Cardiomegaly means enlargement of the heart. The definition is when the transverse diameter of the cardiac silhouette is greater than or equal to 50% of the transverse diameter of the chest (increased cardiothoracic ratio) on a posterior-anterior projection of a chest radiograph or a computed tomography. It should not be confused with an enlargement of the cardiomediastinal outline. Cardiomegaly is usually a manifestation of another pathologic process and presents with several forms of primary or acquired cardiomyopathies. It may involve enlargement of the right, left, or both ventricles or the atria.
Enlargement of the heart both in the form of dilatation or hypertrophy leads to a spectrum of clinical heart failure syndrome, with a prevalence of nearly 5.8 million people in the United States. Heart failure with preserved Ejection Fraction (HFpEF) represents more than half of these cases. The incidence of heart failure increases with age, male gender, and African American race. About half of the people diagnosed with heart failure die within 5 years of diagnosis.
The development of cardiac remodeling and hypertrophy is complex with genetic and non-genetic components. The most critical pathophysiological changes leading to cardiomegaly include dilated hypertrophy, fibrosis, and contractile malfunction. Contractile dysfunction and abnormal myocardial remodeling can lead to hypertrophic cardiomyopathy or dilated cardiomyopathy. Mechanical stretching, circulating neurohormones and oxidative stress are significant stimuli for the signal transduction of inflammatory cytokines and MAP kinase in cardiomyocytes. Signal transduction leads to changes in structural proteins and proteins that regulate excitation-contraction. Dilated cardiomyopathy mutations result in a reduced force of the sarcomere contraction and a reduction in sarcomere content. Hypertrophic cardiomyopathy mutations result in a molecular phenotype of hyperdynamic contractility, poor relaxation, and increased energy consumption.
Many patients with cardiomegaly are asymptomatic, and the presence of symptoms alone is neither sensitive nor specific to diagnosis. The diagnosis of cardiomegaly has its basis on imaging, and history is only helpful to determine the cause of heart failure symptoms which results in systemic congestion and impaired organ perfusion.
A detailed history should elicit the presence or absence of:
It is worth mentioning that cardiac function is adequate during rest may become inadequate with exertion. Hence it is not at all uncommon for patients to be asymptomatic at rest and experience symptoms on exertion only. The New York Heart Association classifies the severity of disease based on symptoms where class I disease is asymptomatic with ordinary physical activity and class IV denotes symptoms with rest.
Perhaps the most specific sign of cardiomegaly is a displaced point of maximal impulse (PMI). The precordial examination will reveal a displaced PMI usually below the 5th intercostal space and lateral to the midclavicular line and palpable across 2 intercostal spaces. Sustained PMI is a sign of severe left ventricular hypertrophy. A sustained and prolonged left parasternal heave is indicative of right ventricular hypertrophy. Another physical finding observed in cardiomegaly is the holosystolic murmur of mitral and/or tricuspid regurgitation resulting from dilatation of the mitral annulus and displacement of papillary muscles with abnormal myocardial remodeling. Other exam findings may be seen depending on the presence of decompensated heart failure. In such cases, a detailed physical exam may reveal the following abnormalities:
Diagnosis of cardiomegaly is primarily through imaging techniques that provide an assessment of the size and function of the heart. Diagnostic testing includes one of the following:
Treatment of mild cardiomegaly centers upon the treatment of the underlying condition. In moderate to severe cardiomegaly associated with heart failure, standard HF treatment guidelines also apply.
Of special consideration, no pharmacologic agent has shown benefit in HFpEF, and the mainstay of treatment is controlling underlying conditions such as hypertension, heart rate in patients with atrial fibrillation, ischemia with medication and/or coronary intervention, and diuretics for fluid overload. Patients with HOCM (hypertrophic obstructive cardiomyopathy) who are asymptomatic can be safely monitored. Patients who have symptoms of HF and left ventricular outflow tract obstruction, they may get benefit from negative inotropes such as beta blocker, calcium channel blocker or dipyridamole. Vasodilators and diuretics should be avoided in such patients.
Differentials of cardiomegaly include disorders that can result in an enlarged cardiomediastinal silhouette on a frontal (or posteroanterior) chest X-ray. These include:
Despite the advent of new therapies, mortality remains high in patients with symptomatic HF. Roughly, 1-year mortality is 30% while 5-year mortality is 50%. The severity of symptoms, advanced age, and HF hospitalization are significant predictors of mortality in HF.
