Dilated Cardiomyopathy


Article Author:
Hadi Mahmaljy


Article Editor:
Mayank Singhal


Editors In Chief:
Melissa Max
Danyae Lee
Manouchkathe Cassagnol


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Kyle Blair
Trevor Nezwek
Radia Jamil
Erin Hughes
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Navid Mahabadi
Hussain Sajjad
Steve Bhimji
Muhammad Hashmi
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Abbey Smiley
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beata Beatty
Daniyal Ameen
Altif Muneeb
Beenish Sohail
Nazia Sadiq
Hajira Basit
Phillip Hynes
Komal Shaheen
Sandeep Sekhon


Updated:
12/28/2018 6:53:59 PM

Introduction

Dilated Cardiomyopathy (DCM) is a disease of the heart muscle characterized by enlargement and dilation of one or both of the ventricles along with impaired contractility defined as left ventricular ejection fraction (LVEF) less than 40%. By definition, patients have systolic dysfunction and may or may not have overt symptoms of heart failure. This disease process can be classified as either primary or secondary DCM. Primary DCM is considered idiopathic and the diagnosis can only be made after excluding secondary causes.[1][2][3]

Etiology

The most common etiology of dilated cardiomyopathy (DCM) is idiopathic and without an identifiable cause. DCM can have a familial or genetic predisposition although these cases are usually classified under idiopathic if no clear genetic link is identified. DCM has been associated with mutations in genes for Desmin (cytoskeletal), Lamin C (nuclear membrane), or Myosin (contractile proteins). The secondary causes include infectious myocarditis (e.g., viral, Chagas disease, Lyme disease), ischemic disease, hypertension, medication-induced (e.g., Anthracyclines), alcohol abuse, human immunodeficiency virus (HIV), peripartum cardiomyopathy, or infiltrative disease. Ischemic cardiomyopathy caused by coronary artery disease (CAD) is the most common cause of congestive heart failure. However, ischemic cardiomyopathy is classified as its own disease entity and is only described as a cause of DCM in occult disease in patients without known CAD. Stress cardiomyopathy, also known as Takotsubo cardiomyopathy or Broken heart syndrome, is a relatively uncommon but increasingly reported cause. However, it is often classified as its own entity separate from primary DCM. It is characterized by transient ballooning of the left ventricular (LV) apex typically following a severe psychological or physiological stress that is believed to be secondary to intense catecholamine surge.[4]

Epidemiology

DCM is more commonly seen in men than in women. Its prevalence in the general population is estimated at 36 cases per 100,000. DCM accounts for 10,000 deaths and 46,000 hospitalizations in the United States annually. These figures may underestimate the true prevalence because many patients are asymptomatic and, therefore, undiagnosed despite LV dysfunction. [5][2]

Pathophysiology

Many cases of dilated cardiomyopathy (DCM) are due to idiopathic etiology. But, it also can arise from various myocardial insults. Enlargement of the ventricles can either be secondary to LV failure or secondary to a primary cardiomyopathic process and can be associated with both systolic and diastolic dysfunction. Reduction in systolic function is believed to be caused by myocardial remodeling that results in an increase in both end-systolic and end-diastolic volumes. Histologic examination or the myocardium typically shows nonspecific changes of fibrosis and hypertrophy. It also reveals myocardial injury with a marked infiltrate by inflammatory cells. [6]

History and Physical

The majority of cases of dilated cardiomyopathy (DCM) present between the ages of 20 and 60; however, DCM can be seen in children or the elderly. A large number of patients with DCM may have a long latent period where they are clinically asymptomatic. When symptoms do arise, they are the result of LV systolic dysfunction. In addition to a focused cardiac history and examination, a more thorough evaluation is recommended to identify any systemic disease or secondary causes. Classic symptoms include paroxysmal nocturnal dyspnea, orthopnea, leg swelling, and shortness of breath. Nonspecific symptoms of fatigue, malaise, and weakness also can be present. More severe cases can present with thromboembolic complications, conduction disturbances, arrhythmias or even sudden cardiac death. Physical examination findings are largely not specific to other causes of cardiomyopathy and consist of typical findings seen with congestive heart failure. Findings include crackles in the lung fields, elevated jugular venous pressures, peripheral edema, and an S3 gallop. Classically, the point of maximum impulse or PMI is displaced laterally. Tricuspid or mitral regurgitation murmurs are not uncommon as a result of ventricular enlargement and annular dilation.

