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Heart and summer heat: preventing cardiovascular risks thanks to new imaging technologies

A preventative approach, a true pillar

Periods of extreme heat are becoming increasingly frequent due to global warming. Beyond the well-known inconveniences, heat waves represent a significant public health challenge, particularly for patients with cardiovascular disease. According to the World Health Organization (WHO), excessive heat is responsible for thousands of deaths each year, a significant proportion of which are attributable to cardiac and circulatory complications.

In Switzerland, recent heat waves have highlighted this increased vulnerability. The Swiss League of Cardiology and the Federal Office of Public Health (FOPH) emphasize that periods of intense heat are associated with a significant increase in hospitalizations for myocardial infarction, decompensated heart failure, arrhythmias, and strokes. The IPCC's climate projections predict an increased frequency of these heat waves in the coming decades, thereby exacerbating the burden of climate-related cardiovascular diseases.

The pathophysiological mechanisms involved are numerous: dehydration, excessive vasodilation, decreased blood pressure, electrolyte imbalances, and overactivation of the sympathetic nervous system. All these factors can destabilize a weakened heart, whether it is coronary artery disease, heart failure, or hypertension. Faced with this emerging problem, cardiac imaging technologies now offer essential tools for better anticipating and preventing these complications during the summer months.

Diagnostic Imaging Center (CID Lausanne), precision cardiac imaging, combined with new predictive approaches based on artificial intelligence, allows for the detailed assessment of at-risk patients before the onset of clinical complications. This preventive approach is becoming a true pillar of modern cardiovascular medicine, particularly in the face of current climate challenges.

Are cardiovascular diseases aggravated by heat?

Acute myocardial infarction

Dehydration and high blood viscosity promote clot formation, increasing the risk of acute coronary events. Heat also puts significant strain on the heart, requiring increased cardiac output.

Decompensated heart failure

Peripheral vasodilation, combined with fluid losses, disrupts the fluid and sodium balance and can rapidly decompensate a patient already experiencing heart failure, leading to edema, dyspnea, and major fatigue.

Heart rhythm disorders

Electrolyte imbalances induced by excessive sweating and dehydration can trigger or worsen arrhythmias, particularly in patients with heart disease or implanted devices (pacemaker, defibrillator).

Strokes (CVA)

Although cerebral, this pathology is directly influenced by cardiovascular overload and dehydration, which promote thrombosis and cerebral embolism during periods of heatwave.

Hypotension and vasovagal syncope

The drop in blood pressure due to excessive vasodilation can cause lipothymia, loss of consciousness and falls, particularly in elderly subjects, those taking multiple medications or those with chronic hypotension.
The identified risk groups include the elderly, patients with chronic heart disease (coronary artery disease, heart failure, valvular heart disease), diabetics, patients with kidney failure, patients taking diuretics or antihypertensive medications, and athletes exposed to prolonged exertion in hot environments. Early identification of these risks, through cardiac imaging and appropriate functional assessments, allows for the implementation of targeted preventive measures before the arrival of hot weather.

Target audience and medical indications for summer cardiac imaging

Therefore, prevention through targeted cardiac imaging is primarily aimed at:

● To patients with known coronary artery disease, who have already experienced myocardial infarction or angina, in whom heat stress may precipitate a new acute event.

● For poorly controlled hypertensive patients, in whom summer blood pressure variations can lead to hypotension, rhythm disturbances or ischemic events.

● To people with chronic heart failure, even stabilized, in whom cardiac imaging assessment makes it possible to anticipate a possible decompensation due to overload.

● In diabetic subjects, whose cardiovascular risk is increased and often silent, making a summer coronary screening relevant (calcium score scan, coronary angiography scan).

● To patients treated with diuretics or beta-blockers, whose fluid and sodium balance and hemodynamic response are weakened by heat.

● For high-level athletes exposed to prolonged exertion in hot climates, where a cardiac assessment can ensure the safe resumption of summer activities.

Cardiac imaging plays a crucial role in these prevention strategies: it allows for the documentation of overall cardiac function, myocardial perfusion, coronary calcium load, and underlying rhythmic or structural abnormalities. This valuable information enables the early adaptation of treatments and preventive measures before the arrival of heat waves.

Detailed epidemiological data

Epidemiological data confirm that the cardiovascular impact of heat is underestimated in many populations. According to the WHO and recent studies in the Lancet Countdown on Climate Change and Health, heat waves are now responsible for tens of thousands of premature deaths each year in Europe, a major proportion of which are linked to heart and vascular diseases.

