Green at heart: can cardiology become more environmentally sustainable without compromising patient care?

This article won first prize in the recent British Junior Cardiologists’ Association (BJCA) essay competition.

Introduction

It is well known that climate change is increasing a plethora of environmental hazards detrimental to cardiovascular health. Rising temperatures, air pollution, and extreme weather events all elevate the incidence of myocardial infarction, stroke, arrhythmias, and heart failure.¹ As climate change worsens, cardiology as a specialty will face mounting pressure: overburdened clinicians and strained healthcare systems, ultimately leading to poorer patient outcomes. It is imperative that cardiology leads the healthcare sector in promoting sustainable practices, breaking the cycle by both mitigating its footprint and adapting to changing health needs.²

A straightforward, but profoundly impactful, change holds the key to making cardiology more sustainable: increasing awareness of the environmental impact linked to each clinical decision. Whether ordering a scan, selecting equipment, or choosing consultation types, attaching a carbon footprint estimate to each request provides clinicians with valuable information. This approach does not restrict their autonomy but empowers both clinicians and patients to make considered, sustainable choices.

Imaging

Cardiac imaging offers a clear first example. Evidence shows that transthoracic echocardiography has an emissions profile of only 1.5% compared with cardiac magnetic resonance imaging (MRI) and 14% compared with single-photon emission computed tomography (SPECT) imaging.³ Cardiac computed tomography (CT), often used for coronary artery calcium scoring and CT coronary angiography (CTCA), has a moderate environmental footprint, estimated at around 9.2 kg CO₂e (carbon dioxide equivalent) per scan, placing it between ultrasound and MRI.⁴ In the context of stable chest pain, CTCA is already recommended as the first-line investigation by the National Institute for Health and Care Excellence (NICE) guidelines, offering excellent diagnostic accuracy with a lower carbon cost compared with invasive angiography or perfusion imaging.⁵ MRI systems, by contrast, consume between 40 and 47 MWh/year, with 31–38% used during idle, nonproductive states.⁶ Implementing low-energy standby modes can reduce MRI energy use by a quarter to a third, with no impact on clinical output.⁶ Additionally, protocols, such as single‑breath‑hold cardiac MRI sequences, can shorten scan times and reduce scanner load.³ There is already evidence that certain imaging modalities may be overused in clinical practice. Studies examining the use of nuclear perfusion imaging and stress echocardiography have shown that 10–20% of scans may be clinically inappropriate or avoidable, particularly in low-risk or asymptomatic patients, where results seldom alter management.^7,8 Similarly, retrospective analyses indicate that cardiac MRI, while often used appropriately, is occasionally employed in settings where transthoracic echocardiography or CT would provide equivalent diagnostic value, at lower cost and carbon impact.^9,10 These examples underscore the value of making imaging carbon metrics visible, not to restrict clinical autonomy, but to enable more informed, patient-centred decisions that favour lower-impact options, like ultrasound or CT where appropriate, optimising the use of MRI without compromising diagnostic quality.

Equipment

Catheter laboratory equipment represents the second major area for improvement. Single-use plastics (catheters, drapes, syringes) contribute heavily to the carbon footprint of invasive cardiology. Lifecycle assessments demonstrate that reusable kits and textiles reduce climate impact by up to 90%, and primary energy demand by 65% compared with single-use alternatives.¹¹ Reprocessing electrophysiology catheters alone can reduce carbon emissions by 50–60% per use.¹¹ For example, an atrial fibrillation ablation generates approximately 77 kg CO₂e, comparable with a 420 km car journey.¹¹ Providing technicians and clinicians with such metrics during equipment selection would allow simple, high-impact choices, like opting for reusable stock, without compromising clinical safety or outcomes.

