Angiotensin Receptor Blockers: Novel Role in High-Risk Patients

Efficacy of Ace Inhibition with Zofenopril, Lisinopril, or Ramipril in Postacute Myocardial Infarction Patients With or Without Metabolic Syndrome: A Pooled Individual Data Analysis of Four Randomized, Double-Blind, Controlled, Prospective Studies

Background: The metabolic syndrome (MS) is a clustering of different cardiovascular (CV) risk factors, which further enhances the risk of death and CV complications in post-acute myocardial infarction (AMI) patients. In the present meta-analysis of individual data of the four randomized, prospective SMILE studies, we evaluated the efficacy of zofenopril vs. lisinopril, ramipril, and placebo on 1-year CV morbidity and mortality, according to the presence (+) or absence (−) of the MS.

Methods: 2203 (63.2%) of the 3488 patients were classified as MS+, 1285 (36.8%) as MS−. Five hundred two MS+ and 380 MS− were treated with placebo, 1134 and 608 with zofenopril 30–60 mg/die, 340 and 175 with lisinopril 5–10 mg/die, and 227 and 122 with ramipril 10 mg/die. Treatment was continued for 6 to 48 weeks.

Results: The 1-year risk of a major CV event was similar (P = 0.420) in MS+ (18.1%) and MS− (18.0%) patients [HR and 95% confidence interval: 0.92 (0.76–1.12)]. After accounting for MS+/MS−, the 1-year risk of CV events vs. placebo was significantly lower under zofenopril [0.79 (0.63–0.97); P = 0.028] and lisinopril [0.65 (0.47–0.89); P = 0.007], but larger under ramipril [2.57 (1.94–3.93); P = 0.0001]. Treatment with zofenopril was associated with a statistically significant (P = 0.0001) reduction in CV risk as compared with the other angiotensin-converting enzyme inhibitors [MS+: 0.52 (0.42–0.66); MS−: 0.52 (0.38–0.73)].

Conclusions: In post-AMI patients with MS, zofenopril treatment is associated with a clinically relevant reduction in long-term CV morbidity and mortality, compared with placebo, with an efficacy similar to lisinopril, but better than ramipril.

Divergent Roles of Matrix Metalloproteinase 2 in Pathogenesis of Thoracic Aortic Aneurysm

Objective—

Aortic aneurysm, focal dilation of the aorta, results from impaired integrity of aortic extracellular matrix (ECM). Matrix metalloproteinases (MMPs) are traditionally known as ECM-degrading enzymes. MMP2 has been associated with aneurysm in patients and in animal models. We investigated the role of MMP2 in thoracic aortic aneurysm using 2 models of aortic remodeling and aneurysm.

Approach and Results—

Male 10-week-old MMP2-deficient (MMP2 −/− ) and wild-type mice received angiotensin II (Ang II, 1.5 mg/kg/day) or saline (Alzet pump) for 4 weeks. Although both genotypes exhibited dilation of the ascending aorta after Ang II infusion, MMP2 −/− mice showed more severe dilation of the thoracic aorta and thoracic aortic aneurysm. The Ang II–induced increase in elastin and collagen (mRNA and protein) was markedly suppressed in MMP2 −/− thoracic aorta and smooth muscle cells, whereas only mRNA levels were reduced in MMP2 −/− -Ang II abdominal aorta. Consistent with the absence of MMP2, proteolytic activities were lower in MMP2 −/− -Ang II compared with wild-type-Ang II thoracic and abdominal aorta. MMP2-deficiency suppressed the activation of latent transforming growth factor-β and the Smad2/3 pathway in vivo and in vitro. Intriguingly, MMP2 −/− mice were protected against CaCl 2 -induced thoracic aortic aneurysm, which triggered ECM degradation but not synthesis.

Conclusions—

This study reveals the dual role of MMP2 in ECM degradation, as well as ECM synthesis. Moreover, the greater susceptibility of the thoracic aorta to impaired ECM synthesis, compared with vulnerability of the abdominal aorta to aberrant ECM degradation, provides an insight into the regional susceptibility of the aorta to aneurysm development.

Antihypertensive efficacy and safety of olmesartan medoxomil and ramipril in elderly mild to moderate essential hypertensive patients with or without metabolic syndrome: a pooled post hoc analysis of two comparative trials

BACKGROUND

Two recent identically designed trials (one Italian and one European multinational) have compared the head-to-head efficacy and safety of the angiotensin II receptor blocker olmesartan medoxomil and the angiotensin converting enzyme inhibitor ramipril, in elderly patients with essential hypertension.

