UMEM Educational Pearls - Cardiology

Utility of Intra-Aortic Balloon Pump (IABP)

• IABP therapy has not been proven to reduce mortality in all-comers with cardiogenic shock complicating acute myocardial infarction (IABP-SHOCK II)
• A recent retrospective review of IABP therapy in patients with mechanical complications (ventricular septal rupture [VSR] or mitral regurgitation [MR]) following acute myocardial infarction has proven efficacious in this subset
• • IABP reduced mortality in patient with shock (61% vs 100%, p = 0.04)
  • IABP reduced preoperative mortality (11% vs 88%, p <0.001)
• Post infarction VSR or MR with signs of cardiogenic shock should be considered for an IABP as a bridge to emergent surgical repair
• Patients with mechanical complications without shock were not shown to benefit from an IABP and should undergo cardiac surgery after medical stabilization

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Watch this video to review Sgarbossa criteria and the modified Sgarbossa rule.

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Attachments

1311092043_American_Heart_Journal_2013_MD.pdf (726 Kb)

Secondary Prevention in AMI

Just as aspirin is pivotal in the treatment of acute coronary syndrome, medications such as beta-blocker, statins, and angiotensin-converting enzyme inhibitors have been proven to be essential in secondary prevention of AMI.

Patients after AMI are typically discharged on appropriate secondary prevention medications; however the prescribed doses are often far below the proven efficacy based on clinical trials.

A review of 6,748 patients from 31 hospitals enrolled in 2 U.S. registries (2003 to 2008) illustrated that only 1 in 3 patients were prescribed these medications at goal doses.

Of patients not discharged on goal doses, up-titration during follow-up occurred infrequently ~25%.

Optimal medication dosing and appropriate titration is integral to prevention of further morbidity and mortality.

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First-degree atrioventricular (AV) block is defined as an abnormally prolonged PR-interval >200ms. Although traditionally considered to be a benign clinical entity, not all first degree AV blocks are treated the same.  

Markedly prolonged PR-intervals (PR >300ms) can cause symptoms and hemodynamic compromise due to inadequate timing of atrial and ventricular contractions. Consider the following ECG from a 32 YOF with intermittent episodes of syncope and dizziness…

There is marked first degree AV block (PR=434 ms). When the PR-interval gets too long, AV dyssynchrony compromises ventricular filling and decreases cardiac output, similar to the so-called pacemaker syndrome.

Current ACC/AHA guidelines state that permanent pacemaker implantation is reasonable for marked first degree AV block with hemodynamic compromise or symptoms similar to those of pacemaker syndrome. (Class IIa, Level of Evidence B). The guidelines caution that pacemakers are not indicated in asymptomatic patients with isolated first degree AV block.

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Attachments

1310272020_ACC:AHA_Pacemaker_Guidelines.pdf (1,524 Kb)

1310272159_1st_Degree_AVB._Benign_or_Curable_Cardiac_Disease.pdf (247 Kb)

Ebstein's Anomaly

• Congenital defect of the tricuspid valve (TV) and the right ventricle (RV)
• TV septal and posterior leaflets are apically displaced resulting in "atrialization" of a portion of the right ventricle (ultimately a large right atrium and small right ventricle)
• ~40-50% of individuals with Ebstein anomaly have evidence of Wolf-Parkinson-White, secondary to the atrialized right ventricle
• ECG abnormalities include:
  • Right atrial enlargement or tall and broad P waves (Himalayan P waves) 
  • Prolonged PR interval
  • Right bundle branch block 
  • Low amplitude QRS complexes in the right precordial leads
  • T wave inversions V1-V4 and/or Q waves V1-V4

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Question

A 48 year-old female presents to the ED with progressive dyspnea and chest discomfort over the past 3 months. HR = 105, BP = 100/60 mmHg, with mild JVD on exam. Her ECG is shown below. What ECG abnormalites are present? What does your differential diagnosis include? What is the best initial diagnostic test?

