Clinical Mechanisms of Nitrate Action

Compound salvia pellet might be more effective and safer for chronic stable angina pectoris compared with nitrates: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Chronic stable angina (CSA) resulted in a considerable burden for both individuals and the society. In this study we aimed to critically evaluate the effectiveness and safety of Compound salvia pellet compared with nitrates in the treatment of Chronic Stable Angina (CSA) pectoris, and to provide more credible evidence for clinical practice.

METHODS

A comprehensive and exhaustive search strategy was formulated to identify potential RCTs of compound salvia pellet for CSA in international and Chinese databases from their inception to July 4th, 2018. We also searched the bibliographies of relevant studies. Two reviewers independently assessed the quality of included trials by using Cochrane Risk of Bias Tool.

RESULTS

The literature search yielded 1849 citations and 51 RCTs (n = 4732) were included for meta-analysis after titles, abstracts and full text selection according to eligibility criteria. The pooled results suggested that compound salvia pellet was much more effective than nitrates in the improvement of angina symptoms (therapy = 4 weeks, RR = 1.23, 95%CI = [1.17, 1.30], P < .001, I = 0%; therapy = 4 weeks, RR = 1.13, 95%CI = [1.08, 1.17], P < .001, I = 45.6%), and ECG test (therapy = 4 weeks, RR = 1.24, 95%CI [1.14, 1.35], P < .001, I = 51.5%; and therapy > 4 weeks, RR = 1.30, 95%CI[1.20, 1.42], P < .001, I = 36.4%) in CSA. Compared with nitrates, the percentage of patients with adverse events significantly decreased when prescribed with compound salvia pellet (3.2% vs 17.0%).

CONCLUSION

Compound salvia pellet might be more effective on the improvement of angina symptoms, ECG test and with few adverse events compared with nitrates. While there are some limitations in this study, which may weaken the results, we believe the findings could provide useful information for stakeholders concerned with outcomes in patients with CSA. More rigorous RCTs with high quality are needed to confirm these findings.

Intravenous Nitroglycerin in the Treatment of Decompensated Heart Failure: Potential Benefits and Limitations

Acute decompensated heart failure (ADHF) is a common cause of hospitalizations. Intravenous nitroglycerin is widely used in the treatment of this condition. The use of this drug is based on its nitric oxide-mediated vasodilatory effect, which can lead to beneficial hemodynamic effects as well as improvement of myocardial ischemia and reduction of mitral regurgitation. However, information regarding the use of nitroglycerin for ADHF is limited to mostly hemodynamic evaluations in small groups of patients without cardiovascular outcome data. A single randomized, placebo controlled study that evaluated commonly used doses of nitroglycerin in patients with ADHF was disappointing and failed to show a significant hemodynamic effect or improvement of symptoms compared with placebo. The potential benefit of nitroglycerin seems to be limited by a decreased vasodilatory response in patients with heart failure, which requires an active titration of the drug and the use of high doses (>120 µg/min). In addition, the initial beneficial hemodynamic effect achieved with the appropriate dose of nitroglycerin is associated with neurohumoral activation and limited by an early development of nitrate tolerance that leads to a marked attenuation of the initial effect. More information obtained in large-scale studies that are appropriately designed to evaluate the effect of variable doses of nitroglycerin on short- and long-term cardiovascular outcome, with and without interventions shown to prevent nitrate tolerance, is needed before intravenous nitroglycerin can be recommended as a standard therapy for ADHF.

Additional antianginal and anti-ischemic efficacy of mibefradil in patients concomitantly treated with long-acting nitrates for chronic stable angina pectoris

BACKGROUND

Mibefradil, a newly approved antihypertensive and antianginal drug, is the first member of a new class of calcium antagonists (CAs), the tetralol derivatives, that selectively blocks T-type Ca2+ channels in contrast to classical CAs which, at therapeutic concentrations, block only L-type Ca2+ channels. Since patients with chronic stable angina pectoris typically may be treated with the combination of a long-acting nitrate and a CA, the additive efficacy and safety of mibefradil in combination with nitrate therapy needs to be determined.

HYPOTHESIS

This study was designed to assess the efficacy, tolerability, and safety of mibefradil when added to long-acting nitrate therapy in patients with chronic stable angina pectoris.

METHODS

Following a 1-week placebo run-in period, patients were randomized to receive either mibefradil 50 mg (n = 96) or placebo (n = 93) once daily in addition to their nitrate therapy. After 2 weeks of active treatment, patients receiving the mibefradil were force titrated to 150 mg once daily for an additional 2 weeks. Exercise tolerance tests (ETTs) were performed at the end of Weeks 2 and 4; patients also maintained an anginal diary during the 4-week treatment period.

