Nitrates in acute myocardial infarction.

Area of Science:

• Cardiology
• Pharmacology
• Emergency Medicine

Background:

• Acute myocardial infarction (AMI) involves myocardial ischaemia, leading to impaired left ventricular function.
• Nitrates are vasodilators used to manage cardiovascular conditions.

Purpose of the Study:

• To review the effects of nitrates, particularly glyceryl trinitrate, on haemodynamics and infarct evolution in acute myocardial infarction.
• To assess the benefits and risks of nitrate administration in AMI patients.

Main Methods:

• Review of existing human and animal studies on nitrate administration in AMI.
• Analysis of glyceryl trinitrate's effects on myocardial oxygen consumption, coronary flow, and haemodynamics.
• Examination of dose-dependency and potential adverse effects like hypotension.

Main Results:

• Nitrates improve left ventricular haemodynamics and reduce infarct evolution when administered early (within 6 hours).
• Glyceryl trinitrate enhances myocardial oxygen supply/demand balance and improves collateral flow.
• Hypotension is a significant side effect (15-20%), particularly in hypovolaemic patients or those with right heart infarction.

Conclusions:

• Early nitrate administration in AMI offers significant benefits, especially for patients with left ventricular dysfunction.
• Optimal nitrate dosing is critical; excessive doses (>100 mcg/min) can worsen ischaemia.
• Further randomized controlled trials are needed to definitively establish nitrate's role in reducing AMI morbidity and mortality.