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Attachments

1310132023_ECGs_with_small_QRS_voltages.pdf (578 Kb)

1310132023_Low_QRS_voltage_and_its_causes.pdf (108 Kb)

Acute Aortic Syndromes

Classically, aortic dissection is considered the primary culprit in patients with chest pain that radiates to the back (aortic pain) or chest pain combined with ischemia (cerebral, cardiac, peripheral), syncope, or cardiac arrest. However, it should not be your only concern: the rate of aortic rupture is much higher in penetrating atheromatous ulcer (42%) and intramural hematoma (35%) than in aortic dissection (types A 7.5% and type B 4.1%).

Chest pain with concomitant ischemic symptoms and acute decompensation should prompt consideration of several etiologies under the umbrella of aortic syndromes and not limited to dissection :

1. Penetrating atheromatous ulcer - rupture of an atheromatous plaque through the internal elastic lamina, with subsequent localized medial disruption and potential dissection, pseudoaneurysm formation, or free rupture
2. Intramural hematoma - rupture of the vasa vasorum or hemorrhage within an atherosclerotic plaque followed by aortic wall infarct
3. Aortic dissection- an intimal tear with resultant propagation within the middle third of the medial layer of the aorta
4. Aneurysm leak or rupture - progressive vessel dilation and increased wall tension
5. Traumatic transection - rapid deceleration forces or direct trauma, commonly shearing distal to left subclavian artery at aortic isthmus where the aorta is fixed by ligamentum arteriosum

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The primary goal in management of STEMI is rapid coronary revascularization. STEMI's are occasionally complicated by ventricular fibrillation (VF) arrest. High quality chest compressions and early defibrillation will improve survival. But what can be done in cases where conventional ACLS measures fail and patients have shock-refractory VF?

Some have suggested that emergent PCI with ongoing CPR en route may be beneficial. This option may be considered in close consultation with cardiology if the arrest is thought to be driven by ongoing ischemia and infarction. However, definitive data is lacking and this has only been described in a handful of case reports.

There may also be a role for venoarterial ECMO to aid in perfusion of vital organs and limit the risk of multisystem organ failure. The ECMO circuit can also help facilitate therapeutic hypothermia after the culprit vessel(s) is revascularized and rhythm is restored. 

Chances for survival are highest in younger patients, those that do not have chronic illnesses, and those who received immediate CPR after arrest. 

Summary:

Consider emergent consultation for salvage PCI and ECMO in select cases of shock-refractory ventricular fibrillation associated with STEMI

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Attachments

1309292147_NEJM-Refractory_VF_arrest.pdf (800 Kb)

Is RBBB More Indicative of Large Anteroseptal MI?

• Conventionally a new onset left bundle branch (LBBB) with acute myocardial infarction (MI) is associated with a massive MI
• Proximal left anterior descending artery (LAD) septal perforators perfuse the right bundle branch and the anterior fascicle of the left bundle branch ~90% of cases
• The right coronary artery (RCA) perfuses the posterior fascicle of the left bundle branch ~90% of cases
• Given the anatomy, a LAD occlusion should cause RBBB and/or LAFB; both a proximal LAD and RCA occlusion would be required for MI to cause LBBB
• A recent cohort study analyzed 233 patients to evaluate if RBBB or LBBB was associated with a large anteroseptal scar:
  • RBBB was associated with larger scar size (24% vs. 6.5%; p<0.0001)
  • RBBB was more indicative of ischemic heart disease (79% vs. 29%; p<0.0001)
• Based on this preliminary data RBBB may have a stronger association with ischemia and anteroseptal scarring than LBBB (*limitations - small cohort of cardiomyopathy patients with an EF<35%, further study is required)

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Colchicine is known to be effective in treatment of recurrent pericarditis, but until recently its efficacy during the first attack of acute pericarditis has been uncertain.

