There are many paradoxes in cardiovascular medicine. These are where real life doesn't follow what 'everyone knows' is true. Indeed there are so many paradoxes that I would have thought that by now, the 'establishment' would have caught on to the fact (as I see it) that these paradoxes are not paradoxes, but examples of evidence that the accepted paradigm about raised cholesterol being the cause of a wide range of cardiovascular diseases is wrong, wrong, wrong!
But they don't, so to add to the many, already published 'paradoxes' another has just been published in the European Journal of Neurology. It is from research conducted at the Hospital del Mar, Barcelona. Paradoxically, it finds that patients with ischaemic stroke who have low cholesterol levels are more likely to die after a stroke than similar patients with higher cholesterol levels.
The research team measured cholesterol levels in 220 patients with ischemic stroke who underwent intravenous thrombolysis (clot-busting treatment) within 4.5 hours of symptom onset.
As expected, stroke severity, as measured on the National Institutes of Health Stroke Scale (NIHSS), was the most significant determinant of patient survival at 3 months in all models. However, the NIHSS score correlated inversely with patients' levels of total cholesterol, triglycerides, and LDL cholesterol (it did not correlate with HDL cholesterol).
Put another way, it means that higher total cholesterol levels were significantly associated with higher survival, and remained so after accounting for stroke severity. Three-month mortality, when total cholesterol was divided into tertiles (thirds) were as follows:
25.7% in the lowest tertile (<155 mg/dL; 4.0 mmol/L)
13.7% in the middle tertile (155-192 mg/dL; 4.0-4.9 mmol/L)
5.5% in the highest tertile (>192 mg/dL; 4.9 mmol/L).
25.7% in the lowest tertile (<155 mg/dL; 4.0 mmol/L)
13.7% in the middle tertile (155-192 mg/dL; 4.0-4.9 mmol/L)
5.5% in the highest tertile (>192 mg/dL; 4.9 mmol/L).
"Our study does not allow us to identify the reason why low cholesterol is associated with increased mortality after [ischemic stroke], although we could hypothesize that this is an epiphenomenon or a surrogate marker of poor prognosis rather than an effect related to cholesterol levels," they say. But they do note that cholesterol is essential for cell membrane function, and has many other important roles, making it "plausible" that high blood cholesterol levels could be neuroprotective.
The authors say that: "The mechanism of this apparent paradox, common to both ischaemic and haemorrhagic strokes, remains unexplained, and merits further research."
But they always say that - it keeps them in a job. What I would like to see researchers like these to say, just once, is "this increases the evidence base that having a low cholesterol levels is not healthy."
Roquer J, et al. Serum cholesterol levels and survival after rtPA treatment in acute stroke. Eur J Neurol. 2011 Dec 5. doi: 10.1111/j.1468-1331.2011.03607.x. [Epub ahead of print]
The authors say that: "The mechanism of this apparent paradox, common to both ischaemic and haemorrhagic strokes, remains unexplained, and merits further research."
But they always say that - it keeps them in a job. What I would like to see researchers like these to say, just once, is "this increases the evidence base that having a low cholesterol levels is not healthy."
Roquer J, et al. Serum cholesterol levels and survival after rtPA treatment in acute stroke. Eur J Neurol. 2011 Dec 5. doi: 10.1111/j.1468-1331.2011.03607.x. [Epub ahead of print]
