Coronary artery disease and sauna

Coronary artery disease and sauna meet at the point where the circulatory work of the hot room meets a heart whose coronary vessels cannot always deliver the extra oxygen that work demands. The subject is important because coronary artery disease (CAD) — narrowing of the arteries supplying the heart muscle — is common in precisely the age group that visits saunas, and because the difference between a safe and an unsafe session lies in the stability of the disease and in the symptoms, not in the number of degrees of the room.

The load on the coronary heart

Bathing raises the heart rate and blood pressure in the pattern described under Heart rate in a sauna and Blood pressure in a sauna, and that rise increases the oxygen requirement of the heart muscle while shortening the time available for the coronary arteries to fill with blood between beats. A healthy coronary circulation copes easily; a narrowed one may not, and the classical result is angina — chest pain or tightness driven by the heart outrunning its blood supply. The risk of an unstable situation does not come from the mathematics alone but from its combination with the state of the disease: in stable CAD, in which the narrowing is constant and the person is symptom-free at rest, bathing at moderate temperature is regarded in the specialist reviews as tolerable for many patients, whereas unstable angina, a recent heart attack, or untreated symptoms change the picture completely.

The first line of guidance in the sauna literature is accordingly conservative: people with unstable angina or a recent myocardial infarction should not bathe at all until their clinician says otherwise, and anyone who develops chest pain, tightness, unusual breathlessness or a fluttering pulse during a session should stop immediately, cool down and seek medical advice without delay (see Medical advice before sauna and First aid in a sauna). Chest symptoms in the sauna are never "just the heat" — the heat is precisely their mechanism — and an episode that begins in the cabin and does not settle in the cooling room is a reason for emergency assessment (999 in the United Kingdom; the local emergency number elsewhere).

The evidence

Two lines of evidence describe the middle ground between prohibition and permissiveness. First, the Finnish cohort studies that underpin Cardiovascular effects of sauna report lower — not higher — rates of fatal cardiovascular outcomes among frequent bathers, and sudden deaths during sauna bathing are rare in the statistical record; the same studies are also the ones behind the association between frequent bathing and lower stroke and blood-pressure outcomes (see Sauna epidemiology). None of this is permissive for symptomatic patients, since cohort averages do not describe the individual with unstable disease. Second, small, supervised studies of the acute response — including measurement of blood-based markers of cardiovascular function after single sessions, and preliminary conference-level work at a cardiac rehabilitation institute on older adults with stable coronary disease — report that the acute load is handled by stable patients without distress and is accompanied by a transient improvement in some measures of vascular function. These are acute observations from supervised settings, not evidence that the sauna treats coronary disease, and they should be read as the research base for "stable patients can discuss bathing with their cardiologist", not for any self-directed programme (see Clinical sauna studies).

Medication and practical rules

Most people with CAD take medication that changes the heat response. Beta-blockers slow the heart and can blunt its ability to raise output in the heat; nitrates widen vessels and can worsen the fall in pressure on standing; and combined preparations act in both directions. Medication schedules should not be altered for a sauna visit, and the person's clinician should know that bathing is part of their routine (see Medication and sauna). The practical rules are the routine ones, with extra weight: moderate room temperature and moderate session length, no alcohol, hydration before and during, slow transitions, never bathing alone at the first sign of symptoms (see Going to a sauna alone), and respect for the facility's guidance (see Sauna safety).

It is worth stating what the evidence does not show. There is no trial establishing that sauna bathing prevents or improves coronary artery disease; the associations are observational; and the harmful potential of a session is concentrated exactly in the symptomatic patient who ignores their warning systems. For a person with CAD whose disease is stable and whose clinician approves, bathing is a tolerable pleasure; for the person with chest symptoms, recent events or unstable disease, the cabin is simply a place where a medical consultation should be arranged first (see Sauna contraindications).

See also

• Cardiovascular effects of sauna
• Arrhythmia and sauna
• Heart failure and sauna
• Medical advice before sauna
• Medication and sauna

References

• Laukkanen T, Khan H, Zaccardi F, Laukkanen JA. "Association between sauna bathing and fatal cardiovascular and all-cause mortality events." JAMA Internal Medicine 175(4):542–548, 2015. doi:10.1001/jamainternmed.2014.8187
• Laukkanen JA, Laukkanen T, Kunutsor SK. "Cardiovascular and other health benefits of sauna bathing: a review of the evidence." Mayo Clinic Proceedings 93(8):1111–1121, 2018. doi:10.1016/j.mayocp.2018.04.008
• Kunutsor SK, Häkkinen A, Zaccardi F, Laukkanen T, Lee E, Willeit P, Khan H, Laukkanen JA. "Short-term effects of Finnish sauna bathing on blood-based markers of cardiovascular function in non-naive sauna users." Heart and Vessels 33(8):1515–1524, 2018. doi:10.1007/s00380-018-1202-9
• Gravel H, Behzadi P, Barry H, Gagnon D. "Acute improvement of vascular function with Finnish sauna bathing in older adults with stable coronary artery disease." FASEB Journal 33(S1), abstract 838.7, 2019. doi:10.1096/fasebj.2019.33.1_supplement.838.7
• Kukkonen-Harjula K, Kauppinen K. "Health effects and risks of sauna bathing." International Journal of Circumpolar Health 65(3):195–205, 2006. doi:10.3402/ijch.v65i3.18102
• Ketelhut S, Ketelhut RG. "The blood pressure and heart rate during sauna bath correspond to cardiac responses during submaximal dynamic exercise." Complementary Therapies in Medicine 44:218–222, 2019. doi:10.1016/j.ctim.2019.05.002
• Heinonen I, Laukkanen JA. "Effects of heat and cold on health, with special reference to Finnish sauna bathing." American Journal of Physiology – Regulatory, Integrative and Comparative Physiology 314(5):R629–R638, 2018. doi:10.1152/ajpregu.00115.2017
• Hussain J, Cohen M. "Clinical effects of regular dry sauna bathing: a systematic review." Evidence-Based Complementary and Alternative Medicine 2018:1857413, 2018. doi:10.1155/2018/1857413