17: Restrictive cardiomyopathy

CHAPTER 17
Restrictive cardiomyopathy


David P. McLaughlin and George A. Stouffer


Restrictive cardiomyopathy is a disease of the myocardium characterized by impaired relaxation and diastolic dysfunction of either or both ventricles. The disease is progressive and as the ventricles become less distensible, diastolic filling and cardiac output are impaired and filling pressures increase. A reduction in systolic function may also occur as the disease progresses. Initial symptoms are usually low output–type complaints (e.g., exertional dyspnea or exercise intolerance) because of inability to augment stroke volume. As right atrial (RA) pressure increases, symptoms of systemic venous congestion may predominate. Further increases in RA and pulmonary capillary wedge (PCW) pressures will be accompanied by symptoms of orthopnea and paroxysmal nocturnal dyspnea. The clinical presentation of restrictive cardiomyopathy can be similar to constrictive pericarditis and differentiation of these processes can be difficult. Additionally, some disease processes (e.g., amyloid) can involve both myocardium and pericardium, leading to a mixed hemodynamic profile.


Causes of restrictive cardiomyopathy include amyloidosis, hemochromocytosis, metabolic storage diseases, hypereosinophilic syndrome, metastatic malignancies, sarcoid, carcinoid, idiopathic, endomyocardial fibrosis, and mediastinal radiation.


Hemodynamic principles


The hemodynamic findings of restrictive cardiomyopathy and constrictive pericarditis are similar. Chapter 18 contains a more detailed description of the findings in constrictive pericarditis.



  1. Diastolic filling is impaired and determined by the degree of restriction.

    • Pressures during diastole are elevated and similar in all cardiac chambers. Right and left ventricular diastolic pressures are elevated and equal in early diastole, but generally end‐diastolic pressures differ by more than 5 mm Hg; in contrast to constrictive pericarditis, where left ventricular end‐diastolic pressure (LVEDP) and right ventricular end‐diastolic pressure (RVEDP) will be similar.
    • The difference between LVEDP and RVEDP is accentuated by exercise.
    • Stroke volume is decreased. Cardiac output will fall in the absence of tachycardia.
    • Severe pulmonary hypertension is more common than in constrictive pericarditis. RV and pulmonary systolic pressures may exceed 50 mm Hg.
    • Pulsus paradoxus is not found in restrictive cardiomyopathy because of a stiff, noncompliant septum.

  2. Almost all ventricular filling occurs in early diastole.

    • Exaggerated Y descent in atrial tracings (Figure 17.1).
    • Usual respiratory variation of atrial pressures is reduced, but the Y descent may become deeper during inspiration.
    • RA tracing may have a classic M or W configuration.
    • Dip and plateau configuration in RV and LV tracings.
2 ECGs of pressure tracings from a patient with amyloidosis displaying right atrial pressure (top) and left ventricular pressure and right ventricular pressure (bottom).

Figure 17.1 Pressure tracings from a patient with amyloidosis. Note the elevated RA pressures with an exaggerated Y descent (a). Simultaneous RV and LV pressures shows equalization during diastole (most notable during expiration) and concordance in which RV and LV systolic pressures both decrease with inspiration (b).


Differentiating restrictive cardiomyopathy from constrictive pericarditis


The hemodynamic effects of restrictive cardiomyopathy are similar to those of constrictive pericarditis, and it is generally difficult to make a correct diagnosis based on hemodynamics alone. Hemodynamic criteria that favor restrictive cardiomyopathy include:



  • Equalization of left and right ventricular filling pressures, but with a difference of more than 5 mm Hg between LVEDP and RVEDP. Remember that the studies from which the 5 mm Hg cutoff was determined were generally performed with high‐fidelity manometric catheters.
  • RVEDP does not exceed one‐third of the level of the right ventricular systolic pressure.
  • RV systolic pressure may be greater than 50 mm Hg.
  • Concordance, defined as an inspiratory decrease in both RV and LV systolic pressures during normal respiration (Figure 17.1). This is in contrast to discordance, which is an increase in RV systolic pressure simultaneous with a decrease in LV systolic pressure (seen in constrictive pericarditis). The difference in ventricular interdependence is due to the effects of respiration on ventricular filling. It is imperative to record RV and LV simultaneously on a 200 mm Hg scale on slow sweep speed and to assess several respiratory cycles.

A review of 82 cases of constrictive pericarditis and 37 cases of restrictive cardiomyopathy found that the predictive accuracy of a difference between RVEDP and LVEDP >5 mm Hg was 85%, the predictive accuracy of RV systolic pressure >50 mm Hg was 70%, and the predictive accuracy of a ratio of RVEDP to RV systolic pressure of less than 0.33 was 76%. If all three criteria were concordant, the probability of having classified the patient correctly was greater than 90%. However, one‐fourth of patients could not be classified by hemodynamic criteria [1].


A more detailed description of hemodynamic findings that can be used to differentiate restrictive cardiomyopathy from constrictive pericarditis can be found in Chapter 18.


Echocardiography


The ventricles are usually normal in size. LV hypertrophy is frequently present (of note is that decreased R wave amplitude on ECG coupled with LV hypertrophy on echo is frequently a clue to restrictive cardiomyopathies). Mitral inflow velocity in restrictive cardiomyopathy is typically one of a prominent E wave, decreased A wave, an increased ratio of early diastolic filling to atrial filling (>2), decreased deceleration time (<150 ms), and a decreased isovolumic relaxation time (<70 ms). Cardiac valves may be involved in restrictive cardiomyopathy, leading to regurgitation.


Respiratory variation in mitral valve inflow is less in restrictive cardiomyopathy compared to constrictive pericarditis. An echocardiographic study of 30 patients (19 with constrictive pericarditis and 11 with restrictive cardiomyopathy) found that significant respiratory variation in the ventricular inflow peak velocity ≥10% predicted constrictive pericarditis with a sensitivity and specificity of 84% and 91%, respectively [2]. Remember that mitral valve inflow velocity is dependent on preload and that marked elevation in LA pressure may mask respiratory variation [3]. Reducing preload (e.g., by head‐up tilting) may accentuate respiratory variation in inflow velocity.

Apr 25, 2017 | Posted by in CARDIOLOGY | Comments Off on 17: Restrictive cardiomyopathy
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