Revista Española de Cardiología (English Edition) Revista Española de Cardiología (English Edition)
Rev Esp Cardiol. 2016;69:338-40 - Vol. 69 Num.03 DOI: 10.1016/j.rec.2015.11.006

Validation of a New Risk Score for Predicting Post-discharge Cardiovascular Events in Patients With Acute Coronary Syndrome

Sergio Manzano-Fernández a,b,, Pedro J. Flores-Blanco a, Miriam Gómez-Molina a, Ángel A. López-Cuenca c, María J. Sánchez-Galian a, Mariano Valdés a,b

a Servicio de Cardiología, Hospital Clínico Universitario Virgen de la Arrixaca, Instituto Murciano de Investigación en Biomedicina (IMIB), Murcia, Spain
b Departamento de Medicina Interna, Universidad de Murcia, Murcia, Spain
c Servicio de Medicina Interna, Hospital de la Vega Lorenzo Guirao, Cieza, Murcia, Spain

Article

To the Editor,

In recent years, several studies have shown a high incidence of adverse clinical events following acute coronary syndrome (ACS).1, 2, 3, 4 Abu-Assi et al1 suggested using a new risk scoring system to predict post-discharge cardiovascular events in patients with ACS. However, as the authors acknowledge, one of the main limitations of their excellent work was the lack of an external validation process. Therefore, to improve the validity of this new scoring system, we assessed its predictive power and discriminatory power in a contemporary cohort of patients with ACS.

We carried out a retrospective study in accordance with the principles of the Declaration of Helsinki. The study was based on the data from a prospective registry of all patients with ACS admitted to a tertiary hospital in Spain. The inclusion period was from January 2012 to September 2014 (n = 1039). The study excluded patients who died in hospital (n = 55), those lost to follow-up (n = 7), and those who had incomplete data to calculate the score (n = 95; 98% due to unknown coronary anatomy). Thus, the final cohort comprised 882 patients. Follow-up at 1 year was carried out by a team of cardiologists and nursing staff, via telephone calls and review of clinical notes. Study events (cardiovascular death, acute myocardial infarction, and stroke) were defined according to the definitions used in the original study by Abu-Assi et al.1 Causes of death were determined from information obtained from telephone calls to patients’ relatives, review of clinical notes, and death certificates. In cases of uncertainty, or if the hospital notes were ambiguous or unavailable, we consulted the death register. Discriminatory power was analyzed by calculating the value of the area under the ROC curve. Calibration of the model was evaluated using the Hosmer-Lemeshow goodness of fit test. Calibration and discriminatory power were calculated for the total population and by subgroup according to type of ACS.

During the first year post-discharge, of 882 patients, 77 (8.7%) had a combined study event: 48 (5.4%) died of cardiovascular causes, 44 (5.0%) had a re-infarct, and 10 (1.1%) had a stroke. Table 1 compares patients with and without adverse clinical events: patients with adverse clinical events were older, had a higher rate of comorbidities (hypertension, diabetes mellitus, peripheral vascular disease, cerebrovascular disease, previous heart failure, and cancer) and had worse Killip class and renal function. They also had lower left ventricular ejection fraction and hemoglobin, and greater extent of coronary disease.

Table 1. Baseline Population Characteristics According to Adverse Events at 1 Year

  Combined events
  No (n = 805) Yes (n = 77) P
Demographic data
Age, y 65 ± 12 71 ± 12 <.001
Sex (women) 180 (22) 21 (27) .326
Medical history
Active smoker 284 (35) 15 (20) .005
Hypertension 566 (70) 64 (83) .017
Diabetes mellitus 354 (44) 46 (60) .008
Dyslipidemia 599 (74) 60 (78) .498
Peripheral vascular disease 50 (6) 15 (20) < .001
Ischemic stroke 77 (7) 15 (20) < .001
Ischemic heart disease a 224 (28) 25 (33) .387
Heart failure 26 (3) 6 (8) .041
Atrial fibrillation/flutter 96 (12) 14 (18) .112
COPD 62 (8) 10 (13) .106
Cancer 38 (5) 9 (12) .016
In-hospital data
Type of ACS
NSTEACS 480 (60) 44 (57) .397
STEACS 282 (35) 26 (34)  
Indeterminate ACS 43 (5) 7 (9)  
Killip > 1 on admission 134 (17) 25 (33) < .001
Initial heart rate 77 ± 20 83 ± 21 .012
Initial systolic blood pressure 136 ± 27 139 ± 27 .336
Creatinine, mg/dL 1.06 ± 0.47 1.23 ± 0.88 .007
CKD-EPI, mL/min/1.73 m2 63 ± 21 56 ± 23 .009
Hemoglobin, mg/dL 14.1 ± 1.9 13.3 ± 1.9 < .001
LVEF, % 55 ± 12 50 ± 13 < .001
LVEF < 50% 200 (25) 35 (46) < .001
Coronary angiography 797 (99) 75 (97) .215
Multivessel disease 385 (48) 48 (62) .015
Reperfusion strategy
PCI 626 (77.8) 56 (72.7) .560
Surgery 50 (6.2) 4 (5.2)  
Mixed 1 (0.1) 0 (0)  
Isolated thrombolysis 3 (0.4) 1 (1.3)  
None 125 (15.5) 16 (20.8)  
Treatment on discharge
ASA 788 (98) 71 (93) .019
Clopidogrel 570 (71) 59 (78) .225
Prasugrel 127 (16) 6 (8) .065
Ticagrelor 66 (8) 3 (4) .185
Beta-blockers 737 (92) 69 (91) .737
Statins 789 (99) 75 (99) .900
ACEI/ARB 715 (89) 70 (92) .424
Aldosterone antagonists 133 (17) 21 (28) .016