RESULTS

After 2 weeks of treatment with 50 mg mibefradil (within the current recommended dose range), a statistically significant but modest increase in total exercise duration was observed (treatment effect 16.4 s, p = 0.04). Similarly, there was a significant increase in time to onset of ischemia (treatment effect 26 s, p = 0.008). The adverse event profile of the 50 mg dose was indistinguishable from placebo, indicating that this dose was extremely well tolerated. At Week 4, the mibefradil-treated patients were taking 150 mg, which is above the current recommended dose range. The increase in total exercise duration was larger for the mibefradil 150 mg group than for the placebo group. For the intent-to-treat population, this difference did not reach statistical significance, whereas in the standard population it did (treatment effect 21 s, p = 0.05). The other two ETT variables, time to onset of angina and time to onset of 1 mm ST-segment depression, demonstrated significantly greater effect with mibefradil 150 mg (treatment effects 40 s, p = 0.002, and 55 s, p < 0.001, respectively, for the intent-to-treat population). Mibefradil 150 mg was associated with more adverse events than placebo, specifically, dizziness, leg edema, and postural hypotension.

CONCLUSIONS

This study demonstrates that mibefradil 50 mg once daily in the setting of the background long-acting nitrate therapy produces additive antianginal and anti-ischemic effects and is extremely well tolerated.

Survey of the use of organic nitrates for the treatment of chronic congestive heart failure in the United States

A survey of members of the Heart Failure Society of America revealed that despite their lack of approval by the United States Food and Drug Administration, nitrates are widely used in patients with chronic congestive heart failure (CHF). Most members reported using nitrates in patients with ischemic (90%) and nonischemic (81%) causes of chronic CHF, especially those with symptomatic CHF (43% reported using nitrates in >50% of their patients with ischemic and 25% with nonischemic causes). Ninety-six percent reported using nitrates to reduce symptoms, 74% for hemodynamic improvement, 65% for better exercise tolerance, and only 14% for left ventricular reversed remodeling. Nitrates were always combined with hydralazine in 25% of patients and occasionally combined with hydralazine in 67%.

Double-blind, placebo-controlled study to evaluate the effect of organic nitrates in patients with chronic heart failure treated with angiotensin-converting enzyme inhibition

BACKGROUND

Organic nitrates are widely used in the treatment of chronic heart failure (CHF). No information, however, is available regarding their effect in patients already treated with ACE inhibitors.

METHODS AND RESULTS

In a randomized, double-blind, crossover design, we studied the effects of high-dose (50 to 100 mg) transdermal nitroglycerin (NTG) and placebo given daily for 12 hours in 29 patients with CHF (NYHA functional classes II to III). Exercise time (4 hours after patch application) showed a progressive improvement during NTG administration, with an increase of 38+/-35 seconds (9+/-7%) at the end of the first month (P=NS), 76+/-28 seconds (16+/-6%) at the end of the second month (P=0.01), and 117+/-34 seconds (27+/-6%) at the end of the third month (P=0.003). No significant change was seen during placebo administration (12+/-20, 5+/-26, and 19+/-28 seconds, all P=NS). Exercise time 8 hours after NTG application measured at 3 months was also significantly longer, with a difference of 87+/-28 seconds (P=0.006), but not with placebo (23+/-36 seconds, P=0.53). Assessment of quality of life and need for additional diuretics or hospitalizations for CHF failed to demonstrate a significant difference between the 2 treatment periods. In contrast, NTG decreased left ventricular end-diastolic (-2.1+/-0.1%, P<0.05) and end-systolic (-3.2+/-1.3%, P<0.05) dimensions and augmented LV fractional shortening (24.7+/-10.5%, P<0.03). The effect of placebo on these parameters was not statistically significant.

CONCLUSION

High-dose nitrate therapy significantly improves exercise tolerance and left ventricular size and systolic function in patients with chronic, mild to moderate CHF already treated with ACE inhibitors. These findings support the role of organic nitrates as an adjunctive therapy to ACE inhibitors in patients with chronic CHF.

The role of organic nitrates in the treatment of heart failure

Nitrates have been widely used in the treatment of patients with chronic congestive heart failure. Although the use of these drugs has not been approved by the Food and Drug Administration, multiple studies have shown their favorable effects. Organic nitrates have been shown to have a beneficial effect on ischemia, hemodynamic profile, magnitude of a mitral regurgitation, endothelial function, and cardiac remodeling. These drugs, when used in combination with hydralazine, have improved exercise capacity and survival. Recent studies have shown that the use of nitrates in patients already treated with standard heart failure therapy, including angiotensin converting enzyme (ACE) inhibitors, resulted in hemodynamic improvement, marked enhancement of exercise tolerance, reduction of left ventricular size, and augmentation of systolic function. These data suggest a role for organic nitrates as an adjunctive therapy to ACE inhibitors in patients with chronic heart failure and for nitrates in combination with hydralazine as an alternative treatment in patients who are intolerant to ACE inhibitors.