Use of RAAS blockers in patients with malignant hypertension and thrombotic microangiopathy: A series of clinical observations

Abstract

Malignant arterial hypertension (MAH) is a medical emergency characterized by severe elevation of blood pressure (BP; typically, >180/120 mmHg) accompanied by acute target-organ damage involving the kidneys, central nervous system, eyes, and/or heart. The severity and duration of arterial hypertension are important determinants of survival. Without adequate treatment, the prognosis is poor, with up to 80% of untreated patients dying from cardiovascular complications within two years. Current management requires an urgent but controlled reduction in BP to minimize the risk of irreversible organ damage. This article analyses five clinical cases of MAH. In all patients, the increase in serum creatinine (sCr) met the criteria for acute kidney injury (AKI), while kidney biopsy revealed chronic or combined acute and chronic thrombotic microangiopathy (TMA). Renin–angiotensin–aldosterone system (RAAS) inhibitors, including angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers, were successfully incorporated into antihypertensive therapy in all cases. RAAS inhibitors can interrupt the pathological cycle of elevated BP, renal ischemia, RAAS activation, further BP elevation, and TMA. Nevertheless, their initiation in patients with hypertension and kidney dysfunction is often delayed because of concerns about worsening AKI or progression of chronic kidney disease (CKD). Current clinical guidelines recommend caution when using these agents during acute kidney dysfunction and in advanced CKD. In all five cases, combination therapy including a RAAS inhibitor achieved the target BP. Treatment was well tolerated and not associated with hyperkalemia or worsening azotemia. Thus, RAAS inhibitors may be effective and safe in patients with MAH, including those with severe kidney injury. Their use can help control BP, improve prognosis, and reduce the risk of life-threatening cardiovascular complications. As evidence supporting the successful use of these agents in MAH associated with TMA accumulates, current restrictions on their use may be reconsidered, potentially helping to prevent the progression of kidney failure in patients with this severe condition.