Global Cardiac Surgical Volume and Gaps: Trends, Targets, and Way Forward

Abstract

Background

More than 1 million cardiac surgical procedures are estimated to occur yearly. Little is known about country-level procedural estimates and volumes needed to provide adequate population coverage. We evaluated annual cardiac procedural volumes for high-income countries and present target volumes for countries to work toward as part of universal health coverage agendas.

Methods

Academic and gray literature was searched for total annual volumes for high-income countries for all cardiac surgery, coronary artery bypass grafting (CABG), valvular surgery, and congenital heart surgery between 2010 and 2021. Matched populations were obtained from the World Bank World Development Indicators. Volume targets by country income group were proposed on the basis of published expert opinion and adjusted for cardiovascular disease burdens.

Results

An average total cardiac surgical volume of 123.2 per 100,000 population per year was performed in high-income countries (36.7 CABG, 30.8 valvular, 7.9 congenital). Unadjusted annual volume targets per 100,000 population for low- and middle-income countries are 61.6 cardiac surgical procedures, 18.3 CABGs, 15.4 valvular surgical procedures, and 4.0 congenital heart operations. Adjusted for cardiovascular disease burdens, total cardiac surgical volume targets are 86.1 procedures per 100,000 population per year for upper-middle-income countries, 55.1 for lower-middle-income countries, and 40.2 for low-income countries.

Conclusions

Target annual procedural volumes present opportunities to strategically work toward expanding cardiac surgical capacity to meet the needs of countries’ populations. These targets may guide country-specific targets, which should be optimized through the expert opinion and lived experiences of local health care professionals and the context-specific population needs.

Visual Abstract

In Short.

• ▪High-income countries perform an average total cardiac surgical volume of 123.2 per 100,000 population per year.
• ▪Adjusted for cardiovascular disease burdens, estimated total cardiac surgical volume targets are 86.1 procedures per 100,000 population per year for upper-middle-income countries, 55.1 for lower-middle-income countries, and 40.2 for low-income countries.

Cardiovascular disease (CVD) is the leading cause of death worldwide, with nearly 18 million deaths each year.¹ More than 80% of CVD mortality takes place in low- and middle-income countries (LMICs), despite their having lower prevalence rates compared with high-income countries (HICs).¹ Nevertheless, with the epidemiologic transition of LMICs away from infectious diseases and toward noncommunicable diseases, the burden of CVDs is anticipated to grow rapidly.^1,2 The Lancet Noncommunicable Diseases and Injuries (NCDI) Poverty Commission evaluated the burden of NCDIs in the world’s poorest billion, finding that lower socioeconomic status is associated with cardiovascular risk factors and greater morbidity and mortality due to CVD.² The global burden of CVDs is largely driven by ischemic heart disease. In LMICs, ischemic heart disease affects populations at younger ages than in HICs yet is still responsible for 13% of the total NCDI burden in adults older than 40 years among the world’s poorest billion. The Global Burden of Disease study has illustrated continued growing burdens of ischemic heart disease since 1990; estimates suggest that this burden will grow even further as the overall population grows, and the share of older people is expected to double in LMICs by 2050.³ Simultaneously, rheumatic heart disease affects >30 million people, especially in LMICs, where rheumatic heart disease remains highly prevalent and largely untreated.⁴ Moreover, >1 million children are born with congenital heart defects in LMICs each year, yet >90% do not receive the cardiovascular care they need.⁵ This vast global burden of cardiac surgical disease is compounded by the ongoing burden of endemic but neglected CVDs that commonly require timely cardiac surgical care, including endomyocardial fibrosis and Chagas cardiomyopathy.²

It is estimated that 1 to 1.5 million cardiac surgical procedures take place each year.⁶ However, little is known about country-level distribution or targets to meet the cardiac surgical burden in countries across all income groups. Barriers in infrastructure and workforce capacity are substantial in LMICs, requiring increased attention and efforts to bridge these remaining gaps. Here, we analyze current annual cardiac surgical volumes in HICs and propose targets for countries to work toward, ensuring cardiac surgical coverage for their populations.

