Angiotensin-Converting Enzyme Inhibitors, Angiotensin II Receptor Antagonists, and Symptomless Dysphagia

Symptomless dysphasia is one of the main causes of pneumonia in elderly people with stroke, and swallowing or the cough reflex can prevent aspiration pneumonia.1 The article by Nakayama and colleagues (May 1998),2 concerning angiotensin-converting enzyme (ACE) inhibitors and the swallowing reflex, was a fascinating and timely study. We previously reported that ACE inhibitors may cure symptomless dysphagia in hypertensive patients with stroke.3 ACE inhibitors and angiotensin II receptor antagonists (Ang II) are very important drugs for hypertensive patients. We investigated the prevention of symptomless dysphagia and treatment with different antihypertensive drugs in hypertensive patients with stroke. We investigated whether a correlation existed between patients with symptomless dysphagia with stroke and the elimination of low serum substance P concentration by ACE inibitors and Ang II.4 We excluded the immunocompromised patients. The subjects were 53 patients with hypertension, symptomless dysphagia, and history of stroke. They were divided into group A (32 patients; 13 men and 19 women) and group B (21 patients; 10 men and 11 women). We obtained informed consent from the patients or their families. To determine the occurrence of symptomless dysphagia, we gave 1 mL technetium tin colloid (99mTC) to patients in groups A and B during sleep via a nasal catheter.5 At 9:00 am the next day, we checked for symptomless dysphagia by imaging. We gave all patients in group A an ACE inhibitor (imidapril hydrochloride), 5 to 10 mg qd orally, and all patients in group B received Ang II (losartan potassium), 50 to 100 mg qd orally. We measured serum substance P before and 12 weeks after administration. The mean serum substance P before drug administration was 26.5 pg/mL in group A and 26.36 pg/mL in group B. After 12 weeks, symptomless dysphagia improved in 23 of 32 patients in group A. In these 23 patients, the mean serum substance P was 82.91 pg/mL. In six patients, symptomless dysphagia did not improve (mean serum substance P, 50.62 pg/mL) and in four of them, serum substance P was not increased (mean serum substance P, 46.12 pg/mL). Imidapril hydrochloride was stopped in the remaining patients because of excessive cough (mean serum substance P, 109.83 pg/mL). On the other hand, in all 21 patients in group B, symptomless dysphagia did not improve, and in all of them, serum substance P did not increase (mean serum substance P, 30.49 pg/mL) after 12 weeks (p , 0.0001). We concluded that ACE inhibitors have advantage over Ang II in prevention of symptomless dysphagia in patients with stroke.