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(ejection fraction [EF] <40%) as an alternative to an ACE/ARB (4)[A].

–In patients who have been stable on an ACE or ARB, morbidity and mortality may be further reduced (all-cause mortality reduction approximately NNT 33 over 2 years treatment) by replacement with an ARNI (4)[A], with careful monitoring needed for hypotension and angioedema.

–Loop diuretics

May need to be given IV initially and then orally as patient stabilizes

–Furosemide, 40 to 120 mg/day or TID (3)[A]

–β-Blockers

Use with caution in acutely decompensated or low-cardiac output states.

Initiate with low doses and titrate as tolerated.

–Metoprolol succinate, 12.5 to 200 mg/day; carvedilol, 3.125 to 25 mg BID; or bisoprolol, 1.25 to 10 mg/day (3)[A]

–Patients with New York Heart Association (NYHA) II to IV heart failure, EF <35%, on standard therapy: aldosterone antagonists: spironolactone or eplerenone (3)[A]

–Digoxin, 0.125 to 0.250 mg/day for symptomatic patients on standard therapy (3)[B]

–Combination hydralazine/isosorbide dinitrate is first-line treatment in African American patients with class III to IV symptoms already on standard therapy and for all patients with reduced EF and symptoms incompletely responsive to ACE inhibitor and β-blocker (3)[A].

Contraindications

–β-Blockers: low cardiac output, 2ndor 3rd-degree heart block

–Avoid use of diltiazem and verapamil in patients with systolic dysfunction.

–Aldosterone antagonists: oliguria, anuria, renal dysfunction

–Loop diuretics: hypokalemia, hypomagnesemia

–ACE inhibitors: pregnancy, angioedema

–ARNIs: patients currently on an ACE inhibitor or who have taken one in the past 36 hours, patients with a history of angioedema

Precautions

–In patients with chronic kidney disease, digoxin dosage should be ≤0.125 mg/day and drug levels followed carefully to avoid toxicity.

–Closely monitor electrolytes.

–ACE inhibitors and ARNIs: Initiate with care if BPis low.

–β-Blockers: Avoid in patients with evidence of poor tissue perfusion; they may further depress systolic function.

–Milrinone, dobutamine: long-term use associated with increased mortality

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Medications to avoid

–NSAIDs

–Glitazones

–Cilostazol

Second Line

Inotropic therapy (e.g., dobutamine or milrinone) for cardiogenic shock and support prior to surgery or cardiac transplantation (3)[B]

Continuous inotrope infusion may be considered in stage D outpatients for symptom control in those who are not eligible for transplantation or mechanical circulatory support (3)[B].

ISSUES FOR REFERRAL

Management by a heart failure team improves outcomes and facilitates early transplant referral.

ADDITIONALTHERAPIES

Prophylactic implantable cardioverter-defibrillator (ICD) should be considered for patients with a left ventricular ejection fraction (LVEF) <35% and mild to moderate symptoms (3)[A].

Cardiac resynchronization therapy (CRT) is recommended and should be considered for patients in sinus rhythm with a QRS >150 ms, LVEF <35%, in functional class (FC) I to III, and ambulatory FC IV patients (3)[A].

Patients with severe, refractory heart failure with no reasonable expectation of improvement should not be considered for an ICD. Palliative care is a reasonable option in such patients.

Consideration of an LV assist device as “permanent” or destination therapy or cardiac transplantation is reasonable in selected stage D patients.

ONGOING CARE

DIET

Low fat, low salt, fluid restriction

PROGNOSIS

~20–40% of patients in NYHAFC IV die within 1 year. With a transplant, 1- year survival is as high as 94%.

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COMPLICATIONS

Worsening congestive heart failure syncope, renal failure, arrhythmias, or sudden death

REFERENCES

1.Maron BJ, Towbin JA, Thiene G, et al. Contemporary definitions and classification of the cardiomyopathies: an American Heart Association Scientific Statement from the Council on Clinical Cardiology, Heart Failure and Transplantation Committee; Quality of Care and Outcomes Research and Functional Genomics and Translational Biology Interdisciplinary Working Groups; and Council on Epidemiology and Prevention. Circulation. 2006;113(14):1807–1816.