A recent multicenter, double-blinded, RCT of patients with acute pericarditis found colchicine to be effective in reducing the rate of incessant or recurrent pericarditis (primary outcome), as well as the rate of hospitalization. Here are some highlights:

•  240 patients with acute pericarditis received conventional therapy (aspirin or ibuprofen), half of them were randomized to also get colchicine, the other half to placebo for 3 months
• Incessant or recurrent pericarditis: 16%  in the colchicine group versus 37% in the control group (relative risk reduction=0.56; CI 0.30-0.72; NNT =4; p < 0.001)
• Symptom persistence at 72 hours, recurrences per patient, and hospitalization rate were all significantly reduced in the colchicine group
• There were no significant differences in adverse effects or discontinuation of the study drugs

Bottom-line:

Colchicine is a safe and effective drug for the treatment of acute pericarditis. Consider adding colchicine to conventional therapies to reduce duration of symptoms, recurrences, and rate of hospitalization.

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Attachments

1309151219_NEJM-Colchicine_RCT.pdf (527 Kb)

• In 1936 early repolarization (ER) was 1st described as ST-segment elevation in the absence of coronary artery disease, typically viewed as a benign ECG finding (BER) not association with increased cardiovascular mortality
• Classically the prevalence of BER tends to be associated with young athletes, male sex, and black race
• Recent data from Haissaguerre et al. and Tikkanen et al. suggest that certain subtypes of ER may be associated with a predisposition for malignant arrhythmias and sudden cardiac death (SCD)
• Although ER has various definitions contingent on the author, it consists of two components:
  • 1.) Prominent J wave
  • 2.) ST-segment elevation
• This article (9/13 JACC) focuses on the analysis and importance of the ST-segment contour and its possible relation to “malignant” repolarization
• Several studies (subgroup analysis) have found that a rapidly ascending ST-segment blending with the T-wave (Figures: A & C) confers BER, whereas a flat, horizontal, or even descending ST-segment (Figures: B & D) prior to the T-wave has potential to be malignant

*Please see the attachment below for Figures A-D

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Attachments

1309081121_gr1.jpg (74 Kb)

A recently revised ACEP clinical policy aims to guide emergency physicians in the evaluation and management of such patients.

They make the following recommendations (Level C):

• Routine screening tests (ie, CXR, ECG, UA, BMP) do not reduce adverse outcomes and are not required from the ED.
• Initiation of medical treatment does not reduce adverse outcomes and is not required in the ED.
• Patients with persistently elevated blood pressure should be referred for primary care follow-up.
• In select patient populations (eg. poor access to care), a screening creatinine level may identify renal injury that may alter disposition.
• If medication is started in the ED, the goal should be to facilitate gradual long-term control. Rapidly lowering blood pressure may be harmful.

Bottom-line:

There's little evidence to guide the decision of which patients with markedly elevated blood pressures to test or treat in the ED. This new clinical policy suggests that routine screening and treatment is not required. Asymptomatic patients should be referred for close follow-up, but consider a BMP in patients with poor follow up. 

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Attachments

1309011328_Ann_Emerg_Med_2013_Wolf.pdf (186 Kb)

• 1^st generation drug-eluting stents (DES) have been shown to reduce restenosis and target vessel revascularizations (TVR) compared with bare-metal stents (BMS) in patients with STEMI
• 1^st generation DES have also been associated with increased rates of very late stent thrombosis (ST), raising concerns over the safety of these devices in patients with STEMI, who compared to patients with stable coronary artery disease, have greater rates of ST due to heightened platelet activation and the presence of thrombus
• The most important finding in this study is the significantly reduced risk of 1-year cardiac death, MI, and ST with CoCr-EES (cobalt-chromium everolimus eluting stent) compared to BMS
• The observed reduction in MI, ST, and composite cardiac death rates with CoCr-EES compared to BMS is consistent with experimental data suggesting that stents covered by fluorinated polymers are less thrombogenic than even BMS

