From the Guidelines
Hydralazine is contraindicated in patients with a history of coronary artery disease (CAD) due to its potential to cause reflex tachycardia and increased myocardial oxygen demand, which can worsen cardiac ischemia or precipitate angina attacks in these vulnerable patients. When hydralazine dilates peripheral blood vessels, it reduces peripheral vascular resistance and blood pressure. This drop in blood pressure triggers compensatory mechanisms, including activation of the sympathetic nervous system and the renin-angiotensin-aldosterone system, leading to increased heart rate and cardiac output. For CAD patients with already compromised coronary blood flow, this increased cardiac workload can be dangerous as their diseased coronary arteries cannot meet the heightened oxygen demands of the heart muscle. Additionally, the reduced diastolic blood pressure that occurs with hydralazine can further decrease coronary perfusion, exacerbating myocardial ischemia. If blood pressure reduction is necessary in CAD patients, alternative antihypertensives such as beta-blockers, calcium channel blockers, or ACE inhibitors are generally preferred as they don't produce the same degree of reflex tachycardia and may offer cardioprotective benefits 1. Some key points to consider when managing hypertension in patients with CAD include:
- The use of beta-blockers, ACE inhibitors, and calcium channel blockers as first-line agents for hypertension in CAD patients 1.
- The importance of careful monitoring and individualized treatment plans to minimize the risk of adverse effects and optimize outcomes 1.
- The need to consider the patient's overall clinical profile, including the presence of comorbidities and the potential for drug interactions, when selecting an antihypertensive agent 1.
From the FDA Drug Label
Contraindications Hypersensitivity to hydralazine; coronary artery disease; mitral valvular rheumatic heart disease. Precautions General: Myocardial stimulation produced by hydralazine can cause anginal attacks and ECG changes of myocardial ischemia. The drug has been implicated in the production of myocardial infarction. It must, therefore, be used with caution in patients with suspected coronary artery disease
Hydralazine is contraindicated in patients with a history of Coronary Artery Disease (CAD) because it can cause myocardial stimulation, leading to anginal attacks and ECG changes of myocardial ischemia, and has been implicated in the production of myocardial infarction 2 2.
From the Research
Hydralazine Contraindication in CAD
- Hydralazine is contraindicated in patients with a history of Coronary Artery Disease (CAD) due to its potential to provoke myocardial ischemic events 3.
- The mechanism underlying this contraindication is thought to be related to the relative preservation of elevated left ventricular preload with hydralazine, which can lead to ischemic events 3.
- Reflex tachycardia is another potential mechanism by which hydralazine can provoke myocardial ischemic events in patients with CAD 4.
- Studies have shown that hydralazine can increase cardiac output and reduce systemic vascular resistance, but it may not be beneficial for patients with CAD due to its potential to cause ischemic events 5.
- Other treatments, such as ranolazine, have been shown to be effective in reducing angina frequency and improving exercise duration in patients with stable CAD, without substantially affecting blood pressure and heart rate 6.
- In some cases, alternative therapies like prazosin may be used to achieve hemodynamic benefit and symptomatic improvement in patients with heart failure and CAD who experience adverse effects with hydralazine 7.