Evaluation

An evaluation for secondary causes of dilated cardiomyopathy (DCM) always should be pursued prior to making the diagnosis of idiopathic DCM. Workup is focused on identifying any possible reversible causes. Recommended laboratory testing includes thyroid function tests, HIV serology, electrolytes, and iron studies (to rule out hemochromatosis). Urine toxicology screen and alcohol level can be checked when substance abuse is suspected. In certain familial cases, genetic testing should be considered. Serum B-type natriuretic peptide (BNP) levels may be obtained in cases where the diagnosis is unclear. Chest X-ray may show cardiomegaly and evidence of pulmonary effusions and venous congestion. Electrocardiogram (EKG) may show nonspecific ST segment and T wave abnormalities. Echocardiography is crucial in making the diagnosis of DCM and provides an objective assessment of ventricular size, function, and any associated valvular abnormalities. Echocardiography also can identify the presence of a mural thrombus. Coronary angiography should be performed in those without a known history of CAD to further define coronary anatomy and rule out occult ischemic disease as the cause of DCM. Very rarely, a myocardial biopsy is needed for evaluation of storage diseases or infiltrative causes when suspected. As mentioned, histologic findings of idiopathic DCM are nonspecific, and biopsy exposes patients to unnecessary risk.[7]

Treatment / Management

Besides treating any identifiable and reversible underlying causes, the management and treatment of Dilated Cardiomyopathy (DCM) are in concordance with the standard heart failure guidelines. In patients with an acute congestive heart failure exacerbation, intravenous loop diuretics are given to treat hypervolemia. Management of chronic and stable disease with oral diuretics often is needed to achieve a euvolemic state. Angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARB) have shown benefit in the treatment of heart failure with reduced ejection fraction and are recommended in patients with DCM. Aldosterone receptor blockade with spironolactone or eplerenone also is recommended in patients with New York Heart Association (NYHA) heart failure class II-IV and systolic dysfunction. Similarly, beta-blockade with carvedilol, bisoprolol, or long-acting metoprolol is recommended in all patients with heart failure with reduced ejection fraction without any contraindications. The addition of isosorbide dinitrate plus hydralazine also has shown to increase survival amongst those with advanced disease. Finally, patients with disease refractory to maximum medical therapy should be considered for cardiac transplantation and LVAD as a bridge or for "destination" therapy in those who are not candidates for transplantation. Implanted cardioverter defibrillators (ICD) for primary prevention of sudden cardiac death and cardiac resynchronization therapy (CRT) can be considered and are recommended by the heart failure guidelines.[8][9][10]

Differential Diagnosis

  • Cardiac tamponade
  • Acute pericarditis
  • Hypertrophic cardiomyopathy
  • Restrictive cardiomyopathy

Prognosis

Overall, the prognosis of patients with dilated cardiomyopathy is guarded. Most patients eventually end up with chronic heart failure. Many become candidates for a heart transplant or an assist device which also adds more morbidity. The progression to heart failure depends on the ejection fraction and cause of the disease. Almost 50% of patients are dead within 5 years. With optimal medical therapy, patients with mild CHF can have a reasonably good quality of life.

Complications

  • Congestive heart failure
  • Cerebrovascular accident
  • Valvular heart disease
  • Abnormal cardiac rhythms
  • Sudden cardiac death

Postoperative and Rehabilitation Care

All patients with dilated cardiomyopathy need intense education on the diet. Both salt and water restrictions are necessary to prevent symptoms. Patients should remain physically active or enroll in a cardiac rehab program. Regular cardiac rehabilitation can lower the mortality rate by 20%, relieve symptoms and reduce adverse cardiac events.

