In 2015, the WHO reported 17.7 million deaths from 'cardiovascular diseases', which accounted for 31% of global mortality, and more than 75% of these deaths occurred in low- and middle-income countries ¹. In Colombia, between 2005 and 2017, diseases of the circulatory system were the leading cause of mortality. For the latter year, ischemic heart disease accounted for 53.3% (38,618) of deaths within that group of diseases, exhibiting adjusted mortality rates ranging from 78.89 to 80.07 deaths per 100,000 population ².

The increase in cardiovascular diseases is part of the epidemiological transition towards a more costly morbidity profile (predominance of chronic non-communicable diseases), population growth, and the changing demographic structure (aging), threatening the sustainability of the health system. In addition, regarding quality, the limitations to access and continuity in the provision of services, the disarticulation of the system's actors, and the inefficiency of spending create significant challenges for improving efficiency and health outcomes ³.

As a strategy to improve health care delivery and contribute to the sustainability of the system, clinical management strategies have been designed and implemented worldwide, called 'clinical pathways', also known as 'clinical pathways' or 'critical pathways', and are proposed as a process to reduce the gap between the recommendations that are theoretically documented in 'clinical practice guidelines' (CPG) and the actual application of the concepts by health care teams in their daily practice ⁴.

Clinical pathways are defined as interdisciplinary and structured plans that seek to implement recommendations based on scientific evidence into local care structures, detailing the steps in a time sequence to standardize care for a specific clinical problem, procedure, or episode of care in a population ⁵ and are used in clinical conditions of relevance, frequency and population impact such as cardiovascular diseases. These are a group of pathologies that have been sufficiently studied and have recommendations based on the best evidence to guide clinical practice in a standardized, effective, and efficient manner. Despite this, multiple studies show that these objectives are not achieved ^6,7, which is all the more important given their high frequency and mortality at the global and local levels.

Although there is abundant international literature on the benefits of clinical pathways in managing acute coronary syndrome, there are also contradictory results. Systematic reviews suggest that the evidence is insufficient to formally recommend 'clinical pathways' as a strategy that could become an integral part of public policy in different health systems ^8-11. Therefore, the objective of this study was to review the results of clinical pathways in the management of acute coronary syndrome due to the complexity of variables (biological, cultural, political, economic, etc.) that may represent variations in the international context and because it is necessary to continue adding evidence that validates or discards this clinical management strategy as a tool for quality improvement and can contribute to the sustainability of the Colombian health system.

The search for information was carried out in the databases Medline, Lilacs, SCOPUS, OVID, the journal Critical Pathway in Cardiology, and the Google Scholar search engine; the following words were determined as MESH for the search strategy: acute coronary syndrome and critical pathway and effectiveness. Other terms such as comparative, effectiveness, research, quality indicators, health care, clinical paths, clinical pathways, and myocardial infarction were also explored; however, no precise results were obtained or directly related to the topic of interest.

The search was limited to English and Spanish, no time limit was established, and as selection criteria, articles related to the evaluation of the results of the 'clinical pathway' strategy in the management of acute coronary syndrome were included, where at least one of the following domains and components were included:

- Processes of care aimed at assessing timeliness of care.

Articles with:

- Qualitative outcomes

The exploration of the information in the databases was done by two reviewers independently, selecting articles by title that were related to the research topic to be consolidated by year and source of information in an Excel file. Duplicate articles were eliminated, and then the selection criteria were applied to the abstracts, detailing the reasons for their exclusion.

The selected articles were re-evaluated for eligibility criteria and applied to the complete text, specifying the reasons for exclusion in compliance with the PRISMA ScR extension guideline for scoping reviews ¹². The articles that were included were not assessed for bias because it was considered that data could be extracted from all articles for the synthesis of qualitative analysis of the evaluation of the clinical pathway strategy for the management of acute coronary syndrome.

The indicators for the clinical pathway endpoints were classified according to the domains: processes of care, clinical outcomes, and administrative and financial outcomes, as well as their components: timeliness, mortality, complications, hospital stay, and early discharge (Table 1).

