%)

63947 (32.28%)

64463 (32.21%)

No

1544 (74.95%)

134141 (67.72%)

135685 (67.79%)

LAD

N

2060

198088

200148

P

<0.001

Yes

1056 (51.26%)

71949 (36.32%)

73005 (36.48%)

No

1004 (48.74%)

126139 (63.68%)

127143 (63.52%)

Circumflex

N

2060

198088

200148

P

<0.001

Yes

290 (14.08%)

38253 (19.31%)

38543 (19.26%)

No

1770 (85.92%)

159835 (80.69%)

161605 (80.74%)

SvG

N

2060

198088

200148

P

<0.001

Yes

1 (0.05%)

2234 (1.13%)

2235 (1.12%)

No

2059 (99.95%)

195854 (98.87%)

197913 (98.88%)

LIMA/RIMA

N

2060

198088

200148

F

0.06

Yes

0 (0.00%)

348 (0.18%)

348 (0.17%)

No

2060 (100.00%)

197740 (99.82%)

199800 (99.83%)

Abbreviations: LAD, left anterior descending artery; LIMA, left internal mammary artery; LMCA, left main coronary artery; RCA, right coronary artery; RIMA, right internal mammary artery; SvG, saphenous vein graft; other — see Table 1–3

Drug-eluting stents (DES) were used with similar frequency in both study groups, but bare-metal stents (BMS) were implanted more often in the older patients. On the contrary, bioresorbable vascular scaffolds (BVS) were more commonly chosen for the young patients (Supplementary material, Table S1). The percentage of patients with the final complete flow (TIMI grade 3 flow) in the infarct-related artery was similar in both groups. Even though the younger patients have higher body weight than the older ones, the total amount of contrast and total radiation dose during the procedures were lower in the under-40 group (Table 8).

The frequency of periprocedural complications during coronary angiographies and PCI procedures was relatively small and similar in both study groups (Supplementary material, Table S2).

The absolute number of AMI decreased from year to year, but the relative number of AMI in the young patients increased from 1.20% in 2014 to 1.43% in 2017. This surge is statistically significant when calculated quarterly = 0.0240; 95% CI, 0.00510.0429; R² = 34.66%; P = 0.02).

DISCUSSION

According to our study, AMI in young patients seems to be a slightly different medical problem than in older patients. These differences could be observed in several distinct areas. When it comes to demographic data, a typical young patient with AMI is a smoking man. A similar observation was found in other studies [4–6]. Other specific AMI risk factors like arterial hypertension, diabetes mellitus, or chronic kidney disease are more often observed in older patients with AMI. Our results are concordant with the results of the study by Chhabra et al. [7]. As we know from previously published studies, the correlation of even one risk factor with the patient’s age may significantly affect his prognosis [12]. Apart from the abovementioned, a significant risk factor of AMI, especially in young patients, is familial hypercholesterolemia. Due to the nature of the data, it was not possible to assess this risk factor’s occurrence in our study population. Clinically, in young patients with AMI, STEMI is more prevalent [1]. It was also described that in young patients with AMI, significant coronary artery stenosis is observed more frequently in the LAD than in other arteries [8], which is concordant with our findings.

Unfortunately, because of the data characteristics (registry), it is impossible to distinguish between true atherosclerotic lesions and spontaneous coronary artery dissection (SCAD), which might be an underlying cause of AMI, especially in young women. Similarly, the domination of non-significant lesions and one-vessel disease in young patients was described previously in the Russian population [9]. Patients with non-significant lesions on coronary angiography, as well as with no evidence of atherosclerosis, but with the diagnosis of myocardial infarction (MINOCA, almost 35% of young patients in contrary to the older ones 9%), are eventual candidates for extended diagnostic workup of coronary arteries, like IVUS or OCT. Unfortunately, this management was rarely reported in our registry (approx. 0.3%). Even though our patients’ groups had similar rates of periprocedural complications, the extended follow-up results may differ. As it was published previously, early coronary artery disease is strongly associated with AMI and death within 30 days of presentation in patients hospitalized for chest pain [10].

In comparison to older patients with AMI, in patients under 40 with this medical condition, the reason for their troponin elevation is more often not so obvious. Accurate differential diagnosis may require in this case the use of more sophisticated diagnostic tools. During long-term follow-up in young patients with AMI, the risk of myocardial ischemia recurrence may be higher when the underlying cause of ischemia is not thoroughly diagnosed. Close follow-up and post-hospital cardiac control, whose positive effects have been studied and described [13], seem to be particularly justified in the group of young patients with AMI.

CONCLUSION

AMI in young patients (defined as under 40 years old) is a different disease than in their older counterparts. Younger patients with AMI have distinct risk factors profiles and angiographic findings in coronary arteries. The primary prevention of AMI in young patients should mainly focus on smoking cessation. During coronary angiography, additional diagnostic tools, such as IVUS, OCT, or microvascular examination should be considered, as reasons other than atherosclerosis are particularly frequent in this group of patients.

Limitations

Despite a relatively large group of patients, the data acquisition methodology (the ORPKI registry) does not allow the collection of data regarding familial hypercholesterolemia or hyperuricemia, which may play a role in the development of coronary artery disease [11]. We could not perform a standardized analysis of patient angiography, so it was not possible to assess the role of muscle bridge in LAD stenosis and SCAD.

Supplementary material

Supplementary material is available at https://journals.viamedica.pl/kardiologia_polska.

Article information

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