2.Seward JB, Casaclang-Verzosa G. Infiltrative cardiovascular diseases: cardiomyopathies that look alike. J Am Coll Cardiol. 2010;55(17):1769– 1779.

3.Yancy CW, Jessup M, Bozkurt B, et al. 2017 ACC/AHA/HFSAfocused update of the 2013 ACCF/AHAguideline for the management of heart failure: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Failure Society of America. Circulation. 2017;136(6):e137–e161.

4.McMurray JJ, Packer M, Desai AS, et al; for PARADIGM-HF Investigators and Committees. Angiotensin-neprilysin inhibition versus enalapril in heart failure. N Engl J Med. 2014;371(11): 993–1004.

SEE ALSO

Alcohol Use Disorder (AUD); Alcohol Withdrawal; Amyloidosis; Diabetes

Mellitus, Type 1; Diabetes Mellitus, Type 2; Hypertension, Essential;

Hypertrophic Cardiomyopathy; Hypothyroidism, Adult; Protein–Energy

Malnutrition; Rheumatic Fever; Sarcoidosis

Algorithm: Congestive Heart Failure: Differential Diagnosis

CODES

ICD10

I42.9 Cardiomyopathy, unspecified

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I42.0 Dilated cardiomyopathy

I42.5 Other restrictive cardiomyopathy

CLINICALPEARLS

Cardiomyopathy represents the end-stage of a large number of disease processes involving the heart muscle.

Ischemic, hypertensive, postviral, familial, alcoholic, and incessant tachycardia-induced are the most common cardiomyopathy varieties seen in the United States.

Core therapy for heart failure applies salt restriction, diuretics, ACE inhibitors, β-blockers, digoxin, and electrical treatments, such as cardiac resynchronization and implantable defibrillators, as appropriate.

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CAROTID SINUS HYPERSENSITIVITY

Amal Shine, MD Anub G. John, MD Hugh Peterson, MD, FACP

BASICS

DESCRIPTION

The carotid sinus, located at the bifurcation of the internal and external carotid arteries, contains baroreceptors that are responsive to increases or decreases in arterial pressure. It plays a central role in blood pressure (BP) homeostasis.

An endogenous increase in BPor external pressure applied to a carotid sinus causes an increase in the baroreceptor firing rate and activates vagal efferents and/or inhibits the sympathetic discharge to the heart and blood vessels, resulting in a slowing of the heart rate and/or drop in BP.

In carotid sinus hypersensitivity (CSH), stimulation of one or both carotid sinuses causes an exaggerated baroreceptor response that can result in dizziness or syncope.

CSH is defined as asystole for at least 3 seconds and/or a drop in systolic BP of at least 50 mm Hg during carotid sinus massage (CSM).

CSH is generally divided into three subtypes, based on response to CSM:

–Cardioinhibitory (70–75%): asystole for at least 3 seconds

–Vasodepressor (5–10%): fall in systolic BPof at least 50 mm Hg

–Mixed (20–25%): combination of the first 2 subtypes

Carotid sinus syndrome (CSS) typically (but not consistently) refers to CSH with syncope and may be classified as:

–Spontaneous CSS: syncope after accidental mechanical manipulation (trigger) of the carotid sinuses (e.g., shaving, tight collars, or tumors)

–Induced CSS: syncope diagnosed by CSM although no mechanical trigger is found

EPIDEMIOLOGY

Disease of elderly; virtually unknown in people aged <50 years

More prevalent in males by ratio of 4:1

Typical patient is an older man, usually with a history of coronary artery disease (CAD) and hypertension (HTN), with right CSH > left CSH. CSH may be a cause of the symptoms in 30% of elderly patients with

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unexplained syncope (1).

CSH was also present in 35% of community-dwelling older individuals without any symptoms of syncope, falls or drop attacks (2).

