Advance Publication The Journal of Veterinary Medical Science Accepted Date: 3 Jun 2018 J-STAGE Advance Published Date: 22 Jun 2018 1 1 FULL PAPER, Internal medicine 2 Effects of the angiotensin-converting enzyme inhibitor alacepril in dogs with mitral 3 valve disease 4 5 Yasutomo Hori1), Kensuke Nakamura2), Nobuyuki Kanno3),Makoto Hitomi4), Yohei 6 Yamashita5,6), Satoshi Hosaka7), Noriko Isayama8) and Takahiro Mimura9) 7 8 1) School of Veterinary Medicine, Rakuno Gakuen University, 582 Midori-machi, 9 Bunkyodai, Ebetsu, Hokkaido 069-8501, Japan. 10 2) University of Miyazaki, 1-1 Gakuenkibanadai-nishi, Miyazaki, 889-2192 Japan. 11 3) Veterinary Internal Medicine, Department of Veterinary Medicine, College of 12 Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa 13 252-8510, Japan. 14 4) Hitomi Animal Hospital, 37-7 Yoshidakamiadachicho, Sakyo, Kyoto, 606-8307, 15 Japan. 16 5) Ebisu Animal Hospital, 3-3-43 Nishitaga, Taihaku, Sendai, Miyagi 982-0034, 17 Japan. 18 6) Laboratory of Small Animal Internal Medicine II, School of Veterinary Medicine, 19 Kitasato University, 23-35-1 Higashi, Towada, Aomori 034-8628, Japan 20 7) Hosaka Animal Hospital, 4-17-1 Nihonmatsu Midori, Sagamihara, Kanagawa, 21 252-0137, Japan. 22 8) Uenonomori Animal Clinic, 1-5-11 Yanaka Taito, Tokyo, 110-0001, Japan. 23 9) Olieve Animal Medical Center, 12-5 Shinomiyakandacho, Yamashina, Kyoto 24 607-8035, Japan. 25 26 Address correspondence to: Yasutomo Hori 27 School of Veterinary Medicine, Rakuno Gakuen University, 582 Midori-machi, 28 Bunkyodai, Ebetsu, Hokkaido 069-8501, Japan. 29 E-mail: [email protected] 30 31 RUNNING HEAD: EFFECTS OF ALACEPRIL IN DOGS 1 2 32 ABSTRACT 33 Alacepril is a relatively novel angiotensin-converting enzyme inhibitor; however, the 34 safety, tolerance, and efficacy of alacepril in terms of cough suppression in dogs with 35 mitral valve disease (MVD) remain unknown. The aim of this study was to investigate 36 the safety, tolerance, and cough suppression efficacy of alacepril in dogs with MVD. 37 This was a multi-center, prospective study. Forty-two dogs with echocardiographic or 38 radiographic evidence of cardiac enlargement in addition to cough were enrolled. Dogs 39 were treated with alacepril (1.0‒3.0 mg/kg/day) for at least 4 weeks. One dog (2.4%) 40 developed complications, including appetite loss, lethargy, and vomiting. Thirty-six 41 dogs were re-evaluated after 4 weeks of treatment. Cough resolved or improved in 20 42 dogs (55.6%) after treatment. Based on the efficacy of alacepril, the dogs were divided 43 into an effective group (n = 20) and an ineffective group (n = 16). After treatment, the 44 left ventricular end-diastolic internal diameter corrected for body weight was 45 significantly increased from baseline in the ineffective group but was significantly 46 decreased in the effective group. Univariate binomial logistic regression analyses 47 showed that high atrial natriuretic peptide level, N-terminal pro-B-type natriuretic 48 peptide level, and E wave velocity at baseline were significantly correlated with 49 alacepril inefficacy. Alacepril as treatment for MVD is well tolerated in most dogs, and 50 different conditions of cardiac loading may influence the effect of the drug. Alacepril is 51 expected to improve the quality of life of dogs with early stage MVD. 52 53 KEYWORDS: alacepril, canine, cough, heart failure, vasodilator 2 3 54 Mitral valve disease (MVD), secondary to degeneration of the mitral valve, is the 55 most common acquired cardiac disease and cause of heart failure in dogs. Heart failure 56 is a complex clinical syndrome characterized by symptoms such as exercise intolerance, 57 dyspnea, respiratory effort, and fatigue [5, 6, 14]. Affected dogs may ultimately develop 58 left-sided congestive heart failure (CHF), especially in association with pulmonary 59 edema, and the prognosis for these dogs is very poor [6]. In addition, cough is the most 60 common complication of MVD even in dogs without CHF [12, 16, 36]. Both mainstem 61 bronchial compression and cardiac enlargement are common sequelae of MVD and 62 appear to interact with cough in a complex manner [36, 37]. 63 Several angiotensin-converting enzyme (ACE) inhibitors are available clinically, 64 and they are divided into two groups according to the presence of sulfhydryl; 65 furthermore, captopril, zofenopril, and alacepril contain sulfhydryl groups. The presence 66 of a sulfhydryl group may confer useful properties such as an antioxidant effect and 67 enhancement of vascular endothelial nitric oxide production [24, 27, 28, 30]. Such 68 effects may improve vascular endothelial function and encourage vascular remodeling 69 [28, 30, 31]. In addition, the effects of alacepril are mediated by its metabolites, 70 captopril and deacetyl-alacepril [25, 40]. Alacepril exerts potent and prolonged ACE 71 inhibition compared with captopril [38-40]. In addition to vasodilation [26, 40, 43], 72 laboratory studies have demonstrated that alacepril restores myocardial 73 beta-adrenoceptor density and norepinephrine content in the failing myocardium [43], 74 while deacetyl-alacepril exerts long-lasting antihypertensive effects [25, 40] and inhibits 75 norepinephrine secretion from the isolated artery [26]. Alacepril attenuated sympathetic 76 activation and enhanced the arterial baroreflex in human patients with heart failure [22]. 