Summary
Background
Compliance with guidelines for the management of ST-segment elevation myocardial infarction (STEMI) may be difficult in hard-to-access areas.
Aims
To analyse the characteristics, management and outcome of STEMIs occurring at altitude in the French Alps and managed by mobile medical emergency units.
Methods
From January 2006 to December 2008, from the prospective RESURCOR registry, 114 patients with a STEMI of less than 12 hours’ duration, occurring in a ski resort or at high altitude and managed by the RESURCOR care system, were identified. Baseline characteristics, treatments and in-hospital outcomes were analysed.
Results
Ninety-three per cent of patients were men; the mean age was 57 years. STEMIs occurred during or less than 1 hour after physical activity in 76.3% of cases (mainly during or after alpine/cross-country skiing). Killip class greater or equal to 2 and cardiac arrest were observed in 35% and 7.9% of cases, respectively. Fifty-two (45.6%) patients underwent thrombolysis and 62 (54.4%) had percutaneous coronary intervention (PCI). Median delays were: first call to treatment, 82 min (17–230 min); symptoms to treatment, 165 min (52–770 min). All delays were significantly longer for PCI than for thrombolysis. First call to treatment delay was less than 120 min in 98.1% of patients who underwent thrombolysis and in 51.6% who had PCI ( P < 0.0001). In-hospital survival was 96.5%.
Conclusion
Altitude STEMIs happen mainly during sporting activities. Clinical presentation is often severe, but an emergency coronary care network allows rapid reperfusion. These findings emphasize the need for an efficient network for STEMI management in geographically difficult-to-access areas.
Résumé
Contexte
Les recommandations de prise en charge de l’infarctus avec sus-décalage de ST (STEMI) peuvent être difficiles à appliquer dans les zones isolées.
Objectifs
Analyser les caractéristiques et la gestion des STEMI pris en charge par les SAMU dans les Alpes françaises.
Méthodes
Sur trois ans (2006–2008), à partir du registre prospectif RESURCOR, 114 patients avec STEMI moins de 12 heures survenant dans une station de ski ou en altitude ont été identifiés. Les caractéristiques, traitements mis en œuvre et pronostic de ces patients ont été analysés.
Résultats
Quatre-vingt-treize pour cent des patients étaient des hommes, d’âge moyen 57 ans ; 76,3 % des STEMI sont survenus au cours ou dans l’heure suivant un exercice physique intense, essentiellement du ski. Une insuffisance cardiaque Killip supérieure ou égale à 2 et un arrêt cardiaque sont survenus dans 35,0 % et 7,9 % des cas, respectivement. Cinquante-deux patients (45,6 %) on bénéficié d’une thrombolyse et 62 (54,4 %) d’une angioplastie première (AP). Les délais médian étaient : premier appel-traitement : 82 minutes [17–230] et symptômes-traitement : 165 minutes [52–770]. Ces délais étaient plus longs pour les d’AP que les thrombolyses. Le délai premier appel-traitement était moins de 120 minutes dans 98,1 % des thrombolyses et 51,6 % des AP ( p < 0,0001). La survie hospitalière était de 96,5 %.
Conclusion
Les infarctus d’altitude surviennent majoritairement au cours d’une activité sportive. La présentation clinique initiale est souvent sévère, mais un réseau de soins adapté permet une reperfusion rapide. Ces résultats soulignent la nécessité d’un réseau efficace de prise en charge des STEMI dans les zones d’accessibilité difficile.
Background
Reperfusion strategies, and the prehospital and in-hospital management of ST-segment elevation myocardial infarction (STEMI), are well codified by the guidelines of the European Society of Cardiology, especially with regard to the respective use of thrombolysis and percutaneous coronary intervention (PCI) . These recommendations state that PCI is the preferred reperfusion therapy in patients presenting within 12 hours after onset of symptoms, when performed by experienced teams within 2 hours after first medical contact (or within 90 minutes for an early presenter with a large infarct and low bleeding risk) . Conversely, fibrinolytic therapy should be performed–in the absence of contraindications–if PCI cannot be performed within the recommended time. These standards of care often need to be adapted locally, however, because of geographical specificities, especially the availability of centres that are able to perform 24-hour PCI.
