HEART-RATE-VARIABILITY AND N-3 FATTY-ACIDS IN PATIENTS WITH CHRONIC-RENAL-FAILURE - A PILOT-STUDY

Patients with chronic renal failure (CRF) often have autonomic cardiac dysfunction, which can be assessed by measuring heart rate variabilit y (HRV). This dysfunction prediposes the patients to sudden cardiac de ath. This study describes 24-hour HRV in patients with CRF compared to HRV in patients with a previous myocardial infarction (MI). Furthermo re, associations between HRV in patients with CRF and the content of n -3 polyunsaturated fatty acids (PUFA) in cell membranes were examined, because n-3 PUFA may improve HRV. Twenty-nine patients with CRF treat ed with dialysis were enrolled. A 24-hour Holter recording was obtaine d at baseline and the HRV variables, RR (= mean of all normal RR inter vals during the 24-hour recording and SDNN (= standard deviation of al l normal RR intervals in the entire 24-hour recording) were analyzed. Also, granulocyte fatty acid composition was determined. The patients were allocated to dietary supplementation with either 5.2 g of n-3 PUF A or a placebo oil (olive oil) daily for 12 weeks in a double-blind de sign. At the end of the supplementation period the Holter recording an d blood sampling were repeated. At baseline the CRF patients' mean SDN N was 86 ms compared to 118 ms (p <0.01) in patients with a previous M I. After supplementation with either n-3 PUFA or placebo a highly sign ificant correlation was observed between the content of n-3 PUFA in ce ll membranes and HRV (r = 0.71, p <0.01). Furthermore, when the patien ts were dichotomized according to their mean SDNN, it was found, that those with the highest SDNN had a higher content of n-3 PUFA in cell m embranes compared to those with the lowest SDNN (7.8% vs 4.2%, p <0.05 ). In conclusion, HRV was decreased in CRF patients indicating a cardi ovascular autonomic dysfunction. The positive correlation between the n-3 PUFA content in cell membranes and HRV suggests that the effects o f an increased intake of n-3 PUFA in CRF patients should be further st udied.