air pollution and heart disease

Yet another study found an increase in heart disease in people exposed to air pollution/fine-particulate matter exposure (see cad air pollution lancet2016 in dropbox, or doi.org/10.1016/ S0140-6736(16)00378-0). details:

--6795 participants. aged 45-84, enrolled in the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air) from 6 different US cities (Baltimore, Chicago, LA County, New York City, St Paul, Winston-Salem)
--median age 62, 53% women, 39% white, 12% Chinese, 27% black, 22% Hispanic), 50-80% with at least some post-high school education, 15% smokers, BMI 28, 45% with hypertension and SBP 128 mmHg, 12% diabetic, 15% on statins and cholesterol/HDL/LDL=190/50/115
--followed 10 years with repeated measurements of coronary artery calcium by CT (CAC score) as well as carotid artery intima-media thickness (CIMT); concentrations of fine particulate matter (PM2.5, which reflects particulate matter <2.5 mm in diameter) and nitrogen oxides (NOx) were estimated based on residence-specific spatio-temporal pollution concentration models, which include community-specific measurements, monitoring data and geographical predictors.
--baseline CAC was 145 Agatston units, which is already pretty elevated, but not so surprising for the demographics of the study (see https://www.mesa-nhlbi.org/Calcium/input.aspx for the MESA CAC score: input age, sex, race/ethnicity and CAC score to get a sense of the meaning of the score)

--results:
    --overall, CAC increased on average by 24 Agatston units/yr and CIMT 12mm/yr.
    --participant-specific air pollutant concentrations averaged over the years 2000-2010 ranged: for PM2.5 from 9.2-22.6 mg PM2.5/m3 and for NOx​ from 7.2-139.2 parts/billion (ppb) [PM2.5 highest in LA County, NOx highest in New York City]
    --for each 5 mg PM2.5/m3 increase, CAC progressed by 4.1 Agatston units/yr (CI 1.4-6.8), controlling for the usual suspects (age, sex, ethnicity, BMI, physical activity, smoking/second-hand smoke, employment, total and HDL cholesterol, triglycerides, statin use, neighborhood socioeconomic index, level of education, income)
    ​--for each 40 ppb increase in NOx, CAC progressed by 4.8 Agatston units/yr (0.9-8.7). this relationship was stronger in hypertensive, non-obese individuals and in those >65 yo.
    --no clear association with CIMT

commentary:
--there have been many studies over the past 1-2 decades finding a relationship between particulate exposure or air pollution with atherosclerotic disease (MI, strokes). the current study was a prospective long-term one which looked at the process of atherosclerosis itself. My reading of the literature is that CIMT is a much less accurate predictor of atherosclerotic events than the CAC (CIMT really measures arterial injury more than atherosclerosis itself). and CAC has really good sensitivity and specificity for clinical atherosclerotic events over an array of clinical settings (it' s the best of the nontraditional cardiac risk factors).
--this study provides strong evidence that the relationship between particulate exposure/air pollution and heart disease is mediated through atherosclerosis (vs simply being from endothelial dysfunction, arrhythmias, etc), that the process is dose-related and progressive, and that there would be a reasonable expectation that improving air quality would lead to improvements in atherosclerosis-related outcomes. Though I should add that there are also data from the MESA study that endothelial dysfunction may also play a role: see Krishnam RM. J Am Coll Cardiol 2012; 60:2158; and there was a small study at our health center in Boston finding an association between particulate exposure and cardiac autonomic function within hours of the exposure: see Lee M. Am J Cardiol 2016; 117:151)
--though I think this study is quite impressive regarding the relationship between air pollution and atherosclerosis, it would be interesting to see more granular data: was this as true for those with no underlying atherosclerosis by CAC at baseline? also, was there a difference in actual clinical events (vs just changes in the surrogate marker of CAC; though as a perspective, there are a slew of other studies finding increased strokes/MIs)?  
--so, again, on an individual level, it is useful to incorporate air quality as one of our many risk factors for clinical atherosclerotic disease both in terms of nonpharmacologic therapies (weight, diet, exercise, stress reduction, etc), perhaps with further education around minimizing exposure to air pollution on particularly bad days, and for use of meds (statins, etc). and, on a society level, and especially with increasing pollution in many countries associated with "modernization" and perhaps exacerbated further by climate change, this study reinforces the importance of public health initiatives to decrease air pollution/particulate exposures.



Comments

Post a Comment

if you would like to receive the near-daily emails regularly, please email me at gmodest@uphams.org

Popular posts from this blog

HDL a negative risk factor? or cholesterol efflux??

Although the data on HDL being protective of atherosclerotic disease is pretty consistent, there are negative studies, and the data on medications which dramatically improve HDL levels (eg, the cholesteryl ester transfer protein --CETP --inhibitors, such as torcetrapib) are clinically disappointing. there have been several explanations for this. for example, some HDL particles are "pro-inflammatory" and elicit an atherosclerotic response (which may be related to apolipoprotein C-III). a new article in NEJM highlights another angle -- that the issue is not the HDL number, but HDL's functionality in the reverse transport of cholesterol, as measured by the cholesterol efflux capacity (see  lipids HDL efflux capacity vs amt NEJM 2014 in dropbox, or  DOI: 10.1056/NEJMoa1409065). This article looks at the Dallas Heart Study, where they measured HDL levels, HDL particle concentrations, and cholesterol efflux capacity in 2924 adults free of cardiovascular disease and followed p
Read more

Drug company shenanigans: narcolepsy drug

I have not done a blog for a long time on drug company shenanigans. So it is my great pleasure to bring up a brand-new drug company approach to garner huge amounts of money (see  https://www.nytimes.com/2023/02/28/business/jazz-narcolepsy-avadel-patents.html?smid=nytcore-ios-share&referringSource=articleShare  ).  Based on an article by  Rebecca Robbins of the New York Times, who has written several articles on drug company excesses   As background, this will be my 42 nd  such blog: for the array, see  https://bucommunitymed.wpengine.com/page/4/?s=drug+company+shenanigans   Th e drug company  approach  this time  to extending  their  patents has a few “interesting” angles: -- this is a medication manufactured by Jazz Pharmaceuticals to treat narcolepsy: there are 2 versions: Xyrem and Xywav (Xywav has less sodium, so is marketed to those who should be on a low sodium diet). These meds are basically derivatives of gammahydroxybutyric acid (GHB)      -- the drug actually has a pretty
Read more

UPDATE: ASCVD risk factor critique

  I decided to do an extensive update of my prior ASCVD (atherosclerotic cardiovascular disease) risk analysis and critique of risk calculators, with much more information about the “non-traditional” risk factors. I felt that there should be more data/clarification, since I think we are really undertreating/not preventing the most common cause of death by relying on the ASCVD risk calculators   -- Cardiovascular risk models:      -- many of us rely on the various cardiovascular risk models to determine the appropriate approach to patients, and these are often integrated into the electronic medical records      -- these risk models have several very important limitations:          -- they are typically based on community data, eg from the Framingham study etc. But, in clinical practice, we are dealing with the individual and not the community:              -- there is very clear evidence that there are many individual risk factors that are associated with increased risk of a cardiovascu
Read more