UMEM Educational Pearls - Cardiology

Coronary Subclavian Steal Syndrome

Coronary subclavian steal syndrome (CSSS) is defined as coronary ischemia resulting from the reversal of flow in an internal mammary arterial graft usually secondary to subclavian stenosis.

Angiographic subclavian stenosis is defined as greater than 50% narrowing or greater than 20mmHg pressure difference across a lesion.

CSSS occurs in up to 4.5% of patients with prior CABG & common in older individuals with existing peripheral vascular disease.

CSSS most commonly manifests as stable angina, but frequently presents as unstable angina, acute myocardial infarction, acute systolic heart failure or even cardiogenic shock.

Screening for subclavian stenosis prior to CABG w/bilateral noninvasive blood pressure assessment, and a 15 mmHg or greater discordance should elicit further imaging.

Percutaneous revascularization is the first-line therapy for CSSS and has excellent long-term outcomes. 

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Heart Failure & Pulmonary Hypertension (Part II)

- HFpEF-PH management guidelines recommend the treatment of symptoms of congestion and volume overload, targeting LV relaxation and co-morbidities; including the management of pulmonary congestion, ischemia, sleep apnea, atrial fibrillation, and diabetes.

- Both atrial/ventricular dysrhythmias contribute to the mortality associated with HF & control of particularly atrial fibrillation, is an essential part of the early pulmonary vascular remodeling process.

- Both endothelin receptor antagonists (ERA) and prostanoids have been effective for PAH & clinical trials utilizing these agents have also been attempted in treatment of PH due to left heart disease, but have proven to be either neutral or even detrimental.

- Selective dilation of the pulmonary vessels in patients with postcapillary PH, without simultaneously ensuring the unloading of the LV, can cause profound pulmonary venous congestion resulting in sudden pulmonary edema, which greatly increases the morbidity in patients with this form of PH.

- Currently, the most compelling published data for pharmacological treatment targeting PH in HFpEF involves phosphodiesterase (PDE) inhibitor sildenafil.

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Heart Failure & Pulmonary Hypertension (Part I)

~50% of patients with heart failure & preserved ejection fraction (HFpEF) develop pulmonary hypertension (PH)

HFpEF with PH portends reduced survival and increased hospitalization rates compared to those without PH

HFpEF-PH is often confused with idiopathic pulmonary hypertension (IPAH) given the similar hemodynamics; differentiating them is challenging and requires careful consideration of clinical, radiologic, and hemodynamic data





Clinical parameters:


Typically 3rd–5th decade

Typically 6th–8th decade

 Comorbidities (HTN, HLD, DM, CAD)



 Atrial arrhythmias



 Obstructive sleep apnea



Echocardiographic parameters:

 LA size/volume



 LV diastolic function

Normal to mildly abnormal

Moderate to severely abnormal

Hemodynamic parameters:

 Resting PAWP

Always <15 mmHg

May be < or >15 mmHg

 Response to volume

PAWP <15 mmHg (increase ≤5 mmHg)

PAWP >15 mmHg (increase >5 mmHg)

 Response to exercise

PAWP <15 mmHg (increase ≤5 mmHg)

PAWP >15 mmHg (increase >5 mmHg)

(Table reproduced from article)


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Cardiovascular Morbidity & Sleep Apnea

Obstructive sleep apnea (OSA) is characterized by sleep-related periodic breathing, upper-airway obstruction, sleep disruption, and hemodynamic perturbations

Epidemiological data shows a strong association between untreated OSA & cardiovascular morbidity/mortality

Two recent studies by Gottlieb et al. (1) & Chirinos et al. (2) elucidated two important explicit and complicit treatment considerations for OSA

(1) In moderate-to-severe obstructive sleep apnea, the use of CPAP alone during sleep may ameliorate systemic hypertension and cardiovascular risk, even in patients who do not have "subjective" sleepiness

(2) Weight loss combined with CPAP use may further decrease cardiovascular morbidity

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Category: Cardiology

Title: Kounis Syndrome (Part II)

Posted: 10/12/2014 by Semhar Tewelde, MD (Updated: 4/17/2024)
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Kounis Syndrome (Part II)

- KS can develop from multiple etiologies: hymenoptera, proteins, vasoactive amines, histamine, acetylcholine, multiple antibiotics, and various medical conditions (angioedema, serum sickness, asthma, stress-induced cardiomyopathy).

