Abnormal blood pressure circadian rhythm in acute ischaemic stroke: are lacunar strokes really different?

BACKGROUND

A pathologically reduced or abolished circadian blood pressure variation has been described in acute stroke. However, studies on alterations of circadian blood pressure patterns after stroke and stroke subtypes are scarce. The objective of this study was to evaluate the changes in circadian blood pressure patterns in patients with acute ischaemic stroke and their relation to the stroke subtype.

AIMS

We studied 98 consecutive patients who were admitted within 24 h after ischaemic stroke onset. All patients had a detailed clinical examination, laboratory studies and a CT scan study of the brain on admission. To study the circadian rhythm of blood pressure, a continuous blood pressure monitor (Spacelab 90217) was used. Patients were classified according to the percentage fall in the mean systolic blood pressure or diastolic blood pressure at night compared with during the day as: dippers (fall> or =10-20%); extreme dippers (> or =20%); nondipper (<10%); and reverse dippers (<0%, that is, an increase in the mean nocturnal blood pressure compared with the mean daytime blood pressure). Data were separated and analysed in two groups: lacunar and nonlacunar infarctions. Statistical testing was conducted using the SSPS 12.0. Methods We studied 60 males and 38 females, mean age: 70.5+/-11 years. The patient population consisted of 62 (63.2%) lacunar strokes and 36 (36.8%) nonlacunar strokes. Hypertension was the most common risk factor (67 patients, 68.3%). Other risk factors included hypercholesterolaemia (44 patients, 44.8%), diabetes mellitus (38 patients, 38.7%), smoking (24 patients, 24.8%) and atrial fibrillation (19 patients, 19.3%). The patients with lacunar strokes were predominantly men (P=0.037) and had a lower frequency of atrial fibrillation (P=0.016) as compared with nonlacunar stroke patients. In the acute phase, the mean systolic blood pressure was 136+/-20 mmHg and diastolic blood pressure was 78.7+/-11.8. Comparing stroke subtypes, there were no differences in 24-h systolic blood pressure and 24-h diastolic blood pressure between patients with lacunar and nonlacunar infarction. However, patients with lacunar infarction showed a mean decline in day-night systolic blood pressure and diastolic blood pressure of approximately 4 mmHg [systolic blood pressure: 3.9 (SD 10) mmHg, P=0.003; diastolic blood pressure 3.7 (SD 7) mmHg, P=0.0001] compared with nonlacunar strokes. Nonlacunar strokes showed a lack of 24-h nocturnal systolic blood pressure and diastolic blood pressure fall. The normal diurnal variation in systolic blood pressure was abolished in 87 (88.9%) patients, and the variation in diastolic blood pressure was abolished in 76 (77.5%) patients. On comparing lacunar and nonlacunar strokes, we found that the normal diurnal variation in systolic blood pressure was abolished in 53 (85.4%) lacunar strokes and in 34 (94.4%) nonlacunar strokes (P=nonsignificant). In terms of diurnal variation in diastolic blood pressure, it was abolished in 43 (69.3%) lacunar strokes and in 33 (91.6%) nonlacunar strokes (P=0.026).

CONCLUSIONS

Our results show clear differences in the blood pressure circadian rhythm of acute ischaemic stroke between lacunar and nonlacunar infarctions by means of 24-h blood pressure monitoring. The magnitude of nocturnal systolic and diastolic blood pressure dip was significantly higher in lacunar strokes. Besides, patients with lacunar strokes presented a higher percentage of dipping patterns in the diastolic blood pressure circadian rhythm. Therefore, one should consider the ischaemic stroke subtype when deciding on the management of blood pressure in acute stroke.