[Pathophysiology and prognosis in malignant hypertension: comparison by underlying diseases]

Pathophysiological characteristics and long-term prognosis were studied retrospectively in 69 malignant hypertensives associated with grade III or IV retinopathy and the diastolic blood pressure greater than 120 mmHg. Thirty three (48%) cases had essential hypertension (EHT) as the underlying disease, 26 (38%) as chronic glomerulonephritis (CGN), and the remaining 10 (14%) as others including chronic pyelonephritis, renovascular hypertension, hydronephrosis, multiple calyceal diverticula, and unknown original disease. The role of the renin-angiotensin system in malignant hypertension was investigated by measuring plasma renin activity (PRA) and determining the blood pressure response to angiotensin (ANG)II antagonist, (Sar1, Ile8) ANG II. Basal PRA was significantly higher in the EHT group than the CGN group, and the ANG II antagonist-induced reduction of blood pressure was only evident in the former group. The regression analysis revealed that PRA was linearly correlated with both mean blood pressure (MBP) and serum creatinine prior to antihypertensive treatment in the EHT group but not in CGN patients, although there was inverse correlation between PRA and serum sodium in both groups. Therefore, the renin-angiotensin system seems to play a significant role in elevating blood pressure and deteriorating renal function in malignant hypertension developed from EHT, while it is less important in that from CGN. The 5-year survival rate was 90% in total 69 patients with malignant hypertension, while the 5-year renal survival rate defined as the probability of surviving without maintenance hemodialysis was 37%, indicating that the treatment with hemodialysis as well as antihypertensive drug therapy contributed to an improvement of prognosis of malignant hypertension. The EHT group showed a poor prognosis for life compared with the CGN group, while in the latter group most patients rapidly developed endstage renal failure. Although the pretreatment serum creatinine levels were matched, the renal function more rapidly deteriorated after development of malignant hypertension in the CGN group than did in the EHT group, indicating renal survival rate to be shorter in the former group. Hence, underlying diseases may affect the long-term prognosis of malignant hypertension. The results obtained from this study suggest that the pathophysiological characteristics of malignant hypertension are different and its long-term prognosis is varied by underlying diseases such as EHT and CGN.