• Yes, if MI has occurred within the past 30 days. Functional capacity (FC) should be determined before proceeding with professional oral care post-30 days (see immediately below).
• No, if the patient/client has a history of MI > 30 days ago, with no evidence of cardiac symptoms and is able to meet a four-metabolic equivalent (MET) demand during daily activities, and who has a systolic blood pressure < 180 mm Hg and a diastolic pressure < 110 mm Hg with a normal pulse rhythm. Under these circumstances, non-invasive dental hygiene procedures can be provided with little to no risk for a cardiovascular event (including re-infarction). See Box 1 for determination of functional capacity (four-MET level).

Is medical consult advised? 

• Yes, if patient/client’s medical status is suspected to be unstable (e.g., complaints of chest pain, symptoms compatible with heart failure such as shortness of breath or ankle swelling, etc.) and/or drug toxicity (e.g., digitalis) is suspected. Even if a recent stress test does not reveal poor myocardial function, the patient/client with a recent MI (i.e., within past two months) should undergo a consultation with a cardiologist to determine that FC meets the four-MET level before proceeding with professional oral care.

• Yes, periodontal debridement should be delayed 30 days after an MI. Functional capacity (FC) should be determined before proceeding with professional oral care post-30 days (see immediately below).
• No, if the patient/client has a history of MI > 30 days ago, with no evidence of cardiac symptoms and is able to meet a four-metabolic equivalent (MET) demand during daily activities, and who has a systolic blood pressure < 160 mm Hg and a diastolic pressure < 100 mm Hg with a normal pulse rhythm. Under these circumstances, invasive dental hygiene procedures can be provided with little to no risk for a cardiovascular event (including re-infarction). See Box 1 for determination of functional capacity (four-MET level).

Is medical consult advised?

• Yes, if patient/client’s medical status is suspected to be unstable (e.g., complaints of chest pain, symptoms compatible with congestive heart failure such as shortness of breath or ankle swelling, etc.) and/or drugs have been prescribed that may necessitate care plan alterations (e.g., antiplatelet agents [such as clopidogrel, ticagrelor, and prasugrel] or anticoagulants such as warfarin and direct oral anticoagulants) and/or pacemaker shielding is unclear and/or drug toxicity (e.g., digitalis) is suspected. Also, for the patient/client with a recent MI (i.e., within past two months) who has undergone a recent stress test that does not reveal poor myocardial function, a consultation with a cardiologist should occur to determine that FC meets the four-MET level before proceeding with professional oral care.

Is medical clearance required? 

• Yes, if there are medical complications or comorbid conditions that may impact patient/client safety. Oral procedures should be deferred for a patient/client unable to attain the four-MET level until further medical testing has been completed to quantify the level of cardiac risk involved with treatment — the decision to proceed with dental hygiene treatment should be made in conjunction with the patient/client’s cardiologist. Periodontal debridement is generally safe for individuals with neither major nor intermediate predictors of clinical risk (see appended Box 2) and moderate or excellent FC (four METs or greater). For persons with intermediate predictors of clinical risk and moderate to excellent FC, dental hygiene procedures pose little likelihood of peri-procedural MI or death.

Is antibiotic prophylaxis required? 

• No. (Antibiotic prophylaxis is not indicated for patients/clients who have had balloon angioplasty with placement of a coronary stent or who have undergone a coronary artery bypass graft — CABG — procedure. Similarly, antibiotic prophylaxis is not generally indicated for patients/clients who have cardiovascular implantable devices, including cardiac pacemakers [intravascular or epicardial] and implantable cardioverter devices [ICDs].)

Is postponing treatment advised?

Functional capacity approach:

• Yes, if the MI has occurred within the past 4 to 6 weeks.
• Yes, if functional capacity is less than four METs.