ETIOLOGYAND PATHOPHYSIOLOGY

The exact mechanism of CSH remains unknown. Changes in any part of the reflex arc or the target organs may give rise to this condition, or it may be a part of a generalized autonomic disorder associated with autonomic dysregulation.

Associated with resting sympathetic overactivity and increased baroreflex sensitivity (2)

Bradycardia and asystole seen in cardioinhibitory and mixed CSH subtypes appear to be mediated by vagal efferents, whereas vasodilatation and arterial hypotension in the vasodepressor and mixed subtypes are attributed to decrease sympathetic tone.

Symptomatic CSH has been shown to be associated with impaired cerebral autoregulation, and in asymptomatic CSH, it was found to be normal (2).

Atherosclerosis may diminish carotid sinus compliance, resulting in a reduction in afferent impulse traffic in the baroreflex pathway (3). CSH is often idiopathic but can be caused by:

–Carotid body tumors

–Inflammatory and malignant lymph nodes in the neck

–Extensive scarring from prior neck surgery in the area of the carotid sinus

–Metastatic cancer

RISK FACTORS

Male gender

Advanced age

CAD

HTN

DM

COMMONLYASSOCIATED CONDITIONS

Sick sinus syndrome

Atrioventricular block

CAD

HTN

Orthostatic hypotension

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Vasovagal syncope

Alzheimer disease

Parkinson disease

DIAGNOSIS

HISTORY

Recurrent syncope: usually sudden, unexplained, of short duration, seemingly spontaneous, and with complete recovery, although fractures and other injuries may occur

Unexplained falls: Evidence of a causal relationship is suggested between falls and the cardioinhibitory subgroup.

Dizziness: Manifests as transient light-headedness or presyncope but not usually as true vertigo; associated more with vasodepressor and mixed subtypes

Syncope may be associated with prodrome or retrograde amnesia. Causative or exacerbating factors

–Any CSM-like maneuver such as shaving, wearing tight collars, or turning one’s head sharply

–Neck tumors, extensive neck scarring secondary to radical dissection or radiation fibrosis, and neck trauma

–Certain medications can potentiate symptoms associated with CSH: Digoxin or β-blockers (especially with cardioinhibitory subtype)

Physostigmine, morphine, methacholine: increase vagal sensitivity and may predispose to cardioinhibitory subtype of CSH

PHYSICALEXAM

Normal unless carotid baroreceptor is stimulated, then

Bradycardia

Hypotension

Pallor

Diaphoresis

DIFFERENTIALDIAGNOSIS

Neurocardiogenic syncope

Postural hypotension

Situational syncope

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Postural tachycardia syndrome (POTS)

Primary autonomic insufficiency

Hypovolemia

Dysrhythmias

Sick sinus syndrome

Cerebrovascular insufficiency

Other causes of syncope (e.g., metabolic, psychogenic)

ECG may demonstrate sinus pause(s) or atrial-ventricular block.

Carotid duplex scan to rule out carotid stenosis in presence of a bruit (see the following section)

DIAGNOSTIC TESTS & INTERPRETATION

Diagnostic Procedures/Other

CSM is indicated in patients >40 years of age with syncope of unknown etiology after a negative initial evaluation (4)[B]. Commonly accepted technique for accurate diagnosis involves the following steps:

Patient in supine for 5 minutes with continuous BPmonitoring and ECG (on footplate-type tilt table for increased diagnostic accuracy); baseline BPand ECG are recorded.

For 5 to 10 seconds, apply firm longitudinal massage over the right carotid sinus (between the superior border of the thyroid and the angle of the mandible) at the site of maximal pulsation:

–Note that light pressure over the carotid sinus will not reliably produce a hypersensitivity response.

–Record symptoms, BP, and note ECG changes.

–Discontinue if asystole ≥3 seconds.