- Hypersensitivity myocarditis and KS are two cardiac entities of allergic etiology affecting the myocardium and coronary arteries, respectively. These two entities can mimic each other and can be clinical indistinguishable.

- Presence of eosinophil’s, atypical lymphocytes, and giant cells on myocardial biopsy suggests hypersensitivity myocarditis.

- There is evidence showing use of corticosteroids with vasospastic angina with evidence of allergy or the presence of symptoms refractory to high-dose vasodilators has been reported to resolve symptoms.


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Kounis Syndrome (Part I)

- Kounis & Zavras (1991) described the syndrome of allergic angina and allergic myocardial infarction, currently known as Kounis syndrome (KS). Braunwald (1998) noted vasospastic angina can be induced by allergic reactions, with mediators such as histamine and leukotrienes acting on coronary vascular smooth muscle.

- Two subtypes have been described: type I, occurring in patients without predisposing factors for CAD often caused by coronary artery spasm and type II, occurring with angiographic evidence of coronary disease when the allergic events induce plaque erosion or rupture.

- This syndrome has been reported in association with a variety of medical conditions, environmental exposures, and medication exposures. Entities such as Takotsubo cardiomyopathy, drug-eluted stent thrombosis, and coronary allograft vasculopathy also appear to be associated with this syndrome.

-  Clinical presentation includes: symptoms and signs of an allergic reaction and acute coronary syndrome: chest pain, dyspnea, faintness, nausea, vomiting, syncope, pruritus, urticaria, diaphoresis, pallor, palpitations, hypotension, and bradycardia. 

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Ventricular Arrhythmias Originating from the Moderator Band

- Ventricular arrhythmias originating from the moderator band (MB) often have a distinct morphology

- Typically MB arrhythmias have a left bundle branch block pattern, QRS with a late precordial transition (>V4), a rapid down stroke of the QRS in the precordial leads, and a left superior frontal plane axis

- MB arrhythmias are often associated with PVC-induced ventricular fibrillation

- Catheter ablation is quite effective at termination of the arrhythmias and facilitated with intracardiac echocardiography (ICE)

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Optimal Revascularization in Complex Coronary Artery Disease

- A multicenter trial 4,566 patients with NSTEMI, unstable angina, and multi-vessel coronary artery disease were enrolled comparing outcomes of cardiac stenting versus coronary artery bypass.

- Cardiac stenting was associated with improved outcomes and lower mortality in the following subgroups: age >65 years, women, unstable angina, TIMI score >4, and 2 vessel disease.

- Despite high clinical risk patients who underwent cardiac stenting compared to surgical revascularization did better in this prospective registry. 

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PARADIGM Shift in Heart Failure

- Angiotensin-converting enzymes inhibitors (ACE-I) are cornerstone for treatment of heart failure (HF) given the multiple trials which have shown their positive risk reduction in cardiovascular death.

- Studies looking at the effect of angiotensin-receptor blockers (ARBs) on mortality have been inconsistent; thus ARB's have been recommended as 2nd-line for those who have unacceptable side effects to ACE-I.

- A recent double-blinded RCT (PARADIGM-HF)  ~8400 patients with class II-IV HF w/ ejection fraction <40% were treated with enalapril (standard therapy) versus novel therapy with neprilysin (neutral endopeptidase) inhibitor combined with an ARB.

- Primary outcomes were death from cardiovascular causes and hospitalization for HF; The RCT was ceased early (~27 months) because of an overwhelming benefit with the new agent.

- At study closure death occurred 26.5% in the standard group versus 21.8% in the novel group. The risk of HF hospitalization was decreased 21% with novel therapy.

- In early studies the use of a neprilysin inhibitor combined with an ARB has shown superior effects to current standard therapy (ACE-I), however long-term effects of this novel therapy are yet to be determined. 

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Category: Cardiology

Title: Sick Sinus Syndrome

Keywords: Sick Sinus Syndrome (PubMed Search)

Posted: 8/31/2014 by Semhar Tewelde, MD
Click here to contact Semhar Tewelde, MD

Sick Sinus Syndrome

- Sick sinus syndrome (SSS) is a cardiac conduction disorder characterized by symptomatic dysfunction of the sinoatrial (SA) node.

