Tolerance to intravenous nitroglycerin in patients with congestive heart failure: role of increased intravascular volume, neurohumoral activation and lack of prevention with N-acetylcysteine

Nicardipine versus nitroglycerin for hypertensive acute heart failure syndrome: a single-center observational study

Objective: Nitroglycerin is a first-line treatment for hypertensive acute heart failure syndrome (AHFS). However, nicardipine is frequently used to treat hypertensive emergencies, including AHFS. In this study, we compared the effectiveness of nicardipine and nitroglycerin in patients with hypertensive AHFS.

Patients and Methods: This single-center, retrospective, observational study was conducted at the intensive care unit of a Japanese hospital. Patients diagnosed with AHFS and systolic blood pressure 140 mmHg on arrival between April 2013 and March 2021 were included. The outcomes were the time to optimal blood pressure control, duration of continuous infusion of antihypertensive agents, duration of positive pressure ventilation, need for additional antihypertensive agents, length of hospital stay, and body weight changes. Outcomes were compared between the nicardipine and nitroglycerin groups. We also compared these outcomes between the groups after excluding patients who received renal replacement therapy.

Results: Fifty-eight patients were enrolled (26 and 32 patients were treated with nitroglycerin and nicardipine, respectively). The nicardipine group had a shorter time to optimal blood pressure control (2.0 [interquartile range, 2.0–8.5] h vs. 1.0 [0.5–2.0] h), shorter duration of continuous anti-hypertensive agent infusion (3.0 [2.0–5.0] days vs. 2.0 [1.0–2.0] days), less frequent need for additional anti-hypertensive agents (1 patients [3.1%] vs. 11 patients [42.3%]), and shorter length of hospital stay (17.5 [10.0–33.0] days vs. 9.0 [5.0–15.0] days) than the nitroglycerin group. The duration of positive pressure ventilation and body weight changes were similar between the groups. The outcomes were similar after excluding patients who received renal replacement therapy.

Conclusion: Nicardipine may be more effective than nitroglycerin for treating hypertensive AHFS.

Hemoglobin and Clinical Outcomes in the Vericiguat Global Study in Patients With Heart Failure and Reduced Ejection Fraction (VICTORIA)

BACKGROUND

In the VICTORIA trial (Vericiguat Global Study in Patients with Heart Failure with Reduced Ejection Fraction), anemia occurred more often in patients treated with vericiguat (7.6%) than with placebo (5.7%). We explored the association between vericiguat, randomization hemoglobin, development of anemia, and whether the benefit of vericiguat related to baseline hemoglobin.

METHODS

Anemia was defined as hemoglobin <13.0 g/dL in men and <12.0 g/dL in women (World Health Organization Anemia). Adverse events reported as anemia were also evaluated. We assessed the risk-adjusted relationship between hemoglobin and hematocrit with the primary outcome (composite of cardiovascular death or heart failure hospitalization) and the time-updated hemoglobin relationship to outcomes.

RESULTS

At baseline, 1719 (35.7%) patients had World Health Organization anemia; median hemoglobin was 13.4 g/L (25th, 75th percentile: 12.1, 14.7 g/dL). At 16 weeks from randomization, 1643 patients had World Health Organization anemia (284 new for vericiguat and 219 for placebo), which occurred more often with vericiguat than placebo (P<0.001). After 16 weeks, no further decline in hemoglobin occurred over 96 weeks of follow-up and the ratio of hemoglobin/hematocrit remained constant. Overall, adverse event anemia occurred in 342 patients (7.1%). A lower hemoglobin was unrelated to the treatment benefit of vericiguat (versus placebo) on the primary outcome. In addition, analysis of time-updated hemoglobin revealed no association with the treatment effect of vericiguat (versus placebo) on the primary outcome.