Other considerations:

• If the patient/client is taking a non-ASA antiplatelet agent (such as ticagrelor, prasugrel, or clopidogrel) as part of dual antiplatelet therapy (DAPT) after undergoing percutaneous coronary intervention (PCI) post-MI, elective dental/dental hygiene procedures involving significant bleeding may need to be deferred until the non-ASA antiplatelet agent is stopped either permanently (typically one year³) or temporarily, informed by prevailing guidelines and under medical guidance.⁴ Routine dental/dental hygiene procedures with low procedural bleeding risk, however, can usually proceed without interruption of the antiplatelet regimen, in the absence of other reasons for deferral. See “Oral management implications” below for further details.
• For further guidance regarding patients/clients taking antiplatelet agents (or direct oral anticoagulants [DOACs] or warfarin), refer to Direct Oral Anticoagulants and Oral Antithrombotic Fact Sheet. Self-initiation of invasive dental hygiene procedures is contra-indicated (in accordance with the “any blood disorders” contraindication specified in Ontario Regulation 501/07 pursuant to the Dental Hygiene Act). Antiplatelet agents, DOACs, and warfarin elevate risk of bleeding.

Box 1: Determination of Functional Capacity

The medical interview should seek to determine the patient/client’s FC. The ability to perform daily tasks that require cardiac reserve is significantly related to cardiac risk during treatment and correlates with maximum oxygen uptake by treadmill stress testing. The following questions reflect abilities that meet the four-MET level:

• Can you walk up a flight of stairs carrying groceries?
• Can you run a short distance?
• Can you participate in recreational activities such as doubles tennis, play nine holes of golf, or dance for at least five minutes?

