Heart Failure Flashcards
What is the definition for abnormal heart function?
Any cardiac structural or functional disorder leading to inadequate cardiac output &/or elevated ventricular filling pressures
Impairs the ability of the ventricle to fill (diastolic) or eject (systolic) blood
What is heart failure?
A complex clinical syndrome with signs and symptoms of:
- Reduced cardiac output (inability to meet metabolic demands of body or abnormally high cardiac pressures)
- Pulmonary or systemic congestion at rest or with stress
What are the mortality rates for heart failure?
10% will die after 30 days
20% will die after 1 year
50% will die after 5 years
Number of HF hospitalizations is a strong predictor of mortality
Is heart failure a stable condition?
No, it is a progressive condition
- Increasing frequency of decompensations punctuate gradual decline in function. Following each acute event, heart function does not return to previous level
What is the pathophysiology of heart failure?
Cardiac output (stroke volume x HR) is decreased in heart failure
Stroke volume is dependent on preload (muscle fiber stretching while filling), contracility (inherent ability of the myocardium to contract normally), afterload (muscle force required to overcome higher pressure in the aorta when pumping blood out)
What is the Frank-Starling Law?
It is the ability of the heart to alter contraction force based on changes in preload
Increased ventricle volume = Increased contactility = Increased stroke volume
Note: If the heart is overstretched (increased preload), it looses its ability to return equal force
What neurohormones do heart failure drugs target?
Norepinephrine
Angiotensin II
Aldosterone
Vasopressin
Pro-inflammatory cytokines
What are the four compensatory responses to reduced cardiac output?
- Increased pre-load (via Na+ and water retention):
a. Improves stroke volume - Vasoconstriction (maintains BP if CO is low)
- Tachycardia (helps maintain CO if stroke volume is low)
- Ventricular hypertrophy and remodelling (helps maintain CO)
What are the consequences of long-lasting increased pre-load?
Pulmonary and systemic congestion (blood is backing up)
What are the consequences of long-lasting vasoconstriction in response to reduced cardiac function?
Shunt blood from nonessential organs to brain and heart
Increased mycocardial oxygen demand
Increased afterload decreases stroke volume (activating further compensatory responses)
What are the consequences of ventricular hypertension and remodelling?
Increased risk of myocardial cell death, myocardial infarction, arrythmia, fibrosis
DIastolic and/or systolic dysfunction
What are some typical symptoms associated with heart failure?
- Breathlessness
- Orthopnea (dificulty breathing while lying down)
- Paroxysmal nocturnal dyspnea (waking up with SOB)
- Swelling of body
If a patient shows symptoms of heart failure, what else do they need to be diagnosed with heart failure?
Assess natriuretic peptides (gold standard biomarkers in HF)
Heart failure is present if patient has one of the following lab values:
- NT pro-BNP (greater than 125pg/mL)
- BNP (greater than 50pg/mL) (preferred in the SHA)
What are natriuretic peptides?
BNP
NT-proBNP (pro homone BNP)
They are synthesized and released by the ventricles in response to pressure or volume overload
BNPs promote natriuresis & diuresis, and attenute RAAS & SNS activation (opposes the action of heart failure compensatory actions, which is good)
What is neprilysin?
It is an enzyme that breaks down BNP
Neprilysin inhibitors like sacubitril are beneficial in reversing the negative heart failure compensatory actions
Can natriuretic peptide values alone be used to diagnose heart failure?
No, should be considered in relation to signs, symptoms, and information from diagnostic imaging
If BNP or NT-proBNP are elevated, what are the next steps?
Send for electrocardiogram & start or intensify neurohormonal blocking agents (ACEi, ARB, beta-blockers, MRAs)
What information can be gleaned from an ECG?
Size and shape of heart
Pumping capacity
Location and extent of damaged tissue (muscle, walls, valves)
Pressure estimates
Quality of ECG readings can vary by 10%
What are the three classifications of heart failure?
