Montreal Heart Institute, Belanger Street 5000 East, Montreal, Quebec, Canada.
Can J Cardiol. 2010 Feb;26(2):e50-3. doi: 10.1016/s0828-282x(10)70007-6.
Cold temperature is known to commonly precipitate angina pectoris in patients with symptomatic coronary artery disease (CAD). It was previously shown that the ischemic threshold was lower during exercise testing at -8 degrees C than at +20 degrees C in patients with a history of cold-induced angina, whereas it was unchanged in patients without cold-induced angina. Few data exist on the impact of more severe cold exposure on myocardial ischemia.
To determine the effect of extreme cold exposure (-20 degrees C) on the ischemic threshold among CAD patients.
Thirteen men with CAD and documented exercise-induced ischemia performed two treadmill exercise tests, one at +20 degrees C and one at -20 degrees C, in random order. Electrocardiograms were recorded every 30 s and analyzed separately in random order by two experienced readers blinded to temperature.
The mean (+/- SD) time to ischemic electrical threshold was 53+/-60 s lower at -20 degrees C than at +20 degrees C (P=0.008), corresponding to a relative change of -8.0+/-10.5%. All other exercise parameters, including total exercise time and rate-pressure product, were unchanged during exposure to extreme cold.
Exposure to extreme cold (-20 degrees C) lowers the ischemic threshold during exercise testing in patients with CAD, even if asymptomatic or without a history of cold-induced angina. Patients with CAD and evidence of exertional angina or myocardial ischemia wishing to perform exercise at extremely low temperatures should discuss this matter with their physicians.
低温会诱发有症状的冠心病（CAD）患者心绞痛。先前的研究表明，有冷诱发心绞痛病史的患者在 -8°C 时运动试验的缺血阈值低于 +20°C，而无冷诱发心绞痛病史的患者则不变。关于更严重的寒冷暴露对心肌缺血的影响的数据较少。
确定 CAD 患者在极冷暴露（-20°C）下对缺血阈值的影响。
13 名有 CAD 病史且有运动引起缺血的男性患者，以随机顺序分别在 +20°C 和 -20°C 进行两次跑步机运动试验。每隔 30 秒记录心电图，并由两名经验丰富的读者以随机顺序进行分析，读者对温度不知情。
-20°C 时缺血电阈值的平均（+/-SD）时间比 +20°C 时低 53+/-60 秒（P=0.008），相对变化为-8.0+/-10.5%。所有其他运动参数，包括总运动时间和心率血压乘积，在极冷暴露期间都没有变化。
即使无症状或无冷诱发心绞痛病史，CAD 患者在寒冷暴露（-20°C）时运动试验中的缺血阈值会降低。有运动性心绞痛或心肌缺血证据且希望在极低温度下进行运动的 CAD 患者应与医生讨论此事。