Material and Methods

Gray literature was searched for HICs to identify reports presenting recent annual national volume data for cardiac surgical procedures. An unstructured literature search was performed using the PubMed/MEDLINE, Google Scholar, and World Health Organization Global Index Medicus databases with a combination of alternatives of the keywords cardiac surgery, volume, and [country name] for articles published between January 2010 and January 2021. The assumption was made that HICs almost completely meet the cardiac surgical needs of their population; by contrast, the lower workforce and cardiac center density, fragmented supply chains, and financial barriers in LMICs result in unmet cardiac surgical needs that vary by country. As such, inclusion of contemporary LMIC volumes would result in underestimates of needed cardiac surgical volumes.

Data were presented for total cardiac surgical volume, total coronary artery bypass grafting (CABG) volume, total valve surgery volume, and total congenital heart surgery volume. Volumes were presented per 100,000 population based on absolute numbers relative to the matched (by year) population for a given country. For HICs, the operative annual target was assumed to be the contemporary average of HICs. For LMICs, 2 scenarios were developed. First, based on expert consensus, the operative annual target was assumed to be half of the contemporary average of HICs per projections by Zilla and coworkers.⁷ In a second scenario, operative annual targets were set relative to the average burden of CVD for each income group category (ie, low income, lower middle income, and upper middle income) as described by the World Bank. Data sources are described in further detail in the Supplemental Material.

Results

Annual Procedural Volume

The average total cardiac surgical volume was 123.2 per 100,000 population per year (range, 27.3 in South Korea to 271.5 in the United States) for 24 countries with available data. The average CABG volume was 36.7 per 100,000 population per year (range, 7.7 in South Korea to 64.5 in the United States) for 35 countries. The average total valve surgery volume was 30.8 per 100,000 population per year (range, 12.7 in New Zealand to 55.2 in the United States) for 15 countries. The average total congenital heart surgery volume was 7.9 per 100,000 population per year (range, 1.2 in Singapore to 18.2 in the United Kingdom) for 18 countries. Table 1 summarizes annual volumes.

Table 1.

Annual Cardiac Surgical Volumes per 100,000 Population

Surgical Procedure	Procedural Volume per 100,000 Population per Year
	Average	Range
All cardiac surgery	123.2	27.3-271.5
Coronary artery bypass grafting	36.7	7.7-64.5
Valve surgery	30.8	12.7-55.2
Congenital heart surgery	7.9	1.2-18.2

Annual Volume Targets

Annual volume targets for HICs are similar to the average annual volumes. For LMICs, 2 scenarios are presented. Under the first scenario, annual volume targets per 100,000 population are as follows: 61.6 cardiac surgical procedures, 18.3 CABGs, 15.4 valve surgical procedures, and 4.0 congenital heart operations. For the second scenario, weights were used for low-income, lower-middle-income, and upper-middle-income countries to account for the current variation in the burden of CVD (Supplemental Table). Accordingly, annual total cardiac surgical volume targets per 100,000 population are as follows: 86.1 for upper-middle-income countries, 55.1 for lower-middle-income countries, and 40.2 for low-income countries (Figure 1). Table 2 summarizes annual volume targets by procedure and country income group.

Figure 1.

Estimated cardiac surgical volume per 100,000 population needed to cover population needs.

Table 2.

Targets for Annual Cardiac Surgical Volumes per 100,000 Population

Surgical Procedure	High-Income Countries	Low- and Middle-Income Countries	Low-Income Countries	Lower-Middle-Income Countries	Upper-Middle-Income Countries
	Scenario 1		Scenario 2
All cardiac surgery	123.2	61.6	40.2	55.1	86.1
Coronary artery bypass grafting	36.7	18.3	10.3	25.4	35.4
Valve surgery	30.8	15.4	15.8	10.5	13.3
Congenital heart surgery	7.9	4.0	15.6	13.0	10.1

Comment

The unmet needs in global cardiac care remain vast yet poorly quantified. To develop targets for countries to work toward, we identified an average annual cardiac surgical volume of 123.2 per 100,000 population in HICs. For LMICs, 61.6 (86.1 upper middle income, 55.1 lower middle income, 40.2 low income) procedures per 100,000 population per year are estimated to be needed to meet population needs.