77 As with other cardiac diseases, the renin‒angiotensin‒aldosterone system is 3 4 78 activated in dogs with MVD [32]. Previous studies demonstrated that ACE inhibitors 79 attenuated myocardial fibrosis in animal models of heart failure [11, 42]. 80 Pharmacological blockade of ACE plays a significant role in the management of heart 81 failure in humans [20]. Although a recent retrospective study showed that ACE 82 inhibitors prolonged the survival time in dogs with asymptomatic MVD [33], no 83 prospective studies have shown that ACE inhibitors delay the onset of CHF and prolong 84 the survival time in dogs with MVD [4, 10, 14, 15]. Furthermore, the use of ACE 85 inhibitors to treat dogs with asymptomatic MVD, i.e., American College of Veterinary 86 Internal Medicine (ACVIM) stage B2, remains controversial [3, 12]. 87 Although a few studies have investigated the effects of alacepril in laboratory 88 dogs [21, 34], clinical information of alacepril in dogs with spontaneous MVD is 89 lacking. The objectives of the current study were to investigate the safety and tolerance 90 of alacepril in dogs with MVD and to determine whether alacepril improves clinical 91 symptoms, i.e., cough, in dogs with MVD in ACVIM stage B2. 92 93 MATERIALS AND METHODS 94 This was a prospective multi-center study. All dogs were examined between 95 August 2015 and July 2016. The study was conducted in accordance with the 96 experimental animal guidelines of the Japanese Ministry of Education, Culture, Sports, 97 Science and Technology. Owners provided informed consent before their dogs 98 participated in the study. 99 100 Dogs: A total of 42 dogs (20 males and 22 females) aged 4.5‒16.0 years and weighing 101 2.4‒12.0 kg were enrolled in the study. All dogs underwent physical examination, 4 5 102 echocardiography, thoracic radiography, and blood sampling, all of which were 103 performed without sedation in a quiet examination room. All owners were asked 104 detailed questions on whether their dogs had received previous treatment for 105 cardiovascular disease. 106 Inclusion criteria for dogs with MVD were at least a grade 3/6 heart murmur and 107 confirmation of mitral valve regurgitation on echocardiography. Dogs had 108 echocardiographic or radiographic evidence of cardiac enlargement, i.e., ACVIM stage 109 B2 [3]. In detail, dogs that met two or more of the following criteria were regarded as 110 stage B2: vertebral heart scale (VHS) score of ≥10.5, left atrial-to-aortic diameter ratio 111 (LA/Ao ratio) of ≥1.6, and left ventricular end-diastolic internal diameter corrected for 112 body weight (LVIDDN) of ≥1.7 [3, 7]. Furthermore, to investigate the suppression of 113 cough by alacepril, only dogs with a cough were included. Following the initial 114 examination, dogs were treated with alacepril (1.0‒3.0 mg/kg/day, once-daily oral 115 administration; Apinac, DS Pharma Animal Health, Osaka, Japan) for at least 4 weeks. 116 The alacepril dose was not changed during the study. Each dog was examined at the 117 time of enrollment and after treatment. Cough was scored based on the owner’s 118 assessment (Table 1). After data collection, subgroup analyses were conducted based on 119 the improvement in total cough score. The dogs were divided into an effective group if 120 the total cough score improved by ≥1 after treatment and into an ineffective group if the 121 total cough score did not improve. The clinician was not blinded to the dog’s history or 122 the echocardiography results. 123 Exclusion criteria for the study were asymptomatic dogs without cardiac 124 enlargement (ACVIM stage B1), and dogs with current or past cardiogenic pulmonary 125 edema (ACVIM stage C). Other exclusion criteria were concurrent systemic illness in 5 6 126 addition to cardiovascular disease such as pulmonary, endocrine, renal, hepatic, or 127 inflammatory diseases or malignancies. In addition, dogs that exhibited an obvious 128 respiratory disease, such as tracheal collapse, bronchomalacia, pneumonia, laryngeal, or 129 thoracic cavity disease, and/or a lung tumor were excluded after thoracic radiography. 130 131 Thoracic radiography and echocardiography: The cardiothoracic ratio and VHS 132 score were evaluated using thoracic radiography according to a previously described 133 method [8, 17]. Transthoracic echocardiography was performed by experienced 134 echocardiographers using an ultrasonographic unit with a 7.5- to 12-MHz probe. MVD 135 was diagnosed based on characteristic valvular lesions of the mitral valve apparatus 136 (thickened and/or prolapsing mitral valve leaflets), and demonstrated mitral valve 137 regurgitation evident on color flow Doppler echocardiography.