OBJECTIVE

The aim of the present study was to assess the antihypertensive efficacy of olmesartan and ramipril in elderly patients with hypertension, with or without metabolic syndrome, by performing a pooled analysis of data from the two head-to-head trials.

METHODS

After a 2-week, placebo wash-out, 1,453 treated or untreated elderly hypertensive patients aged 65-89 years [with sitting office diastolic blood pressure (DBP) 90-109 mmHg and/or sitting office systolic BP (SBP) 140-179 mmHg] were randomized to 12-weeks of double-blind treatment with olmesartan 10 mg or ramipril 2.5 mg once daily. Treatment could be up-titrated to 20 and 40 mg for olmesartan, and 5 and 10 mg for ramipril, after the first 2 and 6 weeks, respectively, in patients with inadequately controlled BP (BP ≥ 140/90 mmHg for non-diabetics and ≥ 130/80 mmHg for diabetics). Office BP was measured at randomization and after 2, 6 and 12 weeks of treatment. 24-h ambulatory BP recordings were obtained at randomization and after 12 weeks.

RESULTS

Of the 1,426 patients in the intent-to-treat analysis, 735 (51.5 %) had metabolic syndrome (olmesartan, n = 372; ramipril, n = 363). After 12 weeks of treatment, baseline-adjusted office BP reductions were greater (p < 0.05) with olmesartan (SBP 17.0 mmHg; 95% CI 18.4, 15.6; DBP 9.6 mmHg; 95% CI 10.4, 8.8) than with ramipril (SBP 14.7 mmHg; 95% CI 16.1, 13.2; DBP 8.4 mmHg; 95% CI 9.2, 7.6) in patients with metabolic syndrome. In these patients, BP normalization rates were also greater with olmesartan than with ramipril (46.0 vs. 35.8%, p < 0.01). Similarly, in patients without metabolic syndrome, the antihypertensive efficacy of olmesartan was also significantly (p < 0.05) better than that of ramipril. In the subgroup of patients with valid ambulatory BP (ABP) recordings and metabolic syndrome (olmesartan, n = 182; ramipril, n = 170), the reduction in mean 24-h ABP was greater with olmesartan (SBP 10.2 mmHg; 95% CI 11.8, 8.6; DBP 6.6 mmHg; 95% CI 7.5, 5.6) than with ramipril (SBP 8.5 mmHg; 95% CI 10.2, 6.9; DBP 4.7 mmHg; 95% CI 5.7, 3.7), with a statistically significant (p < 0.01) difference for the DBP comparison. The proportion of patients experiencing drug-related adverse events was comparable in patients with (olmesartan 2.4 % vs. ramipril 2.8 %) and without (3.5 vs. 3.7 %) metabolic syndrome.

CONCLUSIONS

Olmesartan provides more effective BP control than ramipril in elderly hypertensive patients with and without metabolic syndrome.

Loss of Timp3 gene leads to abdominal aortic aneurysm formation in response to angiotensin II

Aortic aneurysm is dilation of the aorta primarily due to degradation of the aortic wall extracellular matrix (ECM). Tissue inhibitors of metalloproteinases (TIMPs) inhibit matrix metalloproteinases (MMPs), the proteases that degrade the ECM. Timp3 is the only ECM-bound Timp, and its levels are altered in the aorta from patients with abdominal aortic aneurysm (AAA). We investigated the causal role of Timp3 in AAA formation. Infusion of angiotensin II (Ang II) using micro-osmotic (Alzet) pumps in Timp3(-/-) male mice, but not in wild type control mice, led to adverse remodeling of the abdominal aorta, reduced collagen and elastin proteins but not mRNA, and elevated proteolytic activities, suggesting excess protein degradation within 2 weeks that led to formation of AAA by 4 weeks. Intriguingly, despite early up-regulation of MMP2 in Timp3(-/-)Ang II aortas, additional deletion of Mmp2 in these mice (Timp3(-/-)/Mmp2(-/-)) resulted in exacerbated AAA, compromised survival due to aortic rupture, and inflammation in the abdominal aorta. Reconstitution of WT bone marrow in Timp3(-/-)/Mmp2(-/-) mice reduced inflammation and prevented AAA in these animals following Ang II infusion. Treatment with a broad spectrum MMP inhibitor (PD166793) prevented the Ang II-induced AAA in Timp3(-/-) and Timp3(-/-)/Mmp2(-/-) mice. Our study demonstrates that the regulatory function of TIMP3 is critical in preventing adverse vascular remodeling and AAA. Hence, replenishing TIMP3, a physiological inhibitor of a number of metalloproteinases, could serve as a therapeutic approach in limiting AAA development or expansion.