Introduction: Our study aims at identifying and quantifying the relationship between the cold and heat exposure and the risk of cardiovascular mortality through a systematic review and meta-analysis. Material and Methods: A systematic review and meta-analysis were conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Peer-reviewed studies about the temperature and cardiovascular mortality were retrieved in the MEDLINE, Web of Science, and Scopus databases from January 2000 up to the end of 2015. The pooled effect sizes of short-term effect were calculated for the heat exposure and cold exposure separately. Also, we assessed the dose–response relationship of temperature-cardiovascular mortality by a change in units of latitudes, longitude, lag days and annual mean temperature by meta-regression. Result: After screening the titles, abstracts and full texts, a total of 26 articles were included in the meta-analysis. The risk of cardiovascular mortality increased by 5% (RR, 1.055; 95% CI [1.050–1.060]) for the cold exposure and 1.3% (RR, 1.013; 95% CI [1.011–1.015]) for the heat exposure. The short-term effects of cold and heat exposure on the risk of cardiovascular mortality in males were 3.8% (RR, 1.038; 95% CI [1.034–1.043]) and 1.1%( RR, 1.011; 95% CI [1.009–1.013]) respectively. Moreover, the effects of cold and heat exposure on risk of cardiovascular mortality in females were 4.1% (RR, 1.041; 95% CI [1.037–1.045]) and 1.4% (RR, 1.014; 95% CI [1.011–1.017]) respectively. In the elderly, it was at an 8.1% increase and a 6% increase in the heat and cold exposure, respectively. The greatest risk of cardiovascular mortality in cold temperature was in the 14 lag days (RR, 1.09; 95% CI [1.07–1.010]) and in hot temperatures in the seven lag days (RR, 1.14; 95% CI [1.09–1.17]). The significant dose–response relationship of latitude and longitude in cold exposure with cardiovascular mortality was found. The results showed that the risk of cardiovascular mortality increased with each degree increased significantly in latitude and longitude in cold exposure (0.2%, 95% CI [0.006–0.035]) and (0.07%, 95% CI [0.0003–0.014]) respectively. The risk of cardiovascular mortality increased with each degree increase in latitude in heat exposure (0.07%, 95% CI [0.0008–0.124]). Conclusion: Our findings indicate that the increase and decrease in ambient temperature had a relationship with the cardiovascular mortality. To prevent the temperature- related mortality, persons with cardiovascular disease and the elderly should be targeted. The review has been registered with PROSPERO (registration number CRD42016037673).

The relationship between apparent temperature and cardiovascular disease (CVD) mortality was studied in Rasht, Iran, from 2005 to 2014. The effects of apparent temperature on CVD mortality were investigated using the distributed lag nonlinear model. Data on all types of cardiovascular mortality cases according to the International Classification of Diseases were collected from the only cardiovascular hospital in Rasht, and the meteorological variables were obtained from Rasht Meteorological Center during the period of study. Our findings showed that low temperatures had significant impacts on CVD mortality, and a reverse J-shaped temperature-mortality relationship was found. Moreover, immediate effects of hot temperatures on CVD mortality with the strongest effects on the same day but delayed effects of cold temperature was observed. This study showed that exposure to both hot and cold apparent temperatures was associated with increased cardiovascular mortality in Rasht.

Acute myocardial infarction (AMI) is one of the most preventable non-communicable diseases in human. Identifying triggers of myocardial infarction (MI) and prevention ways of exposure-induced complications can reduce morbidity and mortality in people at risk. The aim of this study was to identify the emotional, environmental, physical and chemical dimensions of acute triggers in patients with AMI. This case-crossover study was conducted on 269 patients with AMI, hospitalized at two remedial centers in Rasht in 2015. The study samples were selected by convenient sampling method. Data were collected using researcher-made questionnaire through interviews. Hazard and control periods for each trigger and its effects on the development of MI were studied. The collected data were analyzed using descriptive and analytical statistical methods, Cochran test, and generalized estimating equation (GEE) model with logistics function default in SPSS version 21, and p < 0.05 was considered statistically significant. The results showed that quarrel (P = 0.008, OR = 2.01) and hearing the sudden news (P = 0.001, OR = 2.19) were the most common emotional triggers. Respiratory infections (P = 0.0001, OR = 6.78) and exposure to hot or cold weather (P = 0.005, OR = 2.19) were the most frequent environmental triggers. Doing heavy activities (P = 0.005, OR = 1.66) and sexual activities (P = 0.003, OR = 2.36) were among the most common physical triggers. High-fat foods consumption and overeating (P = 0.0001, OR = 3.79) were the most frequent chemical triggers of AMI. It seems that given the importance of the triggers in the incidence of AMI, planning is necessary to train vulnerable individuals to reduce exposure to triggers.

The Medical Journal of the Islamic Republic of Iran (MJIRI), is a quarterly and an editorially independent publication owned by Iran University of Medical Sciences and aims to be a publication of international repute for reporting current regional and international adventures in all aspects of the medicine. MJIRI welcomes contributions in this field in the form of original research articles, case reports, letter to the editor, review articles, brief communications, debate articles, and study protocols.