Evaluation of coronary blood flow reserve by N-13-NH3 positron emission computed tomography (PET) with dipyridamole in the treatment of hypertension with the ACE inhibitor (Cilazapril)

Purpose: The purpose of this study was to evaluate the effect of treatment with an angiotensin-converting enzyme (ACE) inhibitor (Cilazapril) for earl y hypertensive patients in terms of coronary blood now reserve evaluated by (NH3)-N-13-positron emission tomography (PET). Methods: Before and after 12 weeks of ACE inhibitor treatment, (NH3)-N-13-P ET with dipyridamole provocation test was performed, and definite myocardia l perfusion and coronary Row reserve (CFR) were calculated. Results: Compared to our normal subjects previously reported (2.61 +/- 0.74 ), average coronary flow reserve was decreased (1.70 +/- 0.64 in hypertensi ve patients), and improved after treatment (1.77 +/- 0.52), but not signifi cantly. Of 12 patients, five (42%) showed improved coronary flow reserve fr om 1.34 to 1.99 without a significant change in the resting flow. Only one patient (8%) showed deterioration after the ACE inhibitor treatment, The co ronary vascular resistance (CVR) after ACE inhibitor treatment of the patie nts with CFR < 2.0 decreased significantly compared with those with CFR <gr eater than or equal to> 2.0 (p < 0.03). Conclusions: These results indicate that hypertensive patients at the early stage show decreased coronary flow reserve despite having normal resting f low. Treatment with an ACE inhibitor (Cilazapril) for 12 weeks improved cor onary flow reserve in 42% of our patients. The CVR of the patients with CFR < 2.0 showed improvement compared to those with CFR greater than or equal to 2.0, This result indicates that an ACE inhibitor (e.g., Cilazapril) should be on e of the choices fur improving CFR if hypertensive patients in early stage show signs of ischemia or diastolic dysfunction, which may be one of the se quels of reserve restriction.