CONCLUSIONS

Anemia was common at randomization and lower hemoglobin was associated with a greater frequency of clinical events. Although vericiguat modestly lowered hemoglobin by 16 weeks, this effect did not further progress nor was it related to the treatment benefit of vericiguat. Registration: URL: https://www.clinicaltrials.gov: Unique identifier: NCT02861534.

Acute effects of sublingual nitroglycerin on cardiovagal and sympathetic baroreflex sensitivity

The effects of nitroglycerin (glyceryl trinitrate, GTN) on baroreflex sensitivity (BRS) are incompletely understood. Moreover, there are no reports evaluating the acute responses in both the sympathetic BRS (SBRS) and the cardiovagal BRS (CBRS) to the administration of sublingual GTN. We hypothesized that sublingual GTN modulates both CBRS and SBRS. In 10 healthy subjects, beat-to-beat heart rate (HR), blood pressure (BP) and muscle sympathetic nerve activity (MSNA) were recorded before and for 10 min after sublingual administration of GTN 0.4 mg. SBRS was evaluated from the relationship between spontaneous variations in diastolic BP and MSNA. CBRS was assessed with the sequence technique. These variables were assessed during baseline, during min 3^rd - 6^th (Post A) and 7^th -10^th min (Post B) after GTN administration. Two min after GTN administration, MSNA increased significantly and remained significantly elevated during recording. Compared to baseline, CBRS decreased significantly (Post A: 12.9 ± 1.6 to 7.1 ± 1.0 ms/mmHg, P < 0.05), while SBRS increased significantly (Post A: 0.8 ± 0.2 to 1.5 ± 0.2 units･beat^-1･mmHg^-1, P < 0.05) with an upward shift of the operating point. There were no differences in these variables between Post A and B. A clinical dose of GTN increased MSNA rapidly through effects on both CBRS and SBRS. These effects should be kept in mind when nitrates are used to clinically treat chest pain and acute coronary syndromes and used as vasodilators in experimental settings.

KSHF Guidelines for the Management of Acute Heart Failure: Part II. Treatment of Acute Heart Failure

The prevalence of heart failure (HF) is on the rise due to the aging of society. Furthermore, the continuous progress and widespread adoption of screening and diagnostic strategies have led to an increase in the detection rate of HF, effectively increasing the number of patients requiring monitoring and treatment. Because HF is associated with substantial rates of mortality and morbidity, as well as high socioeconomic burden, there is an increasing need for developing specific guidelines for HF management. The Korean guidelines for the diagnosis and management of chronic HF were introduced in March 2016. However, chronic and acute HF represent distinct disease entities. Here, we introduce the Korean guidelines for the management of acute HF with reduced or preserved ejection fraction. Part II of this guideline covers the treatment of acute HF.

The Role of Nitroglycerin and Other Nitrogen Oxides in Cardiovascular Therapeutics

The use of nitroglycerin in the treatment of angina pectoris began not long after its original synthesis in 1847. Since then, the discovery of nitric oxide as a biological effector and better understanding of its roles in vasodilation, cell permeability, platelet function, inflammation, and other vascular processes have advanced our knowledge of the hemodynamic (mostly mediated through vasodilation of capacitance and conductance arteries) and nonhemodynamic effects of organic nitrate therapy, via both nitric oxide-dependent and -independent mechanisms. Nitrates are rapidly absorbed from mucous membranes, the gastrointestinal tract, and the skin; thus, nitroglycerin is available in a number of preparations for delivery via several routes: oral tablets, sublingual tablets, buccal tablets, sublingual spray, transdermal ointment, and transdermal patch, as well as intravenous formulations. Organic nitrates are commonly used in the treatment of cardiovascular disease, but clinical data limit their use mostly to the treatment of angina. They are also used in the treatment of subsets of patients with heart failure and pulmonary hypertension. One major limitation of the use of nitrates is the development of tolerance. Although several agents have been studied for use in the prevention of nitrate tolerance, none are currently recommended owing to a paucity of supportive clinical data. Only 1 method of preventing nitrate tolerance remains widely accepted: the use of a dosing strategy that provides an interval of no or low nitrate exposure during each 24-h period. Nitric oxide's important role in several cardiovascular disease mechanisms continues to drive research toward finding novel ways to affect both endogenous and exogenous sources of this key molecular mediator.