• Potential risks relevant to dental hygiene care post-MI include cardiac arrest, new myocardial infarction, angina pectoris, heart failure (HF), bleeding tendency secondary to antiplatelet/anticoagulant use, and electrical interference with a unipolar pacemaker.
• Typical post-MI drugs, depending on risk profile, include antihypertensives (often a beta-blocker and an angiotensin-converting enzyme inhibitor — ACEI), anti-cholesterol agents, and low-dose ASA.
• Medical complications in the dental hygiene setting can be minimized by booking short appointments and by terminating the appointment if the patient/client becomes fatigued or short of breath, complains of chest pain, or develops change in pulse rhythm or rate; these signs and symptoms should prompt medical referral. 
• Because blood pressure is lowest in the afternoon, afternoon appointments may be preferred in post-MI patients/clients prone to hypertension. Alternatively, morning appointments may be preferred when the patient/client is well rested and has a greater physical reserve. The patient/client should be engaged to determine the best time of day for an appointment. A stress reduction protocol may be utilized where indicated.
• General management strategies for patients/clients with a past history of MI without ischemic symptoms and no other risk factors include the following: short appointments in the morning, comfortable chair position (avoiding rapid position changes⁵), pretreatment vital signs, and availability of nitroglycerin.
• In addition to medical management, many persons experiencing MI undergo percutaneous coronary intervention (i.e., angioplasty + stent). To avoid stent thrombosis, patients/clients are typically placed on dual antiplatelet therapy (DAPT; e.g., ASA⁶ and another antiplatelet agent) following stent placement in the coronary arteries. DAPT is usually continued for at least a year after implantation⁷; elective surgery or procedures involving significant bleeding should usually be delayed until after this one-year period. Following cessation of DAPT, single antiplatelet therapy (SAPT) is usually implemented, often with continuation of low-dose ASA for life.
• Dual antiplatelet therapy is also used to treat patients/clients with acute coronary syndrome (ACS, which includes MI and unstable angina pectoris) who do not undergo revascularization. Duration of DAPT may be 12 months or more, followed by life-long SAPT (often low-dose ASA).
• In order to appropriately proactively manage potential peri-procedural or post-procedural bleeding (and in accordance with regulations pursuant to the Dental Hygiene Act), the dental hygienist should contact the patient/client’s cardiologist/physician regarding the patient/client’s antiplatelet regimen and optimal dental hygiene management. This medical consultation/clearance should inform any consideration to temporarily stop antiplatelet medications (in particular, ticagrelor, prasugrel, or clopidogrel) prior to dental/dental hygiene procedures. Antiplatelet medications should not be discontinued prematurely, even temporarily, given their importance in minimizing the risks of stent thrombosis and re-infarction, and discontinuation of these agents before dental hygiene procedures is usually unnecessary. However, if deemed appropriate by the attending cardiologist/physician, the non-ASA antiplatelet agent may be temporarily stopped several days (possibly 5 to 10 days, depending on the specific agent) before invasive dental/dental hygiene care that involves tissue manipulation.
• There is virtually no dental hygiene indication to discontinue low-dose ASA treatment in patients/clients with a history of MI. Other nonsteroidal anti-inflammatory drugs (NSAIDs), however, should generally be avoided in patients/clients whose cardiac history includes an MI.⁸  
• If scaling procedures are planned for a patient/client on the anticoagulant warfarin (e.g., for atrial fibrillation), the patient/client’s physician should be contacted to confirm that the PT ratio (prothrombin time) will be two times normal or less, or international normalized ratio (INR) is less than 3.0.
• If the patient/client is taking a direct oral anticoagulant (DOAC) for reduction in thromboembolic events post-MI (or otherwise), medical consultation/clearance should be sought. It should be a physician (not a dentist) who recommends interruption of a DOAC for a dental/dental hygiene procedure (which is usually not indicated for dental hygiene procedures).
• Digitalis (e.g., digoxin), while less commonly used now than historically, is sometimes used as part of post-MI medical therapy to increase contractility of the heart, particularly if heart failure is present. The dental hygienist should be alert to signs of digitalis toxicity in patients/clients (e.g., anorexia, nausea, vomiting, altered vision, neurologic abnormalities, and facial pain), which should prompt medical referral. If not detected and managed early, digitalis toxicity can lead to cardiac arrhythmias, which may be potentially life threatening.
• Antiarrhythmic agents used post-MI (e.g., quinidine, procainamide) may result in nausea and vomiting, as well as hypotension. Oral ulcerations may indicate agranulocytosis⁹.
• Cardiac pacemakers may be implanted in patients/clients post-MI who experience certain dysrhythmias (arrhythmias). These devices vary in their sensitivity to electrical interference. Newer bipolar models provide shielding against interference, and they typically do not require any special consideration during dental hygiene care. Older unipolar models are less protected from electrical interference and can be adversely affected by mechanized dental instruments. If in doubt regarding model safety, the dental hygienist should seek the advice of the patient/client’s cardiologist prior to the use of mechanized devices. Nonelectrical alternatives to avoid functional interference (e.g., manual instruments) should be considered in patients/clients with unipolar pacemakers. Care should be taken in an open clinical setting where electrical dental equipment may be used for an adjacent patient/client. 
• Persons who have had an MI are at elevated risk of future adverse coronary events. Re-infarction or other emergency situations in the dental hygiene office need to be managed by emergency medical services (EMS).
• Annual influenza immunization may be associated with some degree of protection from myocardial infarction. Thus, dental hygienists should encourage post-MI patients/clients to receive an annual flu shot, and dental hygienists themselves should undergo annual immunization to decrease disease transmission. Similarly, because COVID-19 infection can cause acute myocardial injury (including MI), immunization against this disease should also be considered for patients/clients and dental hygienists in accordance with prevailing recommendations of the National Advisory Committee on Immunization and the Ontario Ministry of Health.
• Smoking cessation should be encouraged if patient/client still smokes post-MI.¹⁰ 

• None are specific to myocardial infarction or coronary atherosclerotic heart disease¹¹; however, medications used in post-MI care and its complications can result in oral changes such as stomatitis (e.g., from antiarrhythmic use).
• Side-effects of anti-hypertensive medications that may be used in post-MI patients/clients include: 
  • chronic cough (e.g., angiotensin converting enzyme inhibitors — ACEIs); 
  • taste changes (e.g., ACEIs, beta blockers, alpha-adrenergic blockers); 
  • angioedema of lips, face, tongue (ACEIs, angiotensin II receptor blockers — ARBs); 
  • upper respiratory tract infections (e.g., ARBs); 
  • gingival hyperplasia (e.g., calcium channel blockers — CCBs); 
  • xerostomia (e.g., thiazide diuretics and alpha-adrenergic blockers); 
  • lichenoid reactions (e.g., thiazide diuretics and beta blockers); and 
  • lupus-like oral and skin lesions (e.g., direct vasodilators).