In Switzerland, reports from the Federal Statistical Office (FSO) show a clear seasonal increase in cardiovascular hospitalizations during heat waves. During the extreme heat events of 2003, 2015, and 2022, hospitalizations for heart attacks and heart failure increased by 10 to 20%, depending on the region. The Swiss League of Cardiology estimates that approximately 15 to 20% of excess summer mortality is directly attributable to cardiovascular complications.

The Swiss population presents increasing vulnerability factors: rapid demographic aging, high prevalence of hypertension (affecting nearly 25% of adults), expanding type 2 diabetes (more than 500,000 patients), and an increase in the number of coronary patients followed after angioplasty or cardiac surgery.

Internationally, large meta-analyses confirm an increased risk of cardiovascular disease as soon as the ambient temperature exceeds 30°C, with a cumulative effect over several consecutive days of heat. Some studies (Kunst et al., 2021; Gasparrini et al., 2017) estimate that a 1°C increase in summer temperatures is associated with a 2 to 4% rise in cardiac hospitalizations.

These robust epidemiological data reinforce the need for active preventive screening strategies, particularly among identified at-risk populations. Advanced cardiac imaging thus becomes a valuable triage tool during the summer months.

Artificial intelligence and preventive cardiovascular imaging

Automated detection of coronary calcifications

AI algorithms allow for ultra-precise quantification of coronary calcium, refining the assessment of individual coronary risk.

Predictive analysis of cardiac volumes and functions

AI measures ventricular volumes, ejection fraction and segmental kinetic abnormalities with high reliability, key elements in the prevention of cardiac decompensation in the event of heat stress.

Automated cardiovascular risk stratification

By integrating clinical, biological, and imaging data, AI systems can produce personalized risk scores, guiding preventative measures before the arrival of heat waves.

Assistance in screening for silent arrhythmias

Some automated Holter analysis systems allow for the early detection of episodes of atrial fibrillation or rhythm disturbances that may worsen under the effect of heat.

Facilitated longitudinal monitoring

AI software makes it possible to precisely compare successive examinations of a patient and to detect subtle changes that escape the human eye.
At the CID Lausanne, cardiac imaging equipment is progressively integrating these advanced analysis tools, under rigorous medical supervision. Artificial intelligence does not replace the specialist but enhances their ability to anticipate, secure, and personalize the care of patients most at risk of summer cardiovascular complications.

Patient journey at the CID Lausanne: a concrete example

At the Imaging and Diagnostic Center (CID Lausanne), each patient benefits from an individualized care pathway, tailored to their risk factors and summer sun exposure. Let's illustrate this with a few concrete situations encountered in practice:

Case 1: Mr. A., 68 years old, hypertensive and former smoker

In anticipation of the predicted heatwave, his doctor requested a preventative check-up at the CID. The cardiac CT scan revealed a moderate calcium score (Agatston 180), with no significant stenosis on the coronary CT scan. His antihypertensive medication was adjusted, and he was given instructions for hydration and temperature management, with enhanced monitoring planned for the summer months.

Thanks to imaging, his risk was better quantified and mitigated before the critical period.

Case 2: Mrs. B., 74 years old, heart failure stabilized on diuretics

Fearing a summer decompensation, his cardiologist ordered a follow-up echocardiogram at the CID. Left ventricular function remained intact, but mild overload was detected. His diuretic treatment was adjusted in advance of the anticipated heat wave.

Clinical monitoring is closely coordinated throughout the summer period.

Case 3: Mrs. D., 60 years old, type 2 diabetic under control

Coronary screening is recommended before the summer heat. The calcium score is high (Agatston 320), prompting the preventive initiation of a statin and antiplatelet therapy under cardiological supervision.

Without this imaging examination, this silent coronary vulnerability would have remained undetected. These examples illustrate the central role of preventive cardiac imaging in anticipating summer risks, protecting vulnerable patients, and avoiding complications that are often predictable when the assessment is carried out early enough.

Reference scientific studies

Numerous international studies support the link between summer heat and cardiovascular morbidity and mortality, and confirm the growing interest in preventive cardiac imaging in this context.

● Lancet Countdown on Climate Change and Health (2023) : This global report highlights a progressive and documented increase in cardiovascular mortality during recurring heat waves in Europe and around the world, underscoring the urgency of preventive approaches adapted to new climatic conditions.

● European Heart Journal (2022, Cheng et al.) : European multicenter meta-analysis demonstrating that an average increase of 1°C in summer temperature is associated with a 3% increase in hospital admissions for myocardial infarction and heart failure.

● Global Burden of Disease (GBD 2020) : The global analysis of environmental factors confirms that heat stress is becoming an emerging factor in the overall burden of cardiovascular diseases, now surpassing some classic factors in certain temperate regions.

