A standard treatment for heart attack patients, nitroglycerin is typically prescribed to aid in opening vessels so blood can flow to the heart more easily. A typical regimen is for hospitalized heart attack patients to be cycled on and off the nitroglycerin, 16 hours on and 8 hours off, to reduce desensitization to the drug.
But a Stanford study published today in Science Translational Medicine shows that prolonged use of the heart medication may actually increase the severity of subsequent heart attacks - and serves as a cautionary tale to cardiologists. In the study, researchers tested the effect of sustained nitroglycerin treatment on the severity of heart attacks using a rat model. As described in our release:
They found that nitroglycerin increased heart attack severity in rats. After 16 hours of nitroglycerin treatment, the heart damage was twice as large as in untreated control animals. Five to eight animals made up each group.
Cardiac function was also significantly diminished in relation to the control animals, as determined by echocardiograms immediately after the heart attack and again two weeks later. And when the rats were given the enzyme activator Alda-1 along with nitroglycerin, the detrimental effects of prolonged nitroglycerin treatment were nearly erased.
John Cooke, MD, PhD, a Stanford professor of cardiovascular medicine who was not involved in the study but has discussed it with the researchers, also provided comment in the release:
Continuous administration of nitroglycerin by patch or by intravenous infusion, as in the coronary care unit, is initially useful in relieving pain and also favorably influences hemodynamics — reduces blood pressure, improves coronary blood flow. However, extended use of this form of nitroglycerin is known to induce tolerance to its own beneficial actions within 12 to 24 hours.
[This study] raises additional concern about the extended use of long-acting or continuous administration of nitroglycerin in the coronary care unit. It is probably best to use nitroglycerin continuously for only short periods of time, and replace the continuous infusion or patch with other medications to reduce symptoms and favorably influence hemodynamics.
Previously: Why some healthy-looking young adults may still be at risk for heart disease, Researchers identify more heart attack genes, Study disproves link between gene variant and coronary-disease risk and Wider statin use may be cost-effective way to prevent heart attack, stroke