- SSS usually manifests as sinus bradycardia, sinus arrest, or sinoatrial block, and is sometimes accompanied by supraventricular tachydysrhythmias.

- Symptoms of SSS include: syncope, dizziness, palpitations, exertional dyspnea, fatigability from chronotropic incompetence, heart failure, and angina.

- Clinically significant SSS typically requires pacemaker implantation. Approximately 30% to 50% of pacemaker implantation in the United States list SSS as the primary indication.

- 2 large, prospective cohorts with an average follow-up of 17 years, observed the incidence of SSS increases with age, does not differ between men and women, and is lower among blacks than whites.

- Risk factors for SSS included greater BMI & height, elevated NT-proBNP level & cystatin C level, longer QRS interval, lower heart rate, hypertension, and right bundle branch block.

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Category: Cardiology

Title: GRACE Score

Keywords: GRACE score (PubMed Search)

Posted: 8/24/2014 by Semhar Tewelde, MD (Updated: 4/17/2024)
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GRACE Score  

- The Global Registry of Acute Coronary Events (GRACE) is an international database tracking outcomes of patients presenting with acute coronary syndromes (ACS).

- GRACE score is calculated based on 8 variables: Age, HR, systolic BP, creatinine, killip class, ST-segment deviation on EKG, cardiac biomarkers, and cardiac arrest on admission.

- Several reports have shown that the GRACE score is a better predictor of clinical outcome (risk of death or the combined risk of death or myocardial infarction at 6 months) than the TIMI score.

- A recent study evaluated the relationship between GRACE score & severity of coronary artery disease (CAD) angiographically evaluated by Gensini score in patients with NSTE-MI.

- Results showed that the GRACE score has significant relation with the extent & severity of CAD as assessed by angiographic Gensini score.

- GRACE score was shown to be important both for determining the severity of the CAD and predicting death within 6 months of hospital discharge from NSTE-MI.


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Category: Cardiology

Title: Nonatherosclerotic Coronary Artery Disease

Keywords: Nonatherosclerotic Coronary Artery Disease (PubMed Search)

Posted: 8/17/2014 by Semhar Tewelde, MD (Updated: 4/17/2024)
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Nonatherosclerotic Coronary Artery Disease

- Nonatherosclerotic coronary artery disease (NACAD) is a term used to describe a category of diseases, which include: spontaneous coronary artery dissection (SCAD), coronary fibromuscular dysplasia (FMD), ectasia, vasculitis, embolism, vasospasm, or congenital anomaly.

- NACAD is an important cause of myocardial infarction (MI) in young women, but is often missed on coronary angiography.

- A small retrospective study of women <50 years of age with ACS found that 54.8% had normal arteries, 30.5% atherosclerotic heart disease (ACAD), 13% nonatherosclerotic coronary artery disease (NACAD), and 1.7% unclear etiology.

- NACAD accounted for 30% of MI’s with SCAD & Takotsubo cardiomyopathy accounting for the majority of cases. 

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- Toxic effects of tricyclic antidepressants (TCA) are result of the following 4 pharmacologic properties:

  1.  Inhibition of norepinephrine & serotonin reuptake --> resultant seizure

2.  Anticholinergic activity --> resultant altered mental status, tachycardia, mydriasis, ileus

3.  Direct alpha-adrenergic blockade --> resultant hypotension

4.  Cardiac myocyte sodium channel blockade --> resultant widened QRS

- A QRS interval greater than 100 milliseconds has ~30% chance of developing seizures and ~15% chance of developing a life-threatening cardiac arrhythmia.

- A QRS interval greater than 160 milliseconds increases the chance of ventricular arrhythmias to greater than 50%.

- Clinical pearl: A very wide complex ventricular rhythm, concomitant hypotension and/or seizure disorder is suspicious for toxic ingestion and standard ACLS algorithm will not suffice, treatment must address the underlying culprit (i.e. TCA --> Tx. fluids, vasopressors, sodium bicarbonate, and intravenous lipid emulsion).