Refer to Hypertension Fact Sheet and Advisory for more information.

• Excessive salivation and an enhanced gag reflex (particularly in the elderly) can occur with the use of glycosides (e.g., digoxin), which are used to treat heart failure and atrial fibrillation.
• In rare cases, patients/clients with angina occurring as a manifestation of atherosclerotic heart disease may experience pain referred to the neck, lower jaw, or teeth. Its cardiac origin is suggested by a pattern of onset of pain with physical activity and its disappearance with rest.

• Myocardial infarction (MI) results from a reduction in blood flow through one or more of the coronary arteries, resulting in infarct, or death, of myocardium (heart muscle).
• Peak mortality following an MI occurs in the first year, primarily resulting from the increased electrical instability of the myocardium (heart muscle) after the infarction.
• Inflammation may contribute to myocardial infarctions, strokes, and other cardiovascular events. Dental hygiene procedures such as scaling and root planing may release bacteria into the bloodstream, potentially increasing vascular inflammation and thereby increasing the risk of a vascular event.
• Heart failure (HF) — where a damaged heart can no longer pump sufficient blood to the body — is a potential post-MI complication. Signs/symptoms include swelling of the ankles, as well as shortness of breath and coughing (due to fluid accumulation in the lungs).
• Patients/clients who have experienced a myocardial infarction may experience depression, fear, and disturbances in body image, which are associated with changes in lifestyle (e.g., dietary restrictions, exercise, and maintaining low stress levels).

Box 2: Clinical Predictors of Increased Perioperative Cardiovascular Risk

Major

• Unstable coronary syndromes
  • Acute or recent MI¹² with evidence of ischemic risk
  • Unstable or severe angina
• Decompensated heart failure
• Significant arrhythmias, including
  • High-grade atrioventricular block
  • Symptomatic ventricular arrhythmias with underlying cardiac disease
  • Supraventricular arrhythmias with uncontrolled ventricular rate
  • Symptomatic bradycardia
• Severe cardiac valve disease
  • Severe aortic stenosis
  • Symptomatic mitral stenosis

Intermediate

• History of ischemic heart disease (including mild angina pectoris)
• Previous MI by history or ECG
• History of compensated or prior heart failure
• History of stroke
• Diabetes mellitus (especially Type 1)
• Renal insufficiency

Minor

• Advanced age (> 70 years)
• Abnormal ECG (left ventricular hypertrophy, left bundle-branch block, ST-T wave abnormalities)
• Rhythm other than sinus (e.g., atrial fibrillation)
• Low FC (e.g., unable to climb one flight of stairs with a bag of groceries)
• Uncontrolled systemic hypertension

Boxes 1 and 2 adapted from:

Pickett F. American College of Cardiology/American Heart Association updated guidelines for peri-operative care cardiovascular evaluation prior to noncardiac surgery: implications for dental hygiene treatment in post-myocardial infarction. American Dental Hygienists’ Association; 2008. + Bowen DM (ed.) and Pieren JA (ed.). Darby and Walsh Dental Hygiene: Theory and Practice (5^th edition). St. Louis: Elsevier; 2020. Sourced from Fleisher LA, Beckman JA, Brown KA et al. ACC/AHA 2007 guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation 2007:116(17):1971-1996.

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* Includes oral hygiene instruction, fitting a mouth guard, taking an impression, etc.
** Ontario Regulation 501/07 made under the Dental Hygiene Act, 1991. Invasive dental hygiene procedures are scaling teeth and root planing, including curetting surrounding tissue.