● French CANICARD study (2019) : this national registry demonstrated a 15 to 20% increase in hospitalizations for acute coronary syndrome during prolonged heat waves, even in patients without known coronary artery disease, but carrying silent risk factors.

● Swiss League of Cardiology and FOPH (2022 national data) : In Switzerland, national data confirm excess cardiovascular mortality during the summer, with a high proportion of patients with hypertension, diabetes, and heart failure. The role of early screening is emphasized in the updated national guidelines.

All of this data points to a growing medical need: anticipating seasonal cardiovascular complications by integrating modern cardiac imaging tools and personalized monitoring strategies. The changing climate now necessitates an active adaptation of medical practices in Switzerland and across Europe.

Future perspectives and innovations

Preventive cardiovascular imaging is evolving rapidly, driven by technological advances and the increasing pressure of climate change. Several areas of innovation are expected to transform the management of patients exposed to summer cardiovascular risks in the coming years:

Development of ultra-low dose imaging

New generations of photon-counting cardiac scanners will further reduce radiological exposure, making preventive assessments even safer for repeated monitoring.

Integration of multi-criteria predictive AI

Beyond pure imaging, AI systems will integrate environmental factors (temperature, humidity, pollution), genetic data, clinical history and biological markers to calculate an individualized summer cardiovascular risk in real time.

Connected video surveillance during the summer period

Remote monitoring of at-risk patients using wearable sensors (blood pressure, heart rate, weight, hydration) will allow for early detection of the first signs of decompensation and adjustment of treatments before the onset of serious symptoms.

Multi-institutional collaborative platforms

Secure sharing of imaging and monitoring data between imaging centers, cardiologists, general practitioners and emergency services will allow for optimal responsiveness during heat waves.

Continuing education for professionals

The rapid evolution of knowledge requires a continuous training effort for Swiss radiologists, cardiologists and general practitioners on new preventive practices in the face of climate change.
The Lausanne Diagnostic Imaging Centre is firmly committed to this dynamic of innovation. By progressively integrating these cutting-edge tools and collaborating closely with partner cardiologists, the CID anticipates future needs and places cardiovascular prevention at the heart of its mission, particularly in a climate context that makes this approach increasingly essential.

The differentiating strengths of CID Lausanne

The Lausanne Diagnostic Imaging Centre (CID) distinguishes itself through an innovative and rigorous preventive approach, perfectly adapted to the specific challenges faced by Swiss patients in the face of summer cardiovascular risks:

● Latest generation technologies : low dose cardiac scanners, high-end MRI and D-Spect allow for a comprehensive risk assessment before the arrival of heat waves.

● Gradual integration of artificial intelligence : AI-assisted analysis solutions improve the quantification of coronary calcifications and the early detection of functional abnormalities, while remaining under FMH medical supervision.

● Rapid access and organizational flexibility : short appointment slots, priority circuits for vulnerable patients before the summer period and close coordination with referring cardiologists ensure rapid and smooth care.

● Swiss multidisciplinary expertise : FMH radiologists specializing in cardiovascular imaging and cardiology partners ensure expert interpretation and individualized therapeutic decision-making.

● Compliance with Swiss quality standards (FOPH, FMH, LaMal) : conformity to radiation protection requirements, transparency of medical indications and reimbursement within the framework of services recognized by LAMal.

● Positioning in active prevention : the CID Lausanne does not limit itself to a curative diagnosis but offers real preventive support for cardiovascular patients vulnerable to climate change.

This strategic positioning allows CID Lausanne to offer unique expertise in French-speaking Switzerland in the early securing of patients exposed to increasing summer cardiovascular risks.

FAQs for patients and professionals

Who should consider a preventative cardiac check-up before summer?

Patients with coronary artery disease, hypertension, heart failure, diabetes, those taking diuretics or beta-blockers, as well as athletes exposed to prolonged exertion in high temperatures.

Is artificial intelligence replacing the cardiologist?

No. AI assists in image analysis and refines early detection, but the medical decision remains fully supervised and validated by experienced FMH specialists.

When is the best time to carry out this preventative check-up?

Ideally a few weeks before the arrival of the first major summer heat, in order to adjust treatments and anticipate individual risks.

Why the heat

Does it increase cardiovascular risks?

 Extreme heat causes dehydration, vasodilation and electrolyte imbalance, putting more strain on the heart, especially in patients who are already frail.

Is preventive cardiac imaging reimbursed in Switzerland?

Yes, according to justified medical indications and on prescription from the attending physician, in accordance with the standards of the LAMal and the recommendations of the Swiss League of Cardiology and the FOPH.