ACEI, angiotensin-converting enzyme inhibitors; ACS, acute coronary syndrome; ARB, angiotensin receptor blockers; ASA, acetylsalicylic acid; CKD-EPI, Chronic Kidney Disease Epidemiology Collaboration; COPD, chronic obstructive pulmonary disease; LVEF, left ventricular ejection fraction; NSTEACS, non-ST-segment elevation acute coronary syndrome; PCI, percutaneous coronary intervention; STEACS, ST-segment elevation acute coronary syndrome.

a Past history of acute myocardial infarction or coronary revascularization, either percutaneous or surgical.

On the new scoring system, individuals with adverse events had a higher score than those without events: 8.01 ± 4.18 points versus 5.64 ± 4.51 points. Furthermore, analysis by category showed that as the risk score increased, the percentage of events also increased progressively (< 3 points, 3.3%; 3-7 points, 7.3%; and > 7 points, 13.5%; P < .001). The calibration of this scoring system was good, but the discriminatory analyses showed an acceptable (not excellent) predictive power for cardiovascular events during the first year post-discharge (C-statistics < 0.7) (Table 2).

Table 2. Discrimination and Calibration of Scoring in the Total Population and in the Different Subgroups

Population C-statistic (95%CI) Hosmer-Lemeshow, P
Total population (n = 882) 0.66 (0.63 to 0.69) .279
NSTEACS (n = 524) 0.67 (0.63 to 0.71) .135
STEACS (n = 308) 0.66 (0.61 to 0.72) .784

95%CI, 95% confidence interval; NSTEACS, non-ST segment elevation acute coronary syndrome; STEACS, ST-segment elevation acute coronary syndrome.

In this study, we validated for the first time a recently proposed new scoring system for prediction of cardiovascular events during the first year post-discharge from hospital in patients with ACS. In our study, this new scoring system had an acceptable discriminatory power and calibration, in both the total population and in the 2 subgroups analyzed, which indicates its potential clinical usefulness as a stratification tool for patients with ACS in our environment.

Corresponding author: sergiosmf13@hotmail.com

Bibliography

1. Abu-Assi E, López-López A, González-Salvado V, Redondo-Diéguez A, Peña-Gil C, Bouzas-Cruz N, et al. El riesgo de eventos cardiovasculares tras un evento coronario agudo persiste elevado a pesar de la revascularización, especialmente durante el primer año. Rev Esp Cardiol. 2016;69:11-8.
2. Rapsomaniki E, Stogiannis D, Emmas C, Chung S, Pasea L, Denaxas S, et al. Health outcomes in patients with stable coronary artery disease following myocardial infarction;construction of a PEGASUS-TIMI-54 like population in UK linked electronic health records. Eur Heart J. 2014;35(Suppl 1):173-512.
3. Jernberg T, Hasvold P, Henriksson M, Hjelm H, Thuresson M, Janzon M. Cardiovascular risk in post-myocardial infarction patients: nationwide real world data demonstrate the importance of a long-term perspective. Eur Heart J. 2015;36:1163-70.
4. Barrabés JA, Bardají A, Jiménez-Candil J, del Nogal Sáez F, Bodí V, Basterra N, et al. Prognosis and management of acute coronary syndrome in Spain in 2012: the DIOCLES study. Rev Esp Cardiol. 2015;68:98-106.

1885-5857/© 2016 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved

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