Saunas have been associated with increases in heart rate, changes in systolic blood pressure and ventricular ectopy. Electrocardiographic (ECG) changes have also been noted after patients have been exposed to the supraphysiologic temperatures in a sauna (usually greater than 80°C [176°F]). Giannetti and colleagues conducted a study to determine whether sauna use was well tolerated in patients with stable coronary artery disease (CAD).

Patients with known CAD, exercise-induced ST segment depression and reversible perfusion defects (on technetium-99m sestamibi scans) were included. Patients were excluded if they had a history of myocardial infarction, unstable angina or angioplasty within the previous three months.

Patients with heart failure, uncontrolled hypertension or ventricular arrhythmias were also excluded. The study consisted of three visits. At one visit patients underwent a symptom-limited exercise stress test and nuclear scintigraphy. In the exercise stress test, time to at least 1 mm ST segment depression, time to angina, total exercise duration and maximal ST segment depression were recorded. At another visit, each patient had a resting nuclear scintigraphic study. At another visit, patients sat for 15 minutes in a sauna where the temperature was between 85°C and 90°C (185°F to 194°F) and then underwent nuclear scintigraphy. Sauna use was discontinued if the patients developed symptoms, had a symptomatic drop in blood pressure, ST depressions of more than 3 mm or ventricular arrhythmias. Routine medications were not changed for this study.

Fifteen men and one woman (mean age: 63 years) participated in the study. One half of the patients had exertional angina and one half had silent ischemia. The sauna did not cause syncope or presyncope symptoms in any of the patients, although one patient left the sauna early because of fatigue. That patient's heart rate decreased from 78 to 64 beats per minute, which was deemed significant by the investigators. One patient reported feeling light-headed about five minutes after the sauna was finished and had an associated drop in systolic blood pressure and pulse rate. The latter changes were attributed to vagal reactions. Overall, there was a mean decrease in systolic blood pressure of 13 percent (± 6 percent) in the patients. Diastolic blood pressure did not change. Perfusion defect scores were calculated in 15 patients. Sauna use was not associated with significant ST-T wave changes, but 14 of the 15 patients had greater perfusion defects after the sauna than during rest. The sauna perfusion defects were highly correlated with the exercise defects.

The authors conclude that the asymptomatic ischemia that occurred in the sauna was well tolerated and was not as great as the ischemia that occurred during exercise. However, patients with stable CAD should still be cautioned about possible cardiac risks associated with sauna use.

In a related editorial, Leppo reasons that patients with CAD who are able to tolerate exercise can most likely tolerate the cardiac changes associated with use of a sauna. Stable patients who have no stress-induced ischemia and who have good exercise capacity could most likely be allowed to use saunas. Long-term cardiac risk is unknown.

editor's note: This study was quite small and only included patients with stable CAD. Patients with class III to class IV angina should be cautioned against use of saunas, and even patients with class I to class II angina should refrain from saunas and similar thermal activities. Patients whose risk of myocardial ischemia seems to be low should be advised, based on this study, to use saunas for no more than 15 minutes and certainly not to the point of symptoms.—g.b.h.