ACS are the most common and deleterious clinical manifestation of CAD,1,2 which continues to be the leading cause of death and morbidity in Europe, although the disease burden varies with latitude.3 ACS results in two main discharge diagnoses: unstable angina (UA) and acute myocardial infarction (AMI).

In Spain, CAD mortality rates have steadily decreased in the past 40 years (Fig. 1A). However, the absolute number of CAD deaths increased from 1980 to 2000 and steadily declined thereafter (Fig. 1B); CAD is still the first and the second most common individual cause of death in men and women, respectively.4

Figure 1.

Coronary artery disease mortality trend in Spain. A: standardized coronary artery disease mortality rates 1950-2010 by sex. B: number of annual coronary artery disease deaths 1980-2010 by sex. CAD, coronary artery disease.

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Concerning morbidity, Spanish AMI incidence rates remained relatively stable during the last 20 years of the past century, before the release of the 2000 AMI definition.5,6 CAD discharges increased from 31 032 in 1977 to 152 190 in 2004, and declined thereafter to 129 944 in 2010 (Fig. 2).7 The initial increase was probably caused in part by the new definition of AMI, by the increased elderly population with a higher ACS incidence rate than in younger age groups, and by improved survival after an acute coronary event, which increases the number of prevalent CAD patients, known to require subsequent readmissions.8–10 A new balance between the number of incident cases and CAD-survivors cohort mortality seems to have been reached after 2004, as mortality in the CAD cohort would have increased in recent years with the progressive aging of its members.

Figure 2.

Number of coronary artery disease hospital discharges in 1977-2010 by sex according to National Institute of Statistics. CAD, coronary artery disease.

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ACS care consumes a large amount of resources in Spain. At the beginning of the 21st century, direct health care costs alone were €1.03 billion annually for patients in the first year after diagnosis of ACS.11 In order to allocate human and economic resources appropriately it is essential to have data on the expected number of total and fatal cases of ACS as well as on readmissions for ACS, as it is known that the cost per patient increases with severity.12

In a previous study8 we estimated the projected number of AMI cases for 1997-2005 using the pre-2000 AMI definition, which included the use of troponine level to identify myocardial necrosis. New interest in quantifying the impact of the 2000 definition on the number of AMI cases in clinical practice and developing clinical interest in ACS prompt this update on the estimated number of ACS cases in Spain in the decades to come. The aims of this report are: a) to estimate the number of fatal and nonfatal ACS cases in 2013 and 2021, and b) to estimate the trend of ACS cases for the period 2005-2049. Our secondary aim was to analyze the number of hospitalized ACS cases by discharge diagnosis (ie, myocardial infarction and UA), which is related to prognosis, severity, and future events.

Most of the data sources for our estimations and analyses are based on descriptive studies of the ACS burden published in peer-reviewed journals in the past decade. We also used unpublished data from the REGICOR (REgistre GIroní del COR, which stands for Girona Heart Registry) study when no other source was available.13 The study projects the number of AMI and UA cases likely to occur in the population older than 24 years.

Basic Spanish data on incidence, case-fatality, 6-month mortality and readmissions for AMI and UA by sex and age groups are summarized in Table 1. AMI incidence rate was higher in men than in women in all age groups. However, population 28-day case-fatality and 6-month mortality in hospitalized AMI was higher in women than in men for both age groups. The readmission rate in the first 6 months after discharge was around 8% for all sex and age groups except women older than 74 years, in whom it reaches 11%. There were 4 times as many deaths in the over-74 population as in the younger age group. Regarding UA, there are more deaths within the first 28 days in women than in men. The 6-month readmission rate is higher in women older than 74 years (19%) than in the other groups (around 10%). From discharge to 6 months, deaths are 3 times more likely in the older age group than in the younger population.

Table 2 shows the estimated total number and estimated fatal ACS cases (AMI and UA) in the Spanish population by sex and autonomous community in 2013 and 2021. Similar estimates for hospitalized cases are also depicted by sex in Table 3. We have estimated that there will be 115 752 ACS cases in Spain in 2013 (95%CI: 114 822-116 687), 74 078 in men and 41 674 in women (Tables 2A and B); 28-day mortality is projected to be 39086 (33.8%). From the total number of ACS cases, 99 823 (86.2%) will be AMI cases and 38 633 of them (38.7%) will die within the first 28 days. From a clinical perspective, 85 326 (95%CI: 84 531-86 127) will be hospitalized (73.7%); 69 397 (81.3%) will be AMI and 15 929 UA cases. Of these patients, 8660 (10.2%) will die within 28 days of admission (Tables 3A and B; Fig. 3). Among the 76 666 ACS survivors, 8420 patients (7193 AMI and 1227 UA) will die within 6 months after discharge (11.0%).