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• Classically MVP is considered a benign diagnosis associated w/palpitations, atypical chest pain, dyspnea, and carries a low risk of complications 
• A recent study investigated MVP and its association w/ventricular arrhythmias in a cohort of unexplained out-of-hospital cardiac arrest (OHCA)
• A small subset of patients w/MVP experienced life threatening arrhythmias coined "malignant" MVP
• Malignant MVP was most often associated w/female sex, bileaflet valve, and frequent complex ventricular ectopic activity

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Tight glycemic control (HbA1C<7%) has previously been recommended in CAD based on data from the United Kingdom Prospective Diabetes Study (UKPDS)

A recent study (JACC) evaluated the relationship between glycemic control, cardiovascular disease (CVD) risk, and all-cause mortality 

Patients with a mean HbA1C 7-7.4% were compared to those with mean HbA1C <6%; tight glycemic control had a 68% increased risk of CVD hospitalization

Lenient HbA1C>8.5% also had significantly higher risk

CVD risk and all-cause mortality is greater with both aggressive and lax glycemic control and the optimal reference range may lie between 7-7.4%

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• A recent meta–analysis of 12 studies (6,538 patients with 1,824 ROSC) assessed the quality of cardiopulmonary resuscitation (CPR) using either manual vs. mechanical (load-distributing or piston-driven) compressions in out-of-hospital cardiac arrest
• Compared w/manual CPR, load-distributing band CPR had significantly greater odds of ROSC (odds ratio, 1.62 and p<0.001)
• The treatment effect for piston-driven CPR was similar to manual CPR
• The difference in percentages of ROSC rates from CPR was 8.3% for load-distributing band CPR and 5.2% for piston-driven CPR
• Compared with manual CPR, combining both mechanical CPR devices produced a significant treatment effect in favor of higher odds of ROSC with mechanical CPR devices (odds ratio, 1.53 and p<0.001)

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Radiation therapy is frequently utilized in the management of numerous thoracic malignancies

Cardiovascular disease is now the leading cause of nonmalignancy death in radiation-treated cancer survivors

The spectrum of radiation-induced cardiac disease is broad

The relative risk of CAD, CHF, pericardial/valvular disease, and conduction abnormalities is particularly increased

Early identification of potential cardiac complications w/cardiac MR and echocardiography provides an opportunity for regular assessment and potentially improved long term mortality

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1. Typically the normal ECG shows progression of T-wave size across the precordial leads & the T-wave in V1 is inverted or flat
2. A large upright T-wave in V1 can be considered normal when there is high voltage/LVH or LBBB
3. A new upright T-wave in V1 can be indicative of significant atherosclerotic disease
4. If the T-wave in V1 is larger than the T-wave in V6 have a high suspicion for myocardial disease
5. A new tall upright T-wave in V1 has ~84% specificity for ischemic heart disease (Barthwal)

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• Statin therapy significantly reduces the risk for thrombotic events
• A recent study sought to determine the impact of short-term intensive statin therapy on intracoronary plaque lipid content
• 87 patients with multivessel CAD undergoing percutaneous coronary intervention and at least 1 other severely obstructive were randomized to intensive (rosuvastatin
  40 mg daily) or standard-of-care lipid-lowering therapy
• Upon follow-up, median reduction (95% confidence interval) was significantly greater in the intensive versus standard group ( p=0.01)
• Short-term intensive statin therapy in small trials reduces lipid content in obstructive lesions and further large studies with longer follow-up are warranted

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Bifascicular block

1. Right bundle branch block (RBBB) + left anterior fascicular block (LAFB) 
2. RBBB + left posterior fascicular block (LPFB)
3. Complete left bundle branch block (LBBB)

Incomplete Trifascicular block

1. Bifascicular block w/1^st degree AV block    *classically referred to as “trifascicular block”*
2. Bifascicular block w/2^nd degree AV block
3. Alternating LBBB + RBBB

Complete Trifascicular block

1. Bifascicular block w/3^rd degree AV block 

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