Ischemic Heart Disease Flashcards
What is the definition of ischemic heart disease?
Narrowing of one or more coronary arteries due to atherosclerosis
Also known as:
Coronary heart disease, coronary heart disease, atherosclerotic cardiovascular disease
What is a common outcome of ischemic heart disease?
Heart attack (myocardial infarction)
What percentge of deaths in Canada are due to a cardiovascular cause?
20% of deaths
Has MI risk declined in Canada?
Yes, 50 year olds have a lower MI risk vs. 50 year olds from decades away
Is the percentage of people who have lived through an MI increasing?
Yes, largely due to better healthcare and lower mortality rate
Do MIs increase death rate?
Yes
What is the death rate following an MI in patients over 80?
Almost 50% of MI patients over 80 will die within a year
What are the main types of cardiovascular diseases caused by artherosclerosis?
Ischemic heart disease
Cerebrovascular disease
Peripheral arterial disease
When do atherosclerotic plaque begin to build up?
Usually, start to build up early in one’s life.
These plaques can be present for decades without symptoms
What is the clinical presentation of coronary atherosclerosis?
Silent (asymptomatic) disease in most patients
Chronic, but stable angina
What are the classic signs of angina?
Dull, retrosternal discomfort/ache/heaviness
The pain may or may not radiate to jaw, neck, shoulders, arms
What is stable angina?
Stable angina is a problem of demand exceeding supply. The pain from ischemia will go away once resting
What is unstable angina?
Unstable angina is a result of inadequate supply regardless of demand. The pain from ischemia will not go away following rest
What are some triggers of stable angina?
SNS activity: Physical exertion, emotion
Exertion after a heavy meal: (reduced SNS and increased metabolic demands)
Metabolic demands: chills, fever, hyperthyroidism, tachycardia, exposure to cold, and hypoglycemia
Anemia: low oxygen content in blood (CO increases to rectify this issue)
Are coronary arteries supplied with blood during systole?
No, during systole the heart muscle contracts, including the coronary arteries that supply the heart with blood.
Only during diastole, when the heart is relaxed does blood flow into the coronary heart disease
How do atherosclerotic plaques cause stable angina?
Due to atherosclerotic plaques, the blood vessels are constricted. The constricted blood vessels limit supply, so the efferent vessels dilate to allow for more blood flow.
During exercise, the heart begins to beat faster and needs more blood supply, but the vessels have been maximally diated during rest due to the narrowed vessel. When demand increases, the efferent vessels cannot dilate any further causing supply to fall below demand.
What changes can relieve stable angina?
Stable angina is relieved by rest and nitroglycerin
What is the function of nitrate drugs?
A class of drugs that cause vasodilation. Nitrate drugs preferably dilate veins over arteries
They are all prodrugs and are converted into NO in the body
How is NO released endogenously?
NO is a paracrine hormone that is synthesized by endothelial cells to signal adjacent smooth muscle cells that surround vessels
How does NO treat stable angina?
NO reduces venous pressure. The consequence of this is preload or venous return is lower. This reduces heart workload, so CO declines. This reduced heart activity reduces demand to a level that can be accommodated with a lowered blood supply. This takes the heart muscle out of ischemia
How are different severities of angina ranked?
Class I angina is the lowest severity (walking, and climbing stairs does not cause angina, but prolonged exertion at work or recreation)
Class IV is the highest severity, and these patients have the inability to carry on any physical activity without discomfort
What are some pieces of information that would rule out angina in the diagnosis of chest pain?
Occurs after heavy meals
Associated with belching and gas
Relieved by food, liquids, antacids
Occurs with inspiration/expiration
What is a good diagnostic test for angina?
Excercise stress test
How are readings from a exercise stress test interpreted?
As the reading occurs, the treadmill increases incline and speed. Patients are asked to go to as long as they get tired or have chest pain.
If the patient can exercise without having angina during a prolonged session of exercise, we can rule out cardiac atherosclerosis
What does angina look like on an ECG chart?
Depression of the S-T segment of the ECG relative to the Q-R segment
What is the following step after a positive finding of ischemia in the stress test?
Coronary angiogram
Is stable angina a medical emergency?
No, as long as rest and NO resolves angina
What are some ways to evaluate coronary artery blood flow?
Cardiac catheterization and angiography
What is a common series of drugs prescribed to people with coronary artery disease?
ABCKDE
Antiplatelets
BP medications
Cholesterol-lowering medications
K-CKD
Diabetes medications
Exercise/diet/lifestyle changes
What are the goals of therapy for angina?