The French Alps–also called “the Alpine Arch”–comprise three French departments (Isère, Savoie and Haute-Savoie) covering an area of 14,800 km 2 that is mainly mountainous and has 2.3 million inhabitants. The departments include more than 100 ski resorts, with a huge population increase during the ski season and access difficulties due to geographical and meteorological conditions. Furthermore, STEMIs that occur during sport activities in these resorts often happen in perilous, hard-to-access areas.
The REseau des URgences CORonariennes (RESURCOR, i.e. emergency coronary care network) is a network that combines the 13 services mobile d’urgence et réanimation (SMURs, i.e. mobile medical emergency units), the seven Intensive Coronary Care Units (ICCUs) and the four interventional cardiology laboratories of the Alpine Arch, and aims to optimize prehospital and in-hospital management of acute coronary syndrome in the region . A uniform management algorithm is applied across the entire network to provide every patient with the optimal time to reperfusion, according to evidence-based medicine and adapted from the updated guidelines from the European Society of Cardiology ( Fig. 1 ).
Accordingly, the aims of our study were: to describe the baseline characteristics and clinical presentation of STEMIs occurring at high altitude in the French Alps; to investigate the prehospital management and reperfusion strategies in this setting, with a particular focus on time delays; and to analyse in-hospital outcome.
Methods
Study population
From January 2006 to December 2008, 1856 patients presenting with an acute STEMI managed by a SMUR were included prospectively in the RESURCOR registry; after exclusion of 1657 patients with a STEMI that occurred at an altitude less than 1000 m, 71 patients in whom the diagnosis of STEMI was not confirmed and 14 patients who presented 12 hours after the onset of symptoms, 114 patients were identified as presenting with a STEMI of less than 12 hours’ duration that occurred at altitude; this group formed our study population.
STEMI was defined classically by the presence of compatible symptoms, associated with electrocardiogram (ECG) changes on at least two contiguous leads, with persistent ST-segment elevation or left bundle-branch block and/or significant elevation of serum markers of myocardial necrosis (creatine kinase-MB or troponin) .
Data collection
Data available from the prospective RESURCOR registry were: age, sex, clinical presentation, Killip class, initial ECG data, site of medical team intervention, hour of onset of symptoms, hour of first medical call, hour of arrival of mobile medical emergency unit, hour of treatment (thrombolysis or PCI), prehospital treatment administered, initial thrombolysis in myocardial infarction (TIMI) flow, final TIMI flow and time to TIMI 3 flow in patients with immediate coronary angiography. Prehospital outcomes were obtained from the SMUR computerized database, and in-hospital outcomes from computerized medical files from the ICCU, the interventional cardiology laboratories, and the echography and biology laboratories (i.e. coronary angiography results, PCI data, left ventricular ejection fraction, associated treatments, serum markers and clinical events).
Data analysis
Continuous variables are presented as means ± standard deviations or median values and interquartile ranges. Categorical variables are presented as absolute and relative frequency distributions. Comparisons between groups were performed using Student’s t test (or a Mann-Whitney non-parametric test in cases of non-normal distribution) for continuous variables, and a Chi-squared test or Fisher’s exact test for discrete variables. For all tests, P < 0.05 was considered as statistically significant.
Results
Baseline characteristics and clinical presentation
Of the 114 patients included, 93.0% were men and the mean age was 57 years. Most patients had two or more cardiovascular risk factors, 10.5% had diabetes, and 14.0% had previously documented coronary artery disease. Seventy (61.4%) patients were tourists, while 44 (38.5%) were local residents. There were no significant differences between patients treated by thrombolytic therapy and those who underwent PCI. Detailed baseline characteristics of the study population are summarized in Table 1 .
