From the Guidelines
Nitrates should be avoided in patients with aortic stenosis because they can cause dangerous hypotension that may lead to cardiovascular collapse. In aortic stenosis, the narrowed aortic valve creates a fixed obstruction to blood flow from the left ventricle into the systemic circulation. These patients are preload-dependent, meaning they rely on adequate venous return to maintain cardiac output. Nitrates like nitroglycerin cause venodilation, reducing preload (blood returning to the heart), which decreases left ventricular filling pressures. In aortic stenosis, this reduction in preload can't be compensated for due to the fixed outflow obstruction, resulting in decreased cardiac output, hypotension, and potentially syncope or shock. Additionally, the coronary perfusion in these patients is already compromised due to increased left ventricular pressure and myocardial hypertrophy, and nitrate-induced hypotension can further reduce coronary blood flow, potentially causing myocardial ischemia.
According to the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1, careful use of antihypertensive agents to achieve BP control in patients with hypertension and aortic stenosis is beneficial. However, nitroglycerin should be used with caution in patients with aortic stenosis, as it can cause hypotension and reduce coronary perfusion. The guideline also suggests that RAS blockade may be advantageous in patients with aortic stenosis due to its potentially beneficial effects on LV fibrosis, control of hypertension, reduction of dyspnea, and improved effort tolerance.
Some key points to consider when managing patients with aortic stenosis include:
- Avoiding nitrates due to the risk of hypotension and reduced coronary perfusion
- Using antihypertensive agents with caution to achieve BP control
- Considering RAS blockade as a potentially beneficial treatment option
- Monitoring patients closely for signs of hypotension, reduced coronary perfusion, and other complications.
It's also important to note that the use of nitrates in patients with aortic stenosis is not supported by strong evidence, and the potential benefits of nitrate therapy in these patients are unclear 1. Therefore, the use of nitrates in patients with aortic stenosis should be approached with caution and careful consideration of the potential risks and benefits.
From the Research
Rationale for Not Giving Nitro in Aortic Stenosis
- The primary concern with administering nitrates, such as nitroglycerin, in patients with aortic stenosis is the potential for precipitating profound hypotension 2.
- Aortic stenosis is characterized by a narrowing of the aortic valve, which can lead to a fixed cardiac output and increased reliance on preload to maintain cardiac output.
- Nitrates can cause vasodilation, which can lead to a decrease in preload and potentially worsen cardiac output in patients with aortic stenosis.
- However, a study published in the Annals of Emergency Medicine found that neither moderate nor severe aortic stenosis was associated with a greater risk of clinically relevant hypotension requiring intervention when nitroglycerin was used for acute pulmonary edema 2.
Alternative Treatment Options
- Antihypertensive treatment in severe aortic stenosis was previously considered a relative contraindication, but recent studies have shown that it may be safe and even beneficial in reducing the progression of left ventricular pressure overload and retarding the progression of valvular aortic stenosis 3.
- Beta-blockers have generally been avoided in patients with severe aortic stenosis due to concerns about inducing left ventricular dysfunction and hemodynamic compromise, but recent studies have shown that they may be safe and even beneficial 3.
- Renin-angiotensin system (RAS) inhibitors may be beneficial in patients with aortic stenosis, as they can help to reduce left ventricular pressure overload and retard the progression of valvular stenosis 3, 4.
Clinical Considerations
- Patients with aortic stenosis should be educated about the importance of promptly reporting symptoms to their physicians, and serial Doppler echocardiography is recommended every 6-12 months for severe aortic stenosis, every 1-2 years for moderate disease, and every 3-5 years for mild disease 5.
- Medical management of concurrent hypertension, atrial fibrillation, and coronary artery disease is crucial to achieve optimal outcomes in patients with aortic stenosis 5, 4.
- Calcium channel blockers may be associated with lower survival in patients with aortic stenosis, and diuretics may have disadvantages in patients with left ventricular hypertrophy and smaller left ventricular cavity dimensions 4, 6.