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Advances in Hypertrophic Cardiomyopathy (HCM)

- HCM is a genetically transmitted autosomal dominant disorder with two variants: hypertrophic obstructive cardiomyopathy (HOCM), also known as idiopathic hypertrophic subaortic stenosis (IHSS) or asymmetric septal hypertrophy, and non-obstructive hypertrophic cardiomyopathy (HNCM), also known as Yamaguchi syndrome.

- The most serious complication of both variants of HCM is sudden cardiac death (SCD) and end-stage heart failure, which rapidly progresses to cardiac death after its occurrence.

- Beta-blockers (1st line) and non-dihydropyridine calcium channel blockers are effective at improving clinical symptoms (syncope, dyspnea, chest pain, and exertional intolerance, etc.) however neither alone nor combined halt the progressive LV remodeling and prevent end-stage heart failure.

- Cardiac transplantation is the only treatment available for end-stage heart failure, but must occur before the onset of pulmonary hypertension, kidney malfunction, and thromboembolism for success.

- Class Ia anti-arrhythmic, disopyramide has been shown to be effective for symptomatic improvement (NYHA classification), but does not improve overall LV function or hypertrophy.

- A recent study found that another class Ia anti-arrhythmic, cibenzoline has been shown not only to reduce symptoms, but also improved LV diastolic dysfunction and induced a regression of LV hypertrophy. In this study cibenzoline has halted the progression of HCM to end-stage heart failure. 

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Category: Cardiology

Title: HIV & Atherosclerosis

Posted: 7/27/2014 by Semhar Tewelde, MD (Updated: 4/17/2024)
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HIV & Atherosclerosis

Advances in antiretroviral treatment has increased the life expectancy of patients with HIV significantly, AIDS-related deaths have fallen by 30% since they peaked in 2005.

HIV infection predisposes to a chronic inflammatory and immunologic dysfunctional state, subsequent highly active antiretroviral treatment (HAART) results in metabolic changes and dyslipidemia.

In the post-HAART era, CAD is now considered to be the main cause of heart failure in HIV-infected patients, superseding the prior most common etiologies myocarditis and opportunistic infections.

The presentation of CAD in HIV-infected patients is largely similar to that in the general population with the exception is that they present at a younger age.

Certain antiretroviral agents specifically protease inhibitors have conventionally been associated with lipid dysfunction, further complicating the HIV-infected patients milieu.

Recent research has shown that a C-C chemokine receptor-type 5 (CCR5) antagonists has emerged as a potential target both as an antiretroviral agent as well as in the process of arresting atherogenesis, but warrants more research.


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ECG Risk Predication in ARVD

Arrhythmogenic right ventricular dysplasia (ARVD) is a genetically determined cardiomyopathy characterized by fibrofatty replacement of the right ventricle (RV) predisposing to ventricular arrhythmias, heart failure, and sudden cardiac death (SCD).

Twelve-lead electrocardiography (ECG) is an easily obtainable and noninvasive risk stratification tool for major adverse cardiac event (MACE); defined as a composite of cardiac death, heart transplantation, survived sudden cardiac death, ventricular fibrillation, sustained ventricular tachycardia, or arrhythmic syncope.

ARVD ECG findings that predict adverse outcome are not well known.

A multicenter, observational, long-term study, found ECG findings were quite useful for risk stratification of MACE, specifically:

-       Repolarization criteria

-       Inferior leads T wave inversions

-       Precordial QRS amplitude ratio of ≤0.48

-       QRS fragmentation 

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Category: Cardiology

Title: Ventricular Arrhythmias Associated with Myocardial Infarction

Keywords: Ventricular Arrhythmias, Myocardial Infarction (PubMed Search)

Posted: 7/13/2014 by Semhar Tewelde, MD (Updated: 4/17/2024)
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Ventricular Arrhythmias Associated with Myocardial Infarction

Therapeutic advances and management of acute myocardial infarction (AMI) has lead to a decreasing incidence of ventricular arrhythmias (VA)

VA remains a life-threatening occurrence after AMI, and all patients should be monitored closely during this vulnerable period

VA occurs more frequently inpatients with STEMI versus non-STEMI

Of those who develop VA’s, features associated with poor outcomes include:

·      Late occurrence

·      Sustained monomorphic VT

·      Concurrent heart failure

·      Cardiogenic shock

·      Failure or lack of revascularization


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Category: Cardiology

Title: Role of Magnesium in Cardiovascular Disease

Keywords: Magnesium, cardiovascular disease, arrhythmia (PubMed Search)

Posted: 7/6/2014 by Semhar Tewelde, MD
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Role of Magnesium in Cardiovascular Disease

* Magnesium (Mg2+) is an essential element that is obtained via dietary intake of leafy green vegetables, legumes, nuts/seeds, and whole grains; it is relatively deficient in the American diet.