Figure 3.

Flow-chart with the number of acute coronary syndrome cases in Spain: population data, out-of-hospital deaths and mortality at 28 days after symptom onset in hospitalized patients. ACS, acute coronary syndromes; AMI, acute myocardial infarction.

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In men, 37% of the total ACS cases and 59% of the fatal ACS cases in 2013 will occur in patients older than 75 years. In women, 66% of the total population ACS cases and 83% of the fatal ACS cases will occur in the older group (Tables 2A and B). Among hospitalized ACS cases, the older age group will represent 30% of the total ACS cases and 53% of the fatal ACS cases in men. In women, the older age group will represent 56% of the total ACS cases and 73% of the fatal ACS cases (Tables 3A and B).

With respect to ACS cases by autonomous community, in 2013 Andalusia will be the Spanish region contributing the highest number of ACS cases in both men and women (Tables 2A and B). By age group, Andalusia will contribute the most ACS cases in the population aged 25 to 74 years, while Catalonia will contribute the most cases in the over-74 population. Four communities (Andalusia, Catalonia, Valencian Community and Community of Madrid) will contribute more than 50% of total and fatal ACS cases, both at a population and hospitalized level.

Assuming that the observed 1990-2009 trends in AMI incidence and 28-day case-fatality rates for both age groups (Table 1) will continue until 2020 and both rates will be stable thereafter, we anticipate 109 772 (95%CI: 108 868-110 635) ACS cases by 2021 in Spain, with a 28-day mortality of 31.1% (34 115 deaths). Of the 83 418 (76.0%) patients who will reach the hospital, both 28-day and 6-month mortality will be just 9.3% (7761 and 7062 deaths, respectively) (Table 3).

Moreover, we estimate an important increase in the number of ACS cases in Spain over the next 35 to 40 years (Fig. 4) as the population aged 75 years or older reaches 24% of the total Spanish population by 2049. From 2013 to 2049 ACS cases will increase 69% to 116% in the older age group, rising from 28 296 to 47 920 in men and from 27 651 to 59 990 in women. On the other hand, the cases contributed by those aged 25 to 74 years will increase by 6% in men and by 26% in women if our assumptions about population trends and projections are correct.

Figure 4.

Number of acute coronary syndrome cases, trend from 2005 to 2049 by sex and age group in the Spanish population. ACS, acute coronary syndromes.

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Analysis of clinical diagnosis records indicates that 38.2% of all 2013 ACS cases will be categorized as ST elevation at admission, 55.8% as non-ST elevation and 6.0% as nonclassifiable (Table 4). We estimate that non-ST segment elevation ACS will be the most common diagnosis at admission, accounting for 53.5% and 60.1% of the cases in men and women, respectively. It also will be the most common diagnosis in all age groups analyzed. At discharge, we expect 81.3% of all 2013 ACS cases to be diagnosed as AMI and 18.7% as UA. In the MASCARA study, 9% of the initially suspected ACS cases received other diagnoses at discharge, such as stable angina or chest pain of nonischemic heart disease origin. This would increase the burden of hospital care by some 8439 ACS-suspected patients in 2013. The percentage of ACS cases discharged as AMI will be similar in men (82.2%) and women (79.7%) and in both age groups: 25 to 74 years (80.1%) and 75 years or older (83.3%).

The ratio for 2010 between our estimate and the official number of hospitalized AMI cases in Spain was 1.27, and between our estimate and the official number of CAD fatal cases was 1.12. Table 5 shows these ratios by autonomous community.

We estimate that the number of population and hospitalized ACS cases in Spain in 2013 will be 115 752 and 85 326, respectively. In a previously published estimate8 these figures were 102 023 and 74 518, respectively, and AMI diagnoses constituted 67% and 55% of these cases, respectively. In the current estimation the AMI figures have increased to 87% of population cases and 82% of hospitalized ACS patients. This change is mostly related to the increasing use and sensitivity of troponins since 2000, when the ACS definition was revised. Most of the 74 078 ACS cases in Spanish men will occur in the population aged 25 to 74 years, while in women the majority of the 41 674 cases will occur in those aged 75 years or more.