Consultations

  • Cardiac surgeon
  • Cardiologist
  • Critical care specialist
  • Dietitian

Deterrence and Patient Education

Patient education regarding medication compliance, dietary restrictions and regular follow-up, is critical for management of dilated cardiomyopathy.

Pearls and Other Issues

  1. Unlike the past when all patients with DCM were empirically treated with anticoagulation, today the guidelines recommend the use of anticoagulants only in patients with atrial fibrillation, prosthetic heart valves, or known mural thrombus.
  2. When there is progressive end-stage heart failure despite maximal medical therapy and the prognosis is deemed poor, one may consider a heart transplant.
  3. All patients with DCM must be educated on the disorder and the importance of dietary restrictions in sodium and water.
  4. Patients with DCM should be referred for cardiac rehabilitation as this has been shown to reduce all cause mortality by 20-30% over 5 years, including improvement in symptoms.

Enhancing Healthcare Team Outcomes

Dilated cardiomyopathy is a progressive heart disorder with no cure. Eventually, most patients progress to heart failure and close to 50% are dead within five years. Today many treatments have been devised for the treatment of dilated cardiomyopathy, but for most of them, there is a lack of evidence to support their use. There is no longer any question that this disorder is best managed by an interprofessional team that specializes in heart disease. The three single most important factors that determine the prognosis are 1) diet, 2) medication compliance, and 3) an exercise program. The disorder should be risk stratified and managed accordingly.[11][12]

A dietitian or a nurse is vital because one of the best ways to prevent progression to heart failure is by restricting fluid and salt intake. The family must be told to weigh the patient and offer foods that are low in salt. The pharmacist must ensure that the patient remains compliant with the medications. There is ample evidence indicating that participating in an exercise program can reduce symptoms and lower all-cause mortality. If the patient is deemed to be a candidate for a heart transplant, the heart transplant team should be consulted early on.

Outcomes

The outcomes of patients with dilated cardiomyopathy depend on the cause, ejection fraction, and comorbidity. At least 50% are dead within five years, and many others go on to develop heart failure. Despite many treatments available, the majority remain experimental. In view of the lack of data on treatments, it is imperative that the education of the patient and family be done to ensure that they comply with fluid and salt restriction. [13][14]


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Dilated Cardiomyopathy - Questions

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Which of the following medications has not shown any mortality benefit in the treatment of heart failure with reduced ejection fraction?



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Which of the following combinations of medications are used in an HIV patient with dilated cardiomyopathy?



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Which class of medication is notorious for causing dilated cardiomyopathy?



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A 68-year-old female with dilated cardiomyopathy presents with dyspnea, leg swelling, and fatigue. Her vital signs are blood pressure 115/75 mmHg, pulse 98 and regular, and respirations 26. The exam shows jugular venous distention, a holosystolic III/VI murmur at the apex, crackles at both lung bases, and 2+/4 pedal edema. An echocardiogram shows enlargement of all chambers, biventricular systolic dysfunction, moderate pulmonary hypertension, ejection fraction of 20%, and severe mitral regurgitation. After diuresis, what is the best therapy for this patient?



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Which of the following combinations of medications is most useful in improving cardiac function in dilated cardiomyopathy associated with HIV?



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Which of the following is most often associated with alcoholism?



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A 56-year-old female with presents to the emergency department with a 6-hour history of sub-sternal chest pain and shortness of breath. Two days earlier, her husband passed away from colon cancer. Cardiac examination shows a normal S1 and S2 without S3, S4, murmur, or rub. Lung examination is normal. Serum troponin T level is 1.5 ng/mL Electrocardiogram shows ST elevation in anterior leads. Transthoracic echocardiogram is perform revealing apical ballooning of the left ventricle.Cardiac Catheterization shows no significant coronary artery disease. What is the most accurate diagnosis?