* Mg2+ is critical for the normal physiological functioning of the vascular smooth muscle, endothelial cells, and myocardium. Several epidemiological and clinical studies have linked Mg2+ in the pathogenesis of cardiovascular disorders (CVD).

* Mg2+ is well known for its antiarrhythmic properties via modulation of myocardial excitability and in the pathogenesis and treatment of cardiac arrhythmias (polymorphic ventricular tachycardia/torsades de pointes & digoxin toxicity).

* Mg2+ supplementation has also been shown to cause significant decrease in ventricular ectopic beats and nonsustained ventricular tachycardia in NYHA class II–IV heart failure patients.

* A recent meta-analysis by Qu et al examined the association between dietary Mg2+ intake, serum Mg2+ levels, and the risk of total CVD events; the greatest reduction in CVD events was observed for intake between 150-400 mg/d.

* Given the magnitude of CVD and Mg2+-deficient diet in the US, there is a critical need to further investigate the interrelationship between Mg2+ and CVD events. Additionally increasing Mg2+ intake in the diet to maintain high normal serum Mg2+ level is both physiologic and judicious.


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Category: Cardiology

Title: IVUS Plaque Correlation to Cardiovascular Death

Keywords: IVUS, CAD, vulnerable plaques (PubMed Search)

Posted: 6/29/2014 by Semhar Tewelde, MD (Updated: 4/17/2024)
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IVUS Plaque Correlation to Cardiovascular Death 

Several non-invasive studies are currently utilized for the identification of coronary artery disease  (i.e. coronary CTA, intravascular ultrasound- IVUS, etc.)

Few studies have quantified which of those with CAD (i.e. coronary plaques) are considered high-risk or unstable plaques

A recent study utilizing IVUS looked at autopsies over a 2 year-period comparing near-infrared detection of high-risk plaques and cardiovascular related deaths

IVUS findings associated with CAD are classified into 3 categories: echo-attenuation, echolucent zone, and spotty calcification

Echo-attenuated plaques, especially superficial echo-attenuation, was found to be a significant and reliable finding suggestive of vulnerable plaques and future cardiovascular death 

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Category: Cardiology

Title: Brain-heart crosstalk

Keywords: Brain-heart syndrome, Neurogenic Stress Cardiomyopathy (PubMed Search)

Posted: 4/27/2014 by Ali Farzad, MD
Click here to contact Ali Farzad, MD

“Brain-heart crosstalk” is being increasingly recognized in the acute phase after severe brain injury. Neurogenic stunned myocardium, also called ‘neurogenic stress cardiomyopathy’ (NSC), is a syndrome that can occur after severe acute neurologic injury (i.e. SAH, TBI, ischemic or hemorrhagic stroke, CNS infections, epilepsy, or any sudden stressful neurologic event). 
NSC is part of the stress-related cardiomyopathy syndrome spectrum, which includes Takotsubo syndrome. However, NSC refers specifically to myocardial dysfunction related to stress from catacholamine excess triggered by neurological injury, rather than emotional or physical stress. Neurocardiogenic injury from NSC is associated with an increased risk of all-cause mortality, cardiac mortality and heart failure.
Cardiac involvement can be appreciated with ECG changes and echocardiography. ECG changes include QT interval prolongation (large T waves & U waves), long QT syndrome & torsade de points, ST-segment depression, T-wave inversion, and ventricular & supraventricular arrhythmias. Importantly, NSC can also mimic acute myocardial infarction with LV wall motion abnormalities, and elevated cardiac biomarkers/BNP
Emergency physicians should be aware of the diagnostic challenges posed by NSC, and maintain a high index of suspicion when admitting a patient with an unclear clinical picture. NSC management is mainly supportive and symptomatic, based on treatment of life threatening events (i.e. malignant arrhythmias or cardiogenic shock). See references to learn more about the pathophysiology and treatment options.

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