Chronic HF (persistent & progressive)
Acute/decompensated HF (gradual or rapid change in HF signs & symptoms, resulting in need for urgent therapy)
Advanced HF (frequent decompensations, mechanical devices, transplantation, palliative therapies)
Why is Left Ventricular Ejection Fraction significant?
Blood leaving left ventricle/blood entering left ventricle
Left ventricular ejection fraction can change depending on preload, contractility, and afterload. Therefore it is a good indicator for heart failure
What is HF-pEF?
Heart failure with preserved ejection fraction
In these HF patients, ejection fraction is above 50%. These patients may have problems with heart stiffness and ventricular relaxation (left ventricular hypertrophy)
Affects:
- Elderly
- Female
- DM, Atrial fibrillation, HTN
What is HF-mEF?
Heart failure with mid-range ejection fraction
In these HF patients, ejection fraction is between 41-49%
What is HF-rEF?
Heart failure with reduced ejection fraction
In these HF patients, ejection fraction is below 40%. These patients may experience systolic dysfunction, problems with the heart pump/contractility
Review slide 40 for the heart failure treatment algorithm?
What drugs are used in pharmacotherapeutic treatment of heart failure?
Initiate quadruple therapy
- ARNI (sacubitril/valsartan) or ACEi/ARB, then switch to ARNI
- Beta-blocker
- Mineralocorticoid receptor blocker
- SGLTi
Strive to initiate the above agents within 3 to 6 months after diagnosis, and titrate to target or maximally tolerated doses
What are the effects of ACEi drugs on CV health?
They prevent vasoconstriction (reduce BP) and especially post-glomerular (reduce GFR) and lower aldosterone associated sodium and H20 retention (reduced BP)
How are ACEi drugs titrated up?
Double dose every 1-3 weeks
What conditions are contraindicated for ACEi drugs?
- Bilateral renal artery stenosis
- History of angioedema
- Pregnancy
What are some caution situations for ACEi use?
- K+ greater than 5.2mmol/L, SCr greater than 220umol/L or eGFR under 30ml/min
- SBP less than 90 mmHg or sympotmatic hypotension
- Moderate to severe aortic stenosis
What are some drug interactions associated with ACEi drugs?
Increased risk of hyperkalemia associated with the following drugs:
- K+ supplements
- K+ sparing diuretics
- MRAs
- Renin inhibitors
- Trimethoprim (TMX)
- NSAIDs (should not be used in HF patients at all)
- Low salt substitutes (KCl)
Lithium (increased risk of lithium toxicity)
Is there a target for blood pressure in heart failure patients?
No fixed numbers (SBP around 90-100mmHg), but just before they start experiencing symptomatic hypotension
How do HCPs monitor K+ levels on patients on ACEis?
Lab work at baseline, & 1-2 weeks after initiating therapy and whenever increasing dose
How is renal function assessed in patients on an ACEi?
Lab work (SCr, BUN) at baseline, & 1-2 weeks after initiating therapy and whenver increasing dose
Increase in SCr or decrease in eGFR of up to 30% is acceptable
What is the use of ARBs over ACEi in heart failure treatment?
Use an ARB when patient has an ACEi intolerance
- Cough
- Angioedema
Why is ACEi first line for HF over ARBs?
ACEi simply have more evidence bc they have been out longer compared to ARBs
Do not combine ACEi and ARB, due to increased risk of hypotension, hyperkalemia, & renal dysfunction
Caution when starting patient on Entresto bc it contains valsartan and should not be used within 36 hours of ACEi dose
What ARBs are indicated for heart failure in Canada?
Candesartan:
- Start dose (4-8mg)
- Target dose (32mg daily)
Valsartan:
- Start dose (40mg BID)
- Target dose (160mg BID)
What drugs are found in Entresto?
Sacubitril/Valsartan
Review slide 57 for MOA for Entresto
What are some contraindications for Entresto?
Concurrent ACEi use (36 hour washout period ACEi <–> ARNI)
History of ACEi or ARB angioedema
What are the therapeutic doses of Entresto for heart failure?