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What is the most common cause of dilated cardiomyopathy (DCM)?



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A 45-year-old man with a history of dilated cardiomyopathy presents to the emergency department. His ejection fraction is still 15% despite maximum medical therapy for the last six months. His EKG shows no significant ST segment changes, pathologic Q waves, or T wave inversions. His QRS is 100. What is the appropriate next step in management?



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Dilated Cardiomyopathy - References

References

Hershberger RE,Morales A, Dilated Cardiomyopathy Overview null. 1993     [PubMed]
Stergiopoulos K,Lima FV, Peripartum cardiomyopathy-diagnosis, management, and long term implications. Trends in cardiovascular medicine. 2018 Aug 1     [PubMed]
Paldino A,De Angelis G,Merlo M,Gigli M,Dal Ferro M,Severini GM,Mestroni L,Sinagra G, Genetics of Dilated Cardiomyopathy: Clinical Implications. Current cardiology reports. 2018 Aug 13     [PubMed]
Vikhorev PG,Vikhoreva NN, Cardiomyopathies and Related Changes in Contractility of Human Heart Muscle. International journal of molecular sciences. 2018 Jul 31     [PubMed]
Masarone D,Kaski JP,Pacileo G,Elliott PM,Bossone E,Day SM,Limongelli G, Epidemiology and Clinical Aspects of Genetic Cardiomyopathies. Heart failure clinics. 2018 Apr     [PubMed]
Bakalakos A,Ritsatos K,Anastasakis A, Current perspectives on the diagnosis and management of dilated cardiomyopathy Beyond heart failure: a Cardiomyopathy Clinic Doctor's point of view. Hellenic journal of cardiology : HJC = Hellenike kardiologike epitheorese. 2018 May 25     [PubMed]
Palomer X,Pizarro-Delgado J,Vázquez-Carrera M, Emerging Actors in Diabetic Cardiomyopathy: Heartbreaker Biomarkers or Therapeutic Targets? Trends in pharmacological sciences. 2018 May     [PubMed]
Dainis AM,Ashley EA, Cardiovascular Precision Medicine in the Genomics Era. JACC. Basic to translational science. 2018 Apr     [PubMed]
Mu M,Majoni SW,Iyngkaran P,Haste M,Kangaharan N, Adherence to Treatment Guidelines in Heart Failure Patients in the Top End Region of Northern Territory. Heart, lung     [PubMed]
Bertini M,Balla C,Pavasini R,Boriani G, Efficacy of cardiac resynchronization therapy in patients with isolated ventricular noncompaction with dilated cardiomyopathy: a systematic review of the literature. Journal of cardiovascular medicine (Hagerstown, Md.). 2018 Jul     [PubMed]
Broch K,Murbræch K,Andreassen AK,Hopp E,Aakhus S,Gullestad L, Contemporary Outcome in Patients With Idiopathic Dilated Cardiomyopathy. The American journal of cardiology. 2015 Sep 15     [PubMed]
Caviedes Bottner P,Córdova Fernández T,Larraín Valenzuela M,Cruces Romero Presentación de Casos Clínicos P, Dilated cardiomyopathy and severe heart failure. An update for pediatricians. Archivos argentinos de pediatria. 2018 Jun 1     [PubMed]
Taylor MR,Carniel E,Mestroni L, Cardiomyopathy, familial dilated. Orphanet journal of rare diseases. 2006 Jul 13     [PubMed]
Halliday BP,Gulati A,Ali A,Newsome S,Lota A,Tayal U,Vassiliou VS,Arzanauskaite M,Izgi C,Krishnathasan K,Singhal A,Chiew K,Gregson J,Frenneaux MP,Cook SA,Pennell DJ,Collins P,Cleland JGF,Prasad SK, Sex- and age-based differences in the natural history and outcome of dilated cardiomyopathy. European journal of heart failure. 2018 Jun 3     [PubMed]

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