In 2015, the Lancet Commission on Global Surgery proposed 6 key surgical indicators to assess the performance of health systems and longitudinally track indicators to quantify the progress made.⁸ Indicators included surgical volume, defined as surgical procedures performed per 100,000 population, and placing a target for all countries to achieve a minimum of 5000 procedures per 100,000 population per year.⁸ However, the Commission did not disaggregate indicators or targets by subspecialty. The World Health Organization recommended countries to achieve 400 open heart surgeries per million population per year, a target lowered to 40 per million population per year by the Pan-African Society for Cardiothoracic Surgery, given existing capacity gaps but not in light of existing population needs.⁹ Figure 2 summarizes all indicators and targets set by the Commission and our proposed targets for global cardiac surgery based on data from this study, previously published workforce data,¹⁰ and expert opinion. Achieving a certain cardiac surgical volume is a complex function of capacity (infrastructure and workforce), case detection (community health and primary care), and financial risk protection (insurance coverage), discussed in the Supplemental Material.

Figure 2.

Proposed 2030 and 2040 targets for the global surgery and global cardiac surgery communities, respectively. Adapted from¹⁰ with permission from Elsevier Ltd. ∗Recommendations are made for countries with a population of at least 500,000 people.

Our analysis highlights limited transparent reporting of aggregated and procedure-specific cardiac surgical volume data. Many HICs did not have data available for individual procedures, particularly valvular and congenital heart surgery, requiring greater public transparency. This may further inform variation in cardiac surgical volumes. For example, whereas congenital heart disease incidence rates are assumed to be stable globally, variations in congenital heart surgery volumes were observed per population unit, ranging from 1.2 per 100,000 population per year in Singapore to 18.2 in the United Kingdom. Although this may partially be the result of novel technologies (eg, minimally invasive procedures) being differentially adopted (Supplemental Material), this cannot explain the magnitude of variation, thus requiring further investigation into practice patterns and variations. Other CVD burdens vary widely between and within country income groups. For example, the burden of rheumatic heart disease is enormous in LMICs, whereas it is largely eradicated in HICs.⁴ Conversely, the older population in HICs presents with a larger burden of degenerative valvular disease compared with LMICs. As countries continue to address their communicable disease burdens and life expectancy continues to increase, it is likely that valvular disease transitions from predominantly rheumatic to predominantly degenerative causes. In addition, in LMICs, a nonnegligible amount of patients have been and continue to be operated on through visiting teams and nongovernmental organizations in settings where no or minimal local cardiac surgical services are in place. Here, more complex and delayed reinterventions may be needed. Whereas this number may be only a small fraction of the overall cardiac surgical need worldwide, these patients present with unique challenges to local health systems. Furthermore, procedural choices can substantially be influenced by the timing of presentation and patients’ background. For rheumatic heart disease, early presentation may allow balloon valvotomy or valvular repair, whereas more progressive disease or surgeons’ preference may result in the choice to replace valves. Last, individuals’ social determinants of health influence access to care and health outcomes within countries. Patients living in rural and remote communities have to travel greater distances to receive care, whereas within urban areas, poverty and cultural, gender, or religious identities also influence the time to seek, reach, and receive care. As such, increasing surgical volumes require efforts across all layers of the health system.

Our study carries some limitations, discussed in detail in the Supplemental Material. Briefly, countries have different socioeconomic, political, cultural, and health care setups (eg, reimbursement or adoption of transcatheter modalities), whereas populations differ in sociodemographics and genetic and ethnic characteristics, which may explain and require differential surgical volumes. In addition, we assumed that HICs meet the surgical needs of their populations, even though disparities may still exist in access to cardiac surgery in these countries. Last, sources of volume data varied, although they were consistent with the study methodology and excluded if sources were deemed to be invalid.

In conclusion, the global unmet needs for cardiac surgery are vast, especially in LMICs. Target annual procedural volumes present opportunities to strategically and specifically work toward expanding cardiac surgical capacity as part of countries’ progress toward universal health coverage.