Over two million pilgrims perform annual rituals in Makkah region, which when coincides with summer months, exposes them to outdoor temperatures exceeding 45 °C and humidity approaching 80%. Accordingly, heat illnesses are common including explicit heat strokes and heat exhaustion. No previous studies elaborated on electrocardiographic changes among this unique cohort.
Objective: To compare electrocardiographic changes in three groups exposed to high outdoor temperatures, namely, patients with heat stroke compared to patients with heat exhaustion and a control group exposed to the same outdoor temperatures without clinical manifestations.
Subjects and methods: Through case control design, two case groups of patients were selected. The first group (G1) was 34 patients admitted to the cooling units with clinical picture of heat stroke and the second group (G2) comprised 28 patients admitted with heat exhaustion. The control group (G3) included 31 patients selected from relatives of patients and outdoor workers. The outcome for comparison was 12-lead electrocardiographic changes done for all selected individuals. For (G1), the ECG was done while they were prepared for cooling or immediately when cooling was started.
Results: In G1, 18 were females and 16 males with ages of 20-76 years (59 ± 11 years). Their heart rates ranged from 64 to 160 beats per minute (mean 120 ± 24 per minute). Only 5/34 ECGs were completely normal. Sinus tachycardia was present in 27/34 patients (79%), with ischemic changes in 9/34 ECGs. In G2, 24 were males and four females with ages of 25-80 (mean 47 ± 15 years), the heart rate ranged from 64 to 170 per minute (mean 97 ± 16 per minute). Seven out of 28 ECGs were normal (25%) while 21/28 had some abnormalities. None had ischemic changes. Control group (G3), was five females and 26 males ages 18-80 years (mean 38 ± 15 years), 22/31 had normal ECGs (71%). All had normal sinus rhythm, 56-98 beats per minute (74 ± 11). Nine patients had some electrocardiographic abnormalities but none had ischemic changes.
Conclusion: We conclude that electrocardiographic abnormalities occur with a high frequency in patients with heat stroke and heat exhaustion, with sinus tachycardia and ischemic changes occurring more frequently in patients with heat stroke.
Keywords: Electrocardiography; Heat exhaustion; Heat stroke; Pilgrims.