| All patients ( n = 114) | Thrombolysis group ( n = 52) | Primary PCI group ( n = 62) | |
|---|---|---|---|
| Men | 106 (93.0) | 49 (94.2) | 57 (91.9) |
| Mean age (years) | 57 ± 11 | 56 ± 11 | 58 ± 12 |
| Cardiovascular risk factors | |||
| Family history of CAD | 30 (26.3) | 15 (28.8) | 15 (24.2) |
| Hypertension | 34 (29.8) | 17 (32.7) | 17 (27.4) |
| Active smoking | 41 (36.0) | 20 (38.5) | 21 (33.9) |
| Diabetes mellitus | 12 (10.5) | 5 (9.6) | 7 (11.3) |
| Hypercholesterolaemia | 46 (40.4) | 24 (46.2) | 22 (35.5) |
| Obesity | 13 (11.4) | 9 (17.3) | 4 (6.5) a |
| Average BMI (kg/m 2 ) | 26.5 ± 4.3 | 27.6 ± 4.7 | 25.7 ± 4.4 |
| Number of risk factors | |||
| 0 | 10 (8.8) | 3 (5.8) | 7 (11.3) |
| 1 | 33 (28.9) | 11 (21.2) | 22 (35.5) |
| ≥ 2 | 71 (62.3) | 38 (73.0) | 33 (53.2) b |
| Metabolic status at inclusion | |||
| Glycosylated haemoglobin (%) | 5.8 ± 1.1 | 6.0 ± 1.2 | 5.7 ± 1.1 |
| Total cholesterol (g/L) | 1.87 ± 0.44 | 1.92 ± 0.46 | 1.83 ± 0.44 |
| LDL cholesterol (g/L) | 1.11 ± 0.38 | 1.12 ± 0.41 | 1.1 ± 0.39 |
| HDL cholesterol (g/L) | 0.52 ± 0.16 | 0.52 ± 0.18 | 0.52 ± 0.17 |
| Triglycerides (g/L) | 1.23 ± 0.98 | 1.19 ± 0.97 | 1.26 ± 1.0 |
| Known coronary disease | 16 (14.0) | 8 (15.4) | 8 (12.9) |
| Previous myocardial infarction | 11 (9.6) | 6 (11.5) | 5 (8.1) |
| Previous PCI | 9 (7.9) | 4 (7.7) | 5 (8.1) |
| Previous CABG | 4 (3.5) | 2 (3.8) | 2 (3.2) |
| Peripheral or carotid artery disease | 5 (4.4) | 2 (3.8) | 3 (4.8) |
Most STEMIs occurred in the winter trimester ( Fig. 2 ), during or within 1 hour of heavy physical activity in 76.3% of the patients, mainly during or after alpine or cross-country skiing ( Table 2 ). STEMIs were revealed by a typical chest pain in 84.2% of patients, while 7.9% of patients experienced a cardiac arrest as the first manifestation.
| All patients ( n = 114) | Thrombolysis group ( n = 52) | Primary PCI group ( n = 62) | |
|---|---|---|---|
| Physical activity within 1 hour of MI | 87 (76.3) | 44 (84.6) | 43 (69.4) a |
| Alpine skiing | 48 (42.1) | 25 (48.1) | 23 (37.1) |
| Cross-country skiing | 9 (7.9) | 2 (3.8) | 7 (11.3) |
| Snowshoe trial | 6 (5.3) | 4 (7.7) | 2 (3.2) |
| Biking | 8 (7.0) | 4 (7.7) | 4 (6.5) |
| Walking trial | 16 (14.0) | 9 (17.3) | 7 (11.3) |
| Clinical presentation | |||
| Typical chest pain | 96 (84.2) | 44 (84.6) | 52 (83.9) |
| Atypical chest pain | 4 (3.5) | 1 (1.9) | 3 (4.8) |
| Pulmonary oedema | 2 (1.8) | 1 (1.9) | 1 (1.6) |
| Syncope | 3 (2.6) | 1 (1.9) | 2 (3.2) |
| Cardiac arrest | 9 (7.9) | 5 (9.6) | 4 (6.5) |
| Angina within 48 hours of MI | 47 (41.2) | 18 (34.6) | 29 (46.8) |
| Anterior wall MI | 43 (37.7) | 18 (34.6) | 25 (40.3) |
| Large MI (≥ 5 ECG leads) | 47 (41.2) | 24 (46.2) | 23 (37.1) |
| Heart rate (bpm) | 77 ± 22 | 75 ± 23 | 78 ± 23 |
| Systolic blood pressure (mmHg) | 128 ± 29 | 127 ± 29 | 130 ± 27 |
| Diastolic blood pressure (mmHg) | 72 ± 19 | 70 ± 21 | 73 ± 20 |
| Site of medical intervention | |||
| Ski area | 46 (40.3) | 22 (42.3) | 24 (38.7) |
| Physician’s office | 41 (36.0) | 19 (36.5) | 22 (35.5) |
| Home/hotel | 27 (23.7) | 11 (21.2) | 16 (25.8) |
| Initial SMUR intervention | 45 (39.5) | 25 (48.1) | 20 (32.3) b |
| Helicopter transfer | 92 (80.7) | 45 (86.5) | 47 (75.8) |
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