Table 1

Dominio	Components	Indicator	Reference	positive effect	No Change	Final assessment of the effect **
Care process	Opportunity	Door - ECG	Daghash, 2020	0 (1/3) *	1 (2/3) *	No change
			Daghash, 2020	1 (3/5) *	0 (2/5) *
		Door-Needle	Xin Du, 2017		1	No change
			Yangfeng Wu, 2019		1
			Daghash, 2020	1 (5/6)*	0 (1/6)*
		Ballon-Door	Aeyels, 2018	1		positive change
			Xin Du, 2017		1
Clinical Outcomes	Mortality	Intrahospital	Daghash, 2020	0 (1/3)*	1 (2/3)*	No change
			Mahler, 2018		1
			Polanczyk, 2003	1
		to 30 days	Dhaliwal, 2020	1		Undetermined
			Mahler, 2018		1
		30 days to 1 year	Daghash, 2020	0 (1/3)*	1 (2/3)*	No change
			Stopyra, 2020	1
			Jo-JoHai, 2019	1
			Xin Du, 2017		1
	Complications	MACE	Daghash, 2020	1 (3/4)*	0 (1/4)*	No change
			Than, 2018		1
			Mahler, 2015		1
			Polanczyk, 2003		1
			Xin Du, 2017		1
			Yangfeng Wu, 2019		1
			Siebens, 2010		1
			Dhaliwal, 2020		1
Administrative and financial results	Stay	Average length of stay	Daghash, 2020	1 (5/9)*	0 (4/9)*	positive change
			Mahler, 2015	1
			Siebens, 2010	1
			Than, 2018	1
Early discharge	Early discharge	Mahler, 2018		1	positive change

* For the SR of Daghash et al. ¹¹, 1 or 0 is assigned in the columns of pathway effects, depending on whether the trend is positive, no change or negative, and in parentheses the total number of studies that evaluated this indicator is listed in the denominator and those that had the effect corresponding to the column in the numerator.

For the final assessment of the effect of the pathway on the different components of the domains evaluated, the indicators of each study were considered, classifying their results as follows:

Positive effect: when the results of the evaluated variable showed a statistically significant variation towards improvement and the desired effect.

Adverse effect: when the results of the variable evaluated showed a statistically significant variation against the desired effect.

No change: When the endpoint results showed no change with the implementation of the clinical pathway, or the resulting changes were not statistically significant. Indeterminate: despite reporting statistically significant changes in the different studies, the effects between studies were contradictory. They did not allow an actual positive or negative trend on the variable to be assessed.

For the systematic review by Daghash et al. ¹¹, the total number of studies that evaluated each variable was considered. Their effect was rated (positive, negative, or no change) according to the trend in each study. In brackets, the total number of studies that evaluated that indicator was listed in the denominator and those with the corresponding effect in the numerator to finally conclude the final assessment of the effect according to the positive or negative trend (Table 1).

The final assessment of the effect of the pathway on the indicator is a quantitative concept summarizing the trend based on the number of studies that assessed the indicator. Where no trend was possible, it was assessed as undetermined.

A total of 489 articles were obtained because of the initial search, and after filtering the information, the articles were filtered by title and abstract. Fifty-six articles were selected after the elimination of duplicates. After reading and analyzing the abstracts, 14 articles were included for full-text reading, as they met the inclusion and exclusion criteria, complying with the recommendations of the PRISMA ScR extension guide for scoping reviews (Figure 1).

Figure 1

The 14 selected studies were published between 2003 and 2020, and 86% were published in the last seven years.

Among the studies included in this review, six are quasi-experimental (before-after) studies, four randomized clinical trials (RCTs), two prospective observational cohort studies, one descriptive observational study, and one systematic review (SR). These studies were conducted in seven different countries (USA, China, Belgium, New Zealand, Australia, Brazil, and Colombia), and the systematic review that is part of our study included research from six additional countries (Italy, Denmark, Turkey, Singapore, South Korea and Japan) (Table 2).

Table 2

Year	Author	Title	Design
2020	Daghash	The effect of acute coronary syndrome care pathways on in-hospital patients: A systematic review	Systematic review
2020	Stopyra	Heart pathway implementation safely reduces hospitalizations at one year in patients with acute chest pain	Cuasi-experimental
2020	Dhaliwal	Reduced admission rates and resource utilization for chest pain patients using an electronic health record-embedded clinical pathway in the emergency department	Cuasi-experimental /Retrospective
2019	Jo-Jo Hai	Guideline-based critical care pathway improves long-term clinical outcomes in patients with acute coronary syndrome	Cuasi-experimental
2019	Yangfeng Wu	Effect of a quality of care improvement initiative in patients with acute coronary syndrome in resource-constrained hospitals in China: a randomized clinical trial	Clinical trial randomized
2018	Aeyels	Care pathway effect on in-hospital care for ST-Elevation myocardial infarction	Cuasi-experimental
2018	Than	ICare-ACS (Improving Care Processes for Patients With Suspected Acute Coronary Syndrome)	Pragmatic Clinical trial
2018	Mahler	Safely identifying emergency department patients with acute chest pain for early discharge: Heart pathway accelerated diagnostic protocol	Cuasi-experimental
2017	Xin Du	Treatment and outcomes of acute coronary syndromes in women: An analysis of a multicenter quality improvement Chinese study	Clinical trial
2015	Sprockel	Quality of care in acute coronary syndromes: A critical path implementation	Observational descriptive prospective
2015	Mahler	The heart pathway randomized trial	Clinical trial
2014	Scott	"Implementation of a chest pain management service improves patient care and reduces length of stay"	Prospective cohort
2010	Siebens	Implementation of the guidelines for the management of patients with chest pain through a critical pathway approach improves length of stay and patient satisfaction but not anxiety	Cuasi-experimental
2003	Polanczyk	Improvement in clinical outcomes in acute coronary syndromes after the implementation of a critical pathway	Prospective cohort

The picture of the effectiveness of clinical pathways needs to be more consistent on some indicators. However, our review found an apparent positive effect on improving door-to-balloon time, decreasing hospital stay, and increasing early discharge. These results coincide with those reported in the systematic review by Daghash et al ¹¹.

