A Meteorological Paradox: Low Atmospheric Pressure-Associated Decrease in Blood Pressure Is Accompanied by More Cardiac and Cerebrovascular Complications: Five-Year Follow-Up of Elderly Hypertensive Patients

Background: Variations in atmospheric pressure (AP) are known to affect blood pressure (BP). We assessed the effect of AP on BP, and the major fatal and nonfatal complications thereof (i.e., stroke, myocardial infarction, and pulmonary emboli). Methods: In this observational cohort study, 250 hypertensive patients (aged 65–92 years old) were followed for 3.5–5.4 years in a primary care clinic. Cox proportional hazard regression was performed to define the associations between AP, clinical, demographic and environmental factors, and major complications such as stroke, myocardial infarction, etc. Results: AP fluctuated between 1007 and 1024 millibars (MB). A total of 132 patients (53%) developed various complications, of which 13 (9.8%) were fatal. Among all fatalities, 93 of 119 nonfatal cases and 7 of 13 fatal cases occurred at AP < 1013 MB. A Cox regression analysis showed that low AP (AP < 1013 MB) had a higher hazard ratio (HR) on hypertension (HTN) complications among all demographic, clinical and environmental parameters. Conclusions: Most major complications were associated with very low APs. Low AP was the best predictive risk-factor for major complications of HTN.