Goals of therapy should include both symptom relief and protection
What are some drugs that are indicated to prevent or reduce the frequency/intensity of stable angina episodes?
beta-blockers
DHP CCBs
Non-DHP CCBs
Nitrates
Ranolazine
How do beta-blocker prevent angina?
Reduce CO, which reduces demand in the heart tissue
b1 selective agents are preferred due to lower risk of:
ED
Peripheral circulation problems
Interaction with b2 agonists
What are some monitoring considerations in beta-blocker use?
Reduced HR and BP
Signs of poor CO
Reduced circulation (Reynauds’s)
Respiratory (Asthma)
Diabetes (mask hypoglycemia)
Are non-selective b-blockers and a-blockers used to treat stable angina?
Not typically used for stable angina (unless complications exist)
Are non-DHP CCBs used to treat stable angina?
Yes, they just higher intensity agents
What are some contraindications for non-DHP CCB use?
Systolic dysfunction (low EF/systolic HF)
Already on a b-blocker
Bradycardia or AV block
What is AV block?
When the electrical signal that controls your heartbeat is partially or completely blocked
What do the different AV block degrees look like on an ECG?
1st degree: P-R interval delay
2nd degree: Intermitently dropped QRS
3rd degree: P and QRS are independent
Can non-DHP CCBs be given to people with AV block?
Only to patients with 1st degree AV block
They cannot be used in patients with 2nd ad 3rd degree AV block
This is because bradycardia and 1st degree heart block can be caused by non-DHP CCB or b-blocker use
Are DHP CCBs used to treat stable angina?
Yes, we use this drug class if the patent also has high BP
DHP CCBs cause vasodilation to reduce angina. They can also be combined with b-blockers unlike non-DHP CCBs
Great as a monotherapy agent for patients with bradycardia or intolerance to b-blockers
Can NO be used in combination with b-blockers and CCBs for angina?
Yes, we can use nitroglycerin to eliminate angina
Do patients have to worry about NO intolerance when used as a agent for stable angina?
Yes, patients should ensure that they do not take nitrates for 10-14 hours every day to prevent tolerance from occurring
Can nitrate drugs prevent heart attacks?
No, nitrates only eliminate angina. Nitrates have no cardio-protective activity (symptomatic treatment)
What is the utility of ranolazine in treating stable angina?
It is usually indicated as add-on therapy for people that are not fully responding to first-line agents
No impact on BP or HR
What are some options to treat coronary atherosclerosis?
Drug therapy
Revascularization:
Coronary artery bypass grafting
Angioplasty/stent implantation
Fibrinolytic medication (only for acute emergencies)
What is involved in dual antiplatelet therapy (DAPT)?
It helps reduce clotting activity.
Refers to the use of ASA + PSY12 inhibitor (ADP inhibitor)
Why was DAPT introduced in patients with post-stent implantation?
When stents are blown open, the metal mesh can smash against the lumen lining of coronary arteries. The damage can cause the formation of a clot around the stent
How are stents implanted differently today?
Now stents are coated with an immunosupressant that reduces the activation of inflammatory cytokines and cell proliferation following stent implantation
How to monitor for DAPT?
Bloody and dark stools, hematemesis, bruising
GI upset
RBC, Hb, Hct, platelet count
How long is DAPT therapy in most cases?
Usually 1 year if they are not at a high risk of bleeding
What is the length of DAPT therapy in patients who have a high risk of bleeding?
1 month
What percentage of a coronary artery needs to be obstructed before symptoms of coronary artery disease are experienced?
above 75%
Are heart attacks as dramatic as they are shown in media?
No, lots of people do not realize they have a heart attack
It is associated with severe chest pain and sweating
What are the two categories of myocardial infarction?
ST elevation MI (STEMI)
Non-ST elevation MI (NSTEMI)
What types of patients get heart attacks?
Average age of first MI is late 60s
Male to female ratio (3:2)
Do women experience MI differently?
In addition to severe chest pain, women also show symptoms of sweating, dyspnea, nausea, abdominal pain, fainting
What assessments are used in the ER for MIs?
- Get the story from the patient
- 12 lead ECG
- Blood tests for biomarkers of cardiac cell death
What ECG results suggest an MI has occurred in a patient?
ST elevation almost always is associated with severe MIs (STEMI)
Q-waves can appear following or during a STEMI (permanent change)
Although associated with stable angina, ST depression can also indicate an MI
What biomarkers suggest an MI has occurred in a patient?