Start dose (50-100mg BID)
Target dose (200mg BID)
Note dose values have been rounded
How is target dose for Entresto acheived?
Double dose in 3 to 6 weeks in patients on less than 50% of ACEi or ARB target dose
Double dose in 6 weeks for patients on more than 50% of ACEi or ARB target dose
What beta blockers are indicated for use in heart failure?
Bisoprolol
Carvedilol
Metoprolol
What is the mechanism of action for beta-blockers?
Block NE at the beta-adrenergic receptors (reduces heart hyperactivity, lowers HR)
Improves myocardial function by prolonging ventricular filling time (results in a more productive heartbeat)
What are the doses for the beta-blockers indicated for heart failure?
Carvedilol
- Starting (3.125mg BID)
- Target (25mg BID/50mg BID for patients over 85kg)
Bisoprolol
- Starting (1.25mg daily)
- Target (10mg daily)
Metoprolol
- Starting (12.5-25mg daily)
- Target (200mg daily)
How are beta-blockers titrated up to target dose?
Double dose every 2-4 weeks
What are some contraindications for beta-blockers in heart failure?
- 2nd or 3rd degree AV block or HR under 50bpm (Does not apply if patient has pacemaker)
- PR interval greater than 0.24 sec
- Severe/uncontrolled asthma
- Severe peripheral artery disease
What are some drug interactions associated with beta-blockers in heart failure?
- Verapamil, diltiazem, amiodarone, digoxin (increased risk of bradycardia/AV block)
- Clonidine (Increased risk of hypertensive crisis)
- Phenobarbital (reduced beta-blocker efficacy)
What are some adverse effects associated with beta-blocker use in heart failure?
- Hypotension
- Bradycardia
- Worsening HF symptoms
Can beta-blockers be stopped abruptly?
No, beta-blockers need to be tapered over 1 to 2 weeks
Which beta-blockers are cardioselective?
Bisoprolol and Metoprolol
Inhibit the beta-1 receptors in their heart (reduce HR)
Limited effect on BP
Which beta-blockers are non-cardioselective?
Carvedilol
Inhibits b-1 and b-2 receptors around the body (reduce HR, BP, airway obstruction)
What mineralocorticoid antagonists (MRAs) are indicated for heart failure in Canada?
Spironolactone
- Starting (12.5mg daily)
- Target (25-50mg daily)
Eplerenone
- Starting (25mg daily)
- Target (50mg daily)
What is the purpose of MRAs in heart failure treatment?
They are used to inhibit RAAS activation
How are MRAs titrated up to target dose?
Double dose every 4 to 8 weeks
What are some contraindications associated with MRAs?
Spironolactone and Eplerenon
- K+ is over 6mmol/L
Eplerenone:
- Severe hepatic impairment
What are some drug interactions associated with MRAs?
Both:
- Same as ACEi
Spironolactone:
- digoxin
Eplerenone:
- Caution for CYP3A4 inhibitors (only use 25mg max if concurrent therapy)
What are some adverse effects associated with MRAs?
Both:
- hyperkalemia
Spironolactone:
- Gynecomastia (dose-dependent), erectile dysfunction, menstrual irregularites
How are MRAs monitored once initiated?
Initial stage:
K+ and SCr baseline & test again 1 week after starting or increasing dose
Stable:
- Test monthly for 3 months in first year, then every 6 months after
At what CrCl is spironolactone use contraindicated?
When CrCl is below 30mL/min, spironolactone should not be used due to risk of hyperkalemia
Be more careful in monitoring to prevent kidney injury from hyperkalemia
Are spironolactone and eplerenone (both MRAs) similarly priced?
No, eplerenone ($80/month) is significantly more expensive vs spironolactone ($5-7/month)
Are MRAs effective in reducing BP in patients with heart failure?
No, MRAs do not reduce BP if it is normal
What SGLTis are indicated for heart failure in Canada?
Dapagliflozin
Empagliflozin