International literature was found that refers to the implementation and evaluation of the effectiveness of clinical pathways in acute coronary syndrome, but in the national context, the experiences and evaluations that were found were very scarce, the only one selected being a retrospective descriptive observational study conducted by Sprockel et al. ²⁴, in the city of Bogotá.

We identified that clinical outcome indicators, such as mortality and complications, were the most evaluated (79%), while administrative and financial outcome indicators, such as length of stay, and process indicators, such as timeliness of care, were the next most evaluated (36%). This partially differs from the data reported in the systematic review by Daghash et al. ¹¹, and other systematic reviews ^39-41, where clinical outcome indicators were not the most frequently evaluated but agrees that timeliness and length of stay indicators are the most frequently examined in those reviews. What is constant in our study and in the different reviews analyzed is that the authors prioritize indicators that evaluate the technical dimension of the care process, leaving aside the interpersonal dimension, such as indicators that evaluate the impact on team communication or user satisfaction, which would provide another perspective on the evaluation of the effectiveness of clinical pathways for future studies.

Clinical outcome indicators vary widely between studies regarding how they are measured, making synthesis and reliability of conclusions in this domain difficult.

Some studies assessing the effects of pathways on in-hospital and 30-day mortality included assessments of all-cause mortality, while others related it specifically to acute coronary events. For the assessment of one-year mortality, in some studies, there was no consistency in the inclusion of 30 days post-hospital discharge within the one-year follow-up; furthermore, in two of these studies, follow-up was longer than one year, and mortality was not reported independently of MACE, without achieving a clear differentiation.

Complications were evaluated in eight selected studies ^{11,19,21-23,27,28,35}, but their definition was variable and unclear among the different authors. Some studies examined the presence of MACE (Major Adverse Coronary Events), including all-cause mortality; others included coronary events or recurrent ischemia without specifying their classification, while others were specific in reporting acute myocardial infarction, and one study even considered heart failure within the reported complications.

Regardless of the shortcomings in the standardization of mortality and complication measures, our review showed a clear tendency to find no significant changes in clinical outcomes with the implementation of clinical pathways, which contrasts with other literature reviews, such as the Cochrane systematic review by Rotter et al. ⁸, where, despite being an evaluation of the effectiveness of clinical pathways in different pathologies and health conditions and not specifically in ACS, one of the main findings was a significant reduction in hospital complications associated with the introduction of pathways, but this can be explained because 6 of the 7 studies supporting that conclusion in that review examined invasive conditions or interventions, e.g. surgical procedures or mechanical ventilation, where there is more likelihood of using complication measures such as infection and bleeding which are more objective outcome measures. Furthermore, on clinical pathways, it has been previously suggested that this strategy works best for 'phenomena with a predictable course' ⁴, i.e., conditions, pathologies, or procedures where the process of care or performance can be systematically organized, and outcomes have the least possible variability; this may be particularly true for clinical outcomes in ACS.

In our review, we found no adverse changes in clinical outcomes associated with the implementation of pathways but a positive impact on timeliness and length of stay indicators, which confirms the importance of this clinical management tool for optimizing resources without affecting the safety of care.

The absence of negative results associated with implementing clinical pathways in all the studies and other reviews may reflect this strategy's safety and low risk. However, it may also be due to a publication bias, where the authors prefer to report only successful or neutral results rather than the negative results of some implementation experiences.

It is essential to highlight that in the effectiveness studies and the experiences of implementation of clinical pathways that were evaluated, we found that in the international context, the pathways have a more clinical focus, with little integration of administrative processes, which leaves aside one of the implicit benefits of this strategy, where the interdisciplinary coordination of the different actors and the alignment of clinical and administrative processes can improve health care outcomes, and this may be an approach to consider in the Colombian context, where our health system has administrative constraints that directly or indirectly affect the delivery of services to patients.

Clinical pathways are clinical management strategies that have been widely used in many countries for decades. However, they need a unified international definition, and evaluating their effectiveness has multiple drawbacks due to the need for more standardization to measure their results. Even so, there is a clear tendency in this and other literature reviews to show positive effects in improving the timeliness of care, reducing the length of stay, and stimulating early discharge without detriment to the safety of care or clinical outcomes. On the other hand, there are few outcome evaluations related to the interpersonal dimension, such as indicators assessing the impact on team communication or user satisfaction, which would provide another perspective on evaluating the effectiveness of clinical pathways for future studies.