Remote follow-up

Remote reviews and monitoring is an area where cardiology is already leading the way. A global study involving over 32,000 patients with implantable devices showed that remote monitoring avoided 31.7 million travel miles over two years, saving more than 12,500 metric tons of CO₂e (12,500,000 kg CO₂e) and US $10 million in costs.¹² Another analysis estimated an average of 15 kg CO₂e saved per patient through remote pacemaker checks.² Teleconsultations in cardiology also contribute significantly, avoiding approximately 19 kg CO₂e per visit by reducing travel.¹³ However, it is important to recognise that face-to-face reviews remain essential for many patients, particularly those with complex symptoms, new diagnoses, or where physical examination and rapport are central to decision-making. The goal is not to replace all in-person care, but to use remote options judiciously, supported by visibility of their environmental benefits. Embedding carbon data into referral or discharge platforms would make these benefits a tangible, integrated part of shared decision-making.

Medication

Pharmaceuticals are a major source of healthcare emissions. Cardiology, a specialty heavily reliant on long-term pharmacotherapy, is well positioned to lead more sustainable prescribing. Lifecycle data show oral medications average around 1.5 kg CO₂e per box, but this can exceed 70 kg CO₂e for complex or branded drugs.^14,15 Simple changes, such as switching from intravenous to oral formulations when appropriate, can cut emissions dramatically. For example, intravenous paracetamol produces 0.628 kg CO₂e per dose compared with 0.038 kg CO₂e for the oral form.^14,15 Similar opportunities exist within cardiology, such as for intravenous diuretics and antibiotics. Up to 20% of older adults are prescribed potentially inappropriate cardiovascular medications, including unnecessary long-term loop diuretics or dual antiplatelet therapy.¹⁶ Regular medication reviews and deprescribing, not only improve safety, but offer environmental benefit. While more research is needed into the footprint of specific cardiovascular drug classes, optimising prescribing remains a low-effort, high-impact route to more sustainable care.

A strong clinical parallel comes from respiratory medicine, where raising awareness of environmental impact dramatically shifted prescribing practices. By publicising the carbon footprints of inhalers, a transition from pressurised metered-dose to dry-powder inhalers halved respiratory care emissions, with no loss of disease control.¹³ This highlights that when clinicians and patients know the environmental cost of each choice, they make different, yet still high-quality, decisions.

Conclusion

In conclusion, sustainable cardiology need not be complex or burdensome, it requires visibility. Every test, every device, every consultation needs a carbon label, not to constrain clinical autonomy or deny care but to enable truly shared decision-making that accounts for planetary health. When clinicians can see that a reusable catheter saves 2 kg CO₂e per use, or remote follow-up saves 15 kg CO₂e per patient, change becomes easy. Furthermore, transparency creates market incentives: device manufacturers and research funders will prioritise low-carbon solutions if carbon credentials are valued.

The data exist; tools can be integrated into electronic requesting systems and procedural checklists. Clinicians already care deeply for both patients and the planet. It is time to make carbon visible in cardiology’s heartbeat, simple, effective, empowering steps toward a sustainable future in cardiovascular care.

Key messages

• Carbon visibility empowers sustainable decision-making – adding carbon labels to imaging, procedures and prescriptions empowers clinicians to make informed, responsible choices
• Imaging techniques frequently used in cardiology have large variations in carbon footprints: ultrasound having the lowest emissions, computed tomography (CT) having a moderate footprint with strong diagnostic value, and magnetic resonance imaging (MRI)/nuclear imaging having the greatest environmental impact
• Cardiology are already leading the way in reducing emissions associated with outpatient follow-up. Remote monitoring of devices has reduced the environmental toll of travelling to clinic appointments, with the benefit of being more convenient for patients
• Sustainable prescribing is a high-impact intervention, which can have advantages for patients, especially the elderly population for whom polypharmacy can be a significant burden

Conflicts of interest

None declared.

Funding

None.