Soluble Guanylate Cyclase Stimulators and Activators: Novel Therapies for Pulmonary Vascular Disease or a Different Method of Increasing cGMP?

Pulmonary arterial hypertension (PAH) is a progressively worsening disorder characterized by increased pulmonary vascular resistance leading to increased afterload, right ventricular hypertrophy, and ultimately right heart failure and death. Current pharmacologic treatments primarily act to reduce pulmonary vascular resistance (PVR) and provide some benefit but do not cure PAH. Canonical vasodilator therapy involving the nitric oxide (NO)-soluble guanylate cyclase (sGC)-cGMP pathway has demonstrated efficacy, but in pathologic states, endothelial dysfunction within the pulmonary vasculature leads to the reduced synthesis and bioavailability of NO. Acting downstream of NO, sGC stimulators and activators restore the endogenous functions of NO and exploit the positive effects of sGC stimulation on various organ systems, including the heart. Riociguat (BAY 63-2521) is the first agent in a class of sGC stimulators to receive FDA approval for the treatment of PAH and chronic thromboembolic hypertension (CTEPH). Riociguat has demonstrated significant benefit as assessed by 6MWD, PVR, N-terminal pro-brain natriuretic peptide (NT-proBNP) levels, time to clinical worsening, World Health Organization (WHO) functional class, and other quality of life measures in clinical trials as a monotherapy and in combination with endothelin receptor antagonists or non-intravenous prostanoids. Riociguat is the first FDA-approved treatment option for inoperable or persistent CTEPH and adds a new effective drug to available treatment options for pulmonary hypertension (PH). The question of whether riociguat is superior to other available treatment options is unanswered at the present time and requires further study.

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.

Nitrates as a Treatment of Acute Heart Failure

The purpose of this article is to review the clinical efficacy and safety of nitrates in acute heart failure (AHF) by examining various trials on nitrates in AHF. Management of AHF can be challenging due to the lack of objective clinical evidence guiding optimal management. There have been many articles suggesting that, despite a benefit, nitrates are underused in clinical practice. Nitrates, when appropriately dosed, have a favourable effect on symptoms, blood pressure, intubation rates, mortality and other parameters.

Challenges with nitrate therapy and nitrate tolerance: prevalence, prevention, and clinical relevance

Nitrate therapy has been an effective treatment for ischemic heart disease for over 100 years. The anti-ischemic and exercise-promoting benefits of sublingually administered nitrates are well established. Nitroglycerin is indicated for the relief of an established attack of angina and for prophylactic use, but its effects are short lived. In an effort to increase the duration of beneficial effects, long-acting orally administered and topical applications of nitrates have been developed; however, following their continued or frequent daily use, patients soon develop tolerance to these long-acting nitrate preparations. Once tolerance develops, patients begin losing the protective effects of the long-acting nitrate therapy. By providing a nitrate-free interval, or declining nitrate levels at night, one can overcome or reduce the development of tolerance, but cannot provide 24-h anti-anginal and anti-ischemic protection. In addition, patients may be vulnerable to occurrence of rebound angina and myocardial ischemia during periods of absent nitrate levels at night and early hours of the morning, and worsening of exercise capacity prior to the morning dose of the medication. This has been a concern with nitroglycerin patches but not with oral formulations of isosorbide-5 mononitrates, and has not been adequately studied with isosorbide dinitrate. This paper describes problems associated with nitrate tolerance, reviews mechanisms by which nitrate tolerance and loss of efficacy develop, and presents strategies to avoid nitrate tolerance and maintain efficacy when using long-acting nitrate formulations.