Cardiac troponins are the most sensitive and specific biomarkers for cardiac cel death (caused by an MI)
Troponin levels in the blood can linger for days following a MI
Can elevated troponin levels in the blood indicate conditions other than a MI?
Yes, troponin levels can be elevated for non-MI reasons
What are some common treatments for MI care?
Oxygen
ASA +/- ADP inhibitor
Nitroglycerin
b-Blocker
IV anticoagulants
What is the efficacy of b-blockers in post-MI care?
It reduces deaths by 27%
Are b-blockers more useful today?
No, with the adoption of stent revascularization for MIs, the damage done to hearts due to an MI has been reduced.
B-blockers prevent damaged hearts from beating to fast, but now hearts are damaged less following MIs. The potential benefit of using b-blockers is lower on average
Are fibrinolytics useful in MIs?
Exclusively in patients who cannot be revascularized immediately. Often done at smaller and remote hospitals
revascularization/PCI should be performed within 12h of onset of symptoms
How are patients pepared for PCI/revascularization?
Pre-PCI Antiplatelet therapy
Anticoagulant therapy (DAPT)
What agents are used in Pre-PCI antiplatelet therapy?
Aspirin
and a loading dose of an ADP inhibitor (Clopidogrel, Ticagrelor, and Prasugrel)
What anticoagulants used in anticoagulants?
LMWH
UFH
Bivalirudin
What ADP inhibitors are prodrugs?
Clopidogrel and Prasugrel are prodrugs and irreversible antagonists
Ticagrelor is not a prodrug and it also is a reversible inhibitor
What drugs are given on Day 1 following revascularization procedures?
DAPT therapy
b-blocker
ACEi
Statin
Nitroglycerin PRN, but he won’t need it due to resvascularization
What are some risk factors against the use of DAPT?
Patient is on DOAC, NSAIDs, or prednisone
Over 75
Frail
Anemic (Hb <110)
Low kidney function (under 45ml/min)
Lower body weight (60kg)
Has ben to the hospital for bleeding in past 1 year
Prior stroke
What is an important dosing consideration for Prasugrel?
10mg daily for most patients
5mg to patients over 75 or weigh less than 60kg
What is a interesting elevated adverse reaction to ticagrelor?
Ticagrelor use is often associated with 2x more dyspnea (13.8%) compared to other ADP inhibitors like Clopidrogrel
Are statins a common drug prescribed to people with atherosclerotic disease?
Yes, atherosclerotic disease indicates statins regardless of cholesterol levels
Does nitroglycerin prevent heart attacks?
No, it only eliminates angina. Increased angina should prompt the patient to see their MD to review their heart health
What are the recommendations for b-blocker use in the different types of MI?
STEMI - absolute indication
STEMI without residual dysfunction - use for 3 years and re-evaluate
NSTEMI without residual dysfunction - only consider b-blocker, might not be effective enough for use
*The les severe the MI, the less benefit to be realized
What are some strong indications for ACEi use?
Ejection fraction below 40%
HTN
CKD
What MI patients are prescribed mineralocorticoid receptor antagonists?
Those that develop heart failure following, but do not use if patient has significant renal dysfunction
What is CABG?
CABG is an abbreviation for Coronary Artery Bypass Grafts
Can ADP inhibitor use affect CABG procedures?
Yes, the use of anti-platelet drugs are a hazard in a surgical procedure like CABG if used within days of procedure (involves open heart surgery)
What is the typical anti platelet therapy following CABG?
ASA only
What is a common ECG sign for a NSTEMI?
ST-depression (less severe compared to ST-elevation)
How to differentially diagnose unstable angina and a NSTEMI?
They both may show ST-depression, but in a NSTEMI, the amount of troponins in the blood also increases
Are PCIs required urgently in most NSTEMI cases?
No, they can be elective procedures at a later date
What are some factors that can make MDs favour invasive treatments for MIs?
STEMI
Refractory angina
Hemodynamics/electrical instability
HIgh risk features (Diabetes, previous MI, HF, etc)
Are anti platelet drugs avoided by patients with atrial fibrillation?
Atrial fibrillation or arrhythmia can cause clots in the atria to form. The use of DAPT is likely to cause further bleeding, increasing the chance of a carotid embolism.
What is the link between an MI and atrial fibrillation?
Ischemia in an MI causes cell death in a localized region of the heart. When conduction signal are sent across the heart, these regions of dead tissue may delay or weaken the signals
Is PCI indicated for unstable angina?
Yes, it isn’t as urgent as a STEMI, but it can be scheduled as an elective procedure
