medwireNews: Patients with hyponatremia tend to have worse disability and mortality after reperfusion therapy for acute ischemic stroke than those without hyponatremia, suggests a Dutch study.
According to the results, published in the European Journal of Neurology, patients who had hyponatremia when admitted to hospital for reperfusion therapy were 1.76 times more likely to have worse disability 3 months afterwards than patients with normal plasma sodium levels, and they also had a more than twofold higher mortality rate.
“Although our study is unable to address causality, it is conceivable that hyponatremia—at least in part—contributes to morbidity and mortality by negatively affecting the disease course in acute ischemic stroke,” write Anissa Pelouto (Erasmus Medical Center, Rotterdam) and colleagues.
Of 680 acute ischemic stroke patients analyzed in the retrospective study, 430 (63%) had received intravenous thrombolysis (IVT) with alteplase, 120 (18%) had received endovascular thrombectomy (EVT), and 130 patients had received both. The median age of the whole group was 73 years, 49% were women, and the median National Institutes of Health Stroke Scale score on admission was 5.
The participants’ median plasma sodium level at hospital admission was 139 mmol/L, with hyponatremia diagnosed in 92 (14%) patients, based on a plasma sodium concentration below 136 mmol/L. The majority (90%) of these patients had mild hyponatremia (130–135 mmol/L).
Hyponatremia was significantly associated with being older (median age of 77 vs 73 years), having hyperglycemia (44 vs 33%) and hypertension (76 vs 62%), and the of use diuretics (39 vs 27%) including thiazides (26 vs 15%).
At 3 months after reperfusion therapy, patients with hyponatremia had significantly worse neurological disability than those with normal sodium levels, with a median modified Rankin Scale (mRS) score of 3 versus 2, out of a possible 6. Additionally, 55% of patients with hyponatremia scored above 2 on the scale, indicating poor functional outcome, compared with 32% of patients with normal sodium levels.
The effect of hyponatremia was similar irrespective of whether patients received IVT, EVT, or both therapies.
The researchers note that patients with both hyponatremia and hypoglycemia had the highest risk increase for poor functional outcome, at 2.54-fold. This suggests that the two factors work synergistically to reduce the likelihood of recovery after stroke, they say.
Computed tomographic perfusion data, which was available for 20% of the patients, showed that those with hyponatremia had a significantly larger and more severe infarct in the brain tissue, as indicated by a significant 17.2 mL bigger ischemic core volume and a 55% greater core-to-penumbra ratio.
“Given that the use of reperfusion therapy for acute ischemic stroke is increasing and hyponatremia is both common and potentially modifiable, it is relevant to study its prognostic value for postreperfusion outcomes,” write Pelouto and colleagues.
They recommend further study of “the effects of rapid correction of hyponatremia using intravenous bolus hypertonic (3%) saline therapy,” on post-reperfusion outcomes.
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