Cardiac transplantation is an emerging treatment for patients with refractory end-stage heart failure. Patients undergo cardiopulmonary assessment and prognostication using specific scoring systems to determine their candidacy for transplant. Patients with systemic illness, life expectancy under 2 years, active substance and alcohol abuse, and non-compliance with medical therapy are considered poor candidates for cardiac transplantation. Patients should have a robust psychosocial support system to qualify. Ultimately, a risk-benefit assessment is necessary before the patient is a candidate for the transplant list. Patients who are not candidates for a cardiac transplant can qualify for a durable ventricular assist device.
Heart failure readmissions account for a majority of national healthcare expenditures. Support programs are operating nationwide to minimize the number of CHF related hospitalizations and thereby reduce the economic strain. These programs utilize a collaborative approach with many integrated disciplines and providers. Some of the inpatient strategies include guideline-based care, discharge support by nurses, patient education, medication reconciliation by the pharmacist, and early post-discharge follow up. Promising outpatient strategies include multidisciplinary HF clinics and disease management programs that make in-person contact with patients and providing individualized education.
Cardiomegaly and HF require an interprofessional team approach that includes physicians and specialists, specialty-trained nurses, and pharmacists and therapists, all working collaboratively to bring about optimal therapeutic choices leading to the best possible patient outcomes. [Level V]
|||Felker GM,Thompson RE,Hare JM,Hruban RH,Clemetson DE,Howard DL,Baughman KL,Kasper EK, Underlying causes and long-term survival in patients with initially unexplained cardiomyopathy. The New England journal of medicine. 2000 Apr 13; [PubMed PMID: 10760308]|
|||Goff ZD,Calkins H, Sudden death related cardiomyopathies - hypertrophic cardiomyopathy. Progress in cardiovascular diseases. 2019 Apr 17; [PubMed PMID: 31004609]|
|||Vischer AS,Castelletti S,Syrris P,McKenna WJ,Pantazis A, Heart failure in patients with arrhythmogenic right ventricular cardiomyopathy: Genetic characteristics. International journal of cardiology. 2019 Jan 27; [PubMed PMID: 30765282]|
|||Bui AL,Horwich TB,Fonarow GC, Epidemiology and risk profile of heart failure. Nature reviews. Cardiology. 2011 Jan; [PubMed PMID: 21060326]|
|||Garfinkel AC,Seidman JG,Seidman CE, Genetic Pathogenesis of Hypertrophic and Dilated Cardiomyopathy. Heart failure clinics. 2018 Apr; [PubMed PMID: 29525643]|
|||Rababa'h AM,Guillory AN,Mustafa R,Hijjawi T, Oxidative Stress and Cardiac Remodeling: An Updated Edge. Current cardiology reviews. 2018 Mar 14; [PubMed PMID: 29332590]|
|||Rocklin DM, The Role of the Clinical Examination in Patients With Heart Failure: E-Z CVP. JACC. Heart failure. 2018 Nov; [PubMed PMID: 30384921]|
|||Yancy CW,Jessup M,Bozkurt B,Butler J,Casey DE Jr,Colvin MM,Drazner MH,Filippatos G,Fonarow GC,Givertz MM,Hollenberg SM,Lindenfeld J,Masoudi FA,McBride PE,Peterson PN,Stevenson LW,Westlake C, 2016 ACC/AHA/HFSA Focused Update on New Pharmacological Therapy for Heart Failure: An Update of the 2013 ACCF/AHA Guideline 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. 2016 Sep 27; [PubMed PMID: 27208050]|
|||Ho KK,Pinsky JL,Kannel WB,Levy D, The epidemiology of heart failure: the Framingham Study. Journal of the American College of Cardiology. 1993 Oct; [PubMed PMID: 8376698]|
|||Mehra MR,Canter CE,Hannan MM,Semigran MJ,Uber PA,Baran DA,Danziger-Isakov L,Kirklin JK,Kirk R,Kushwaha SS,Lund LH,Potena L,Ross HJ,Taylor DO,Verschuuren EA,Zuckermann A, The 2016 International Society for Heart Lung Transplantation listing criteria for heart transplantation: A 10-year update. The Journal of heart and lung transplantation : the official publication of the International Society for Heart Transplantation. 2016 Jan; [PubMed PMID: 26776864]|
|||Feltner C,Jones CD,Cené CW,Zheng ZJ,Sueta CA,Coker-Schwimmer EJ,Arvanitis M,Lohr KN,Middleton JC,Jonas DE, Transitional care interventions to prevent readmissions for persons with heart failure: a systematic review and meta-analysis. Annals of internal medicine. 2014 Jun 3; [PubMed PMID: 24862840]|