Coronary Circulation Diseases, Classic Angina, and Myocardial Infarction: Assessment, Analysis, and Associated Dental Management Guidelines
Angina and myocardial infarction (MI) can occur with involvement of the coronary circulation. Hypertension causes narrowing of the coronary arteries, and when the patient is involved in an activity, these narrowed arteries are unable to supply adequate nutrition and oxygenation to the heart, thus leading to angina. Hypertension-associated angina is classic angina and it can be stable or unstable.
PREVENTION AND TREATMENT OF ANGINA
Stable angina is always brought on by activity; it happens infrequently and it is always controlled immediately with 1–3 nitroglycerine (NTG) pills. Patients with stable angina have a good prognosis but the patient can deteriorate progressively in proportion to the severity of symptoms. The most recent evidence-based clinical guidelines on the management of stable angina are detailed in the following sections.
Angina Treatment and Prevention: Short-Acting Drugs
Glyceryl trinitrate/nitroglycerine and nifedipine capsules can be used to treat or prevent episodes of angina. Sublingual glyceryl trinitrate relieves episodes of angina more effectively than sublingual nifedipine. Glyceryl trinitrate spray is easy to use and can be stored over long periods without loss of effectiveness. Glyceryl trinitrate tablets lose efficacy after exposure to air and should be discarded after eight weeks of use. Short-acting nitrates should also be used for prophylaxis before planned exercise or exertion.
Optimal Prevention Treatments
Per new evidence-based guidelines, all patients with stable angina should get optimal medical treatment for angina prevention with one or two anti-anginal drugs, in addition to drugs for secondary prevention of cardiovascular disease.
First-Line Anti-Anginal Drugs
β Blockers and Calcium Channel Blockers
- These anti-anginal drugs prevent angina by decreasing myocardial oxygen demand by lowering heart rate, blood pressure, myocardial contractility, and/or by increasing myocardial oxygen supply through increased coronary blood flow. Monotherapy with a β blocker or with a calcium channel blocker is effective in the treatment of stable angina, but a β blocker is the preferred first-line treatment.
- β blocker members include propanolol, atenolol, and metoprolol. Calcium channel blocker members include nifedipine, diltiazem, and verapamil. The choice of drug used is determined by comorbidities, contraindications, and patient preference. If the first drug is not tolerated or does not control the symptoms, the patient is switched to the other drug class, or combination therapy with both drug classes is offered. A dihydropyridine calcium channel blocker is used when a calcium channel blocker is combined with a β blocker.
Additional Anti-Anginal Drugs
Long-acting organic nitrates are used widely in the treatment of patients with stable angina. Isosorbide mononitrate (Imdur) or felodipine (Plendil) is added to a β blocker and is effective short-term. Long-term nitrate use is limited due to the development of tolerance.
Ivabradine lowers the heart rate by selectively inhibiting the If ion current, which is significantly expressed in the sinoatrial node. Short-term trials of ivabradine versus atenolol or amlodipine in patients with stable angina demonstrated similar increases in exercise time and reductions in angina frequency.
Nicorandil is a nitrate derivative of nicotinamide that dilates epicardial and systemic venous capacitance vessels, but it also opens ATP-sensitive potassium channels in vascular smooth muscle cells, thereby dilating arterial resistance vessels in the peripheral and coronary circulations. Short-term trials of nicorandil versus monotherapy with another anti-anginal drug (diltiazem, amlodipine, propanolol) showed similar reductions in the frequency of episodes of angina and similar increases in total exercise capacity in both treatment groups.
- Ranolazine is the most recent first-line, FDA-approved drug for the medical management of angina. It works by blocking the “late sodium channel” in heart cells that are experiencing ischemia. Blocking this sodium channel improves the metabolism in ischemic heart cells, thereby reducing damage to the heart muscle and reducing angina symptoms.
- Ranolazine (Ranexa) has been shown to significantly improve the amount of time patients with stable angina are able to exercise before developing symptoms. The drug has been shown to actually reduce the risk of developing ventricular arrhythmias and atrial fibrillation; plus, QT interval prolongation risk is minimal or nonexistent with ranolazine.
- Headache, constipation, and nausea are the most common side effects associated with ranolazine.
Choice of Second-Line Drug
- Evidence suggests that long-acting nitrate and the newer anti-anginal agents (ivabradine, nicorandil, and ranolazine) are effective in the short term.
- A long-acting nitrate or one of the newer anti-anginal drugs (ivabradine, nicorandil, or ranolazine) can be used as monotherapy, or in combination with another anti-anginal agent, if first-line treatment is not tolerated or is contraindicated.
- Triple anti-anginal therapy should only be considered when patients have persisting symptoms and are being considered for revascularization, or when revascularization is not appropriate.
Angina: Secondary Prevention
The objectives of treatment in patients with stable angina are to relieve symptoms and improve outcomes, and secondary prevention measures are important to reduce the long-term risk of adverse cardiovascular events.
- The benefits of lipid-lowering therapy in people with coronary artery disease are established and a statin is recommended for all adult patients with clinical evidence of cardiovascular disease, including patients with stable angina.
- Aspirin in patients with stable angina reduces the risk of non-fatal myocardial infarction, taking into account the bleeding risk and comorbidity.
- ACE inhibitors may be indicated for the treatment of concomitant hypertension or heart failure, or after myocardial infarction.
Coronary Angiography and Revascularization
Randomized trials support myocardial revascularization by coronary artery bypass grafting (CABG) or by coronary angioplasty/percutaneous coronary intervention (PCI) to improve symptoms of angina relative to continued medical treatment. The main indication for revascularization in patients with stable angina is relief of symptoms. CABG provides slightly more effective relief of angina than PCI, but the absolute difference is small and decreases over time.
Progressive worsening of stable angina over time can lead to the development of unstable angina. A change occurs in the ASA status from ASA II to ASA III. The patient does not need much activity at this stage to trigger an attack. The coronary arteries are narrowed quite significantly. The patient could be on daily isosorbide (Isordil), or the patient uses a daily nitroglycerine patch to control the unstable angina. NTG pills are additionally used during an attack. Isosorbide (Isordil) is a long-acting nitrate and a very potent vasodilator. In addition to the previously mentioned medical medication for unstable angina, other therapies are also now in use.
Initial Medical Management of Unstable Angina
Medications used in the initial management of unstable angi/>