Positive response defined per criteria is listed above (asystole ≥3 seconds and/or drop in BP≥50 mm Hg), although specificity of the CSM technique increases if reproduction of a patient’s syncope is demonstrated during a test (4)[B]. If nondiagnostic, apply pressure to the left carotid sinus while the patient remains supine; if still nondiagnostic, repeat in 70-degree head-up tilt (first on the right then, if necessary, the left), allowing time for hemodynamic adjustment to the head-up position.

Evidence behind the testing strategy

–Right side first: Up to 66% with CSH have positive response on the right; if a positive right response, no need to repeat test on the left side

–30% of CSM exams are found to be nondiagnostic in the supine position but diagnostic in the 70-degree position (1).

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– Positive predictive value increases from 77% to 96% with a specificity of

93% by also performing CSM in 60to 70-degree tilt position (5). Absolute contraindications for CSM testing

–Carotid bruit present: must examine via carotid ultrasound with Doppler first:

No testing if >70% stenosis

Supine only testing if 50–70% stenosis

–Myocardial infarction, transient ischemic attack, or stroke within the past 3 months

Relative contraindications to CSM testing

–History of ventricular tachycardia or ventricular fibrillation

–False-positive results with CSM are relatively common in the elderly. Care

should be taken to exclude other causes of syncope.

Neurologic and cardiovascular complications have been reported during CSM. Cardiovascular complications (primarily arrhythmia) are extremely rare. Transient neurologic symptoms and signs occur in up to 0.9% of patients. Persistent neurologic deficits are extremely rare following CSM. Correctly performed CSM should be considered a safe, low-risk procedure (3)[C].

TREATMENT

GENERALMEASURES

No treatment is required for asymptomatic individuals.

High-dietary salt intake and increased fluid intake may be helpful to maintain intravascular volume in patients with vasodepressor subtype and absence of other cardiovascular disease.

MEDICATION

First Line

No single agent has demonstrated long-term effectiveness for treatment of recurrent and symptomatic CSH.

Second Line

Fludrocortisone or midodrine may be used to improve orthostatic symptoms in patients with vasodepressor subtype (not approved by FDAfor this indication). However, fludrocortisone causes sodium and water retention and should be used with caution in elderly patients with heart disease. An adverse

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effect with midodrine is that it increases mean ambulatory BP (3)[C].

Atropine may be used in the acute setting in patients with cardioinhibitory subtype with bradycardia.

Some evidence of benefit from sertraline and fluoxetine in patients unresponsive to pacemakers (3)[C]

SURGERY/OTHER PROCEDURES

Permanent pacing: treatment of choice for patients with cardioinhibitory and mixed type CSH with recurrent syncope; based on 2012 ACCF/AHA/HRS Focused Update Incorporated into the ACCF/AHA/HRS 2008 Guidelines for Device-Based Therapy in CSH (6)[C]:

–Class I indication: Permanent pacing is indicated for recurrent syncope caused by spontaneously occurring carotid sinus stimulation and carotid sinus pressure that induces ventricular asystole of >3 seconds.

–Class IIa indication: Permanent pacing is reasonable for syncope without clear, provocative events and with a hypersensitive cardioinhibitory response of 3 seconds or longer.

–Class IIb indication: Permanent pacing may be considered for significantly symptomatic neurocardiogenic syncope associated with bradycardia documented spontaneously or at the time of tilt-table testing.

–Class III indication: Permanent pacing is not indicated for a hypersensitive cardioinhibitory response to carotid sinus stimulation without symptoms or

with vague symptoms.

Permanent pacing may reduce the frequency of symptoms but may not completely eliminate them.

Surgery for patients with CSH secondary to mass effect from tumor burden Carotid sinus denervation by surgery or radiation therapy is no longer recommended because of the high rate of complications.

ONGOING CARE

PATIENT EDUCATION

Avoid precipitating maneuvers (as described above) that place pressure on the neck, such as tight collars and neckties.

With syncope, restrict driving or other potentially hazardous activities until the patient is cleared by the physician (4).

Avoid precipitating medications like vasodilators and those temporally related

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