In 2013, 28-day ACS mortality will be 34% overall, 10% in patients arriving alive at the hospital and 26% in out-of-hospital deaths. These figures are slightly improved, particularly for hospitalized patients, over the 2002 estimates of 38%, 15%, and 27%, respectively.8

When considering only AMI, the population and hospitalized patients case-fatality decline is in large part related to the revision of the AMI definition in 2000.20–24 However, a significant reduction of approximately 30% to 40% in crude AMI in-hospital case-fatality has also been described in a similar time period in Spain as a whole, Ireland, United States, and Canada.19,25–27 Moreover, a longer period of observation shows that since 1995 there has been a 30% to 50% decrease in AMI population case-fatality and 50% to 60% decrease in AMI in-hospital case fatality.8 All these data concur with the estimated 33% reduction in hospitalized ACS 28-day case fatality.

We did not observe a significant reduction in out-of-hospital case-fatality between our earlier and current calculations. It has been suggested that a decrease in out-of-hospital mortality may be related to primary prevention, while in-hospital mortality may decrease as a result of improved medical care, such as extended use of effective drugs or percutaneous coronary intervention.19,28 Thus, the large decrease in AMI case-fatality observed would be mostly due to advances in acute medical care, as previously reported.29 More attention and effort should be directed toward primary prevention of the disease.

According to the MASCARA study results we assumed that non-ST elevation ACS (NSTEACS) is the main admission diagnosis for ACS while the most common discharge diagnosis will be AMI.18 Data from other studies also indicate that NSTEACS is the most frequent cause of ACS hospitalization but ACS clinical and anatomical patterns differ for ST segment elevation.24,30–34 In recent years, the proportion of patients with ST segment elevation ACS (STEACS) has decreased while the proportion of NSTEACS patients has increased. Patients with NSTEACS tend to be older and have more extensive CAD.31 Thus, taking into account the predicted aging of the population we expect an increase in the percentage of NSTEACS patients in the coming decades. Our trend analysis shows that the number of ACS cases will slightly decrease to 109 772 in 2021 but will increase to 175 751 in 2049 due to the aging of the population. During the last 10 years the Spanish population aged 25 to 74 years has increased by 15% while the population aged 75 years or more has increased by 34%.15 Moreover, it is expected that from 2013 to 2049, those aged 25 to 74 years will decrease by 9% while those aged 75 years or more will increase by 110%.16,17

The increase in ACS cases will have a dramatic impact on economic cost. Much of the ACS-associated cost is due to hospital stays, especially in intensive and coronary care units, and to revascularization.12 As official guidelines recommend an early invasive strategy such as angiography plus revascularization for both STEACS and NSTEACS patients,33,34 it is clear that ACS costs will rise accordingly. In addition, the increase in NSTEACS cases will lead to more hospital stays and health care resources use, as this condition causes ischemic recurrences and other complications.34

Although AMI incidence and CAD mortality in Spain are among the lowest in the world, the estimated number of ACS cases is especially high in young men and older women. Efforts to reduce these figures should be implemented through preventive policies. Population-based policies should be designed and applied with a focus on primary prevention and addressed to the whole population, from childhood to old age.35,36 Examples of these policies are the Spanish program NAOS37 (Estrategia para la Nutrición, Actividad Física y Prevención de la Obesidad), or the smoking bans implemented in numerous countries.37 These policies should also be combined with individual interventions in high-risk patients.38,39

Our results show that ACS cases will increase in Spain in the coming decades. The most significant cause of this increase will be the expansion of the elderly population, which will account for up to 60% of all ACS cases by 2049. The main reduction of 28-day case-fatality has been achieved in hospitalized patients: ACS sudden death remains an unsolved public health problem.

This study has been funded in part by Instituto de Salud Carlos III- RETIC RD12/0042/0061; RD12/0042/0013-FEDER-ERDF (Red de Investigación Cardiovascular-Programa Heracles), FEDER-FIS (PI081327, PI1101801) and Agència de Gestió d’Ajuts Universitaris i de Recerca-Generalitat de Catalunya (2009 SGR 1195).

None declared.