References

1. Khraishah H, Alahmad B, Ostergard RL Jr et al. Climate change and cardiovascular disease: implications for global health. Nat Rev Cardiol 2022;19:798–812. https://doi.org/10.1038/s41569-022-00720-x

2. Romanello M, Di Napoli C, Green C et al. The 2023 report of the Lancet Countdown on health and climate change: the imperative for a health-centred response in a world facing irreversible harms. Lancet 2023;402:2346–94. https://doi.org/10.1016/S0140-6736(23)01859-7

3. Marwick TH, Buonocore J. Environmental impact of cardiac imaging tests for the diagnosis of coronary artery disease. Heart 2011;97:1128–31. https://doi.org/10.1136/hrt.2011.227884

4. Gunasekaran S, Szava-Kovats A, Battey T et al. Cardiovascular imaging, climate change, and environmental sustainability. Radiol Cardiothorac Imaging 2024;6:e240135. https://doi.org/10.1148/ryct.240135

5. National Institute for Health and Care Excellence. Recent-onset chest pain of suspected cardiac origin: assessment and diagnosis. CG95. London: NICE, 2016. Available from: https://www.nice.org.uk/guidance/cg95

6. Chodorowski M, Ognard J, Rovira À, Gentric JC, Bourhis D, Salem DB. Energy consumption in MRI: determinants and management options. J Neuroradiol 2024;51:182–9. https://doi.org/10.1016/j.neurad.2023.12.001

7. Brindis RG, Douglas PS, Hendel RC et al. ACCF/ASNC appropriateness criteria for single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI): a report of the American College of Cardiology Foundation Quality Strategic Directions Committee Appropriateness Criteria Working Group and the American Society of Nuclear Cardiology endorsed by the American Heart Association. J Am Coll Cardiol 2005;46:1587–605. https://doi.org/10.1016/j.jacc.2005.08.029

8. Carr JJ, Hendel RC, White RD et al. 2013 appropriate utilization of cardiovascular imaging: a methodology for the development of joint criteria for the appropriate utilization of cardiovascular imaging by the American College of Cardiology Foundation and American College of Radiology. J Am Coll Cardiol 2013;61:2199–206. https://doi.org/10.1016/j.jacc.2013.02.010

9. Pontone G, Di Cesare E, Castelletti S et al. Appropriate use criteria for cardiovascular magnetic resonance imaging (CMR): SIC-SIRM position paper part 1 (ischemic and congenital heart diseases, cardio-oncology, cardiac masses and heart transplant). Radiol Med 2021;126:365–79. https://doi.org/10.1007/s11547-020-01332-6

10. Jaarsma C, Leiner T, Bekkers SC et al. Diagnostic performance of noninvasive myocardial perfusion imaging using single-photon emission computed tomography, cardiac magnetic resonance, and positron emission tomography imaging for the detection of obstructive coronary artery disease: a meta-analysis. J Am Coll Cardiol 2012;59:1719–28. https://doi.org/10.1016/j.jacc.2011.12.040

11. Meister JA, Sharp J, Wang Y, Nguyen KA. Assessing long-term medical remanufacturing emissions with life cycle analysis. Processes (Basel) 2022;11:36. https://doi.org/10.3390/pr11010036

12. Bawa D, Ahmed A, Darden D et al. Impact of remote cardiac monitoring on greenhouse gas emissions: global cardiovascular carbon footprint project. JACC Adv 2023;2:100286. https://doi.org/10.1016/j.jacadv.2023.100286

13. Wilkinson AJ, Braggins R, Steinbach I, Smith J. Costs of switching to low global warming potential inhalers. An economic and carbon footprint analysis of NHS prescription data in England. BMJ Open 2019;9:e028763. https://doi.org/10.1136/bmjopen-2018-028763

14. Davies JF, McAlister S, Eckelman MJ et al. Environmental and financial impacts of perioperative paracetamol use: a multicentre international life-cycle assessment. Br J Anaesth 2024;133:1439–48. https://doi.org/10.1016/j.bja.2023.11.053

15. Piffoux M, Le Tellier A, Taillemite Z, Ducrot C, Taillemite S. Carbon footprint of oral medicines using hybrid life cycle assessment. J Clean Prod 2024;475:143576. https://doi.org/10.1016/j.jclepro.2024.143576

16. Kim J, Han E, Hwang HJ et al. Potentially inappropriate prescribing of cardiovascular system and antiplatelet/anticoagulant drugs among elderly patients: a Korean population-based national study. J Geriatr Cardiol 2021;18:327–37. https://doi.org/10.11909/j.issn.1671-5411.2021.05.010