Dressler syndrome (DS), also known as postmyocardial infarction syndrome, is a form of secondary pericarditis with or without a pericardial effusion, that occurs as a result of injury to the heart or pericardium. Though not a common condition, DS should be considered in all patients presenting with persistent malaise or fatigue, following a myocardial infarction (MI) or cardiac surgery, especially if symptoms present greater than two weeks following the event.
Pericarditis is a condition in which the pericardium (a fibroelastic sac surrounding the heart and comprised of a parietal and visceral layer which is separated by a potential space) becomes inflamed. Under normal circumstances, the pericardial cavity holds 15 to 50mL of pericardial fluid (an ultrafiltrate of plasma).
DS is part of a group of post-cardiac injury syndromes, which include postpericardiotomy syndrome and post-traumatic pericarditis (iatrogenic causes including percutaneous coronary or intracardiac interventions – pacemaker lead insertion, radiofrequency ablation and non-iatrogenic causes: blunt or penetrating trauma). Each represents a different clinical condition characterized by an initial cardiac injury involving the pericardium/myocardium and/or pleura and the subsequent inflammatory syndrome ranging from simple, uncomplicated pericarditis to more complicated cases with pleuropericarditis, cardiac tamponade, or massive pleural effusion.
The exact cause of DS is not known, though it is presumed that an initial injury to mesothelial pericardial cells combined with blood in the pericardial space triggers an immune response and results in immune complex deposition in the pericardium, pleura, and lungs which cause an inflammatory response.
This theory is supported by a number of observations regarding post-cardiac injury syndromes. There is often a distinct latency period observed at the time of cardiac injury and the development of a post-cardiac injury syndromes. In some instances, there is both a pleural effusion and/or a pulmonary infiltrate seen. Additionally, patients that have undergone cardiac surgery with subsequent post-cardiac injury syndrome often are found to have more elevated levels of anti-actin and actomyosin antibodies postoperatively. Finally, patients with DS or another post-cardiac injury syndrome tend to respond very well to anti-inflammatory treatments, and relapses are occasionally seen with withdrawal from steroids.
In the initial study examining DS in 1956, William Dressler suggested that the syndrome would occur in approximately 3% to 4% of patients with myocardial infarction (MI). With modern improvements in the management of acute myocardial infarctions, however, the condition is seen in much fewer patients. This may be attributable to successful interventions resulting in a reduction in the size of the infarct and subsequently damaged myocardium, thereby preventing the immune-mediated response seen in DS.
The risk of developing DS tends to be greater in post-MI patients who have suffered a larger infarction. Additionally, relapses are more likely to occur if a patient already has had a previous episode of DS. Additional predisposing factors for DS include viral infections, surgeries involving greater myocardial damage, younger age, prior history of pericarditis, prior treatment with prednisone, B negative blood type, and use of halothane anesthesia.
In terms of viral infections, a seasonal variation in the incidence of DS has been noted, where the condition is seen more commonly when the prevalence of a viral infection in the community is greatest too. Though elevated viral titers are found in patients experiencing associated DS, viral components have not been isolated from the pericardium itself or the pleural effusion of these patients.
Surgeries that result in greater damage to the myocardium (e.g., aortic valve replacement) are more likely to result in DS than those that cause less myocardial injury (e.g., mitral valve replacement). Though, it is important to note that DS can occur in patients that have undergone surgeries resulting in minimal trauma to the myocardium (e.g., needle puncture of a ventricle, CABG). Therefore, it is difficult to determine whether the extent of myocardial damage predicts the incidence of DS.
Finally, patients undergoing cardiac surgery that are younger, have a B negative blood type, or a prior history of pericarditis or treatment with prednisone should raise clinical suspicion as they have a greater risk of developing DS. Practitioners should be cautious to note early signs of the condition (e.g., chest pain, persistent de novo fever).
The exact cause of DS is unknown, though it is thought to be immune-mediated. Antimyocardial antibodies have been shown to be elevated in the blood of patients with DS, but it is unclear whether these antibodies are the cause or occur as a result of the syndrome. These antimyocardial antibodies are thought to target antigens that have become exposed through damage to the pericardium.
Viruses that have been associated with DS include coxsackie B, adenovirus, and cytomegalovirus – that these patients present with elevated levels of viral components.
Patients typically present with symptoms of DS 1 to 6 weeks following the initial damage to the pericardium. The most commonly encountered symptoms include fever, malaise, pleuritic chest pain, irritability, and decreased appetite. Occasionally, patients may present with dyspnea or arthralgias.
Though most patients tend to present with a temperature between 100.4 F and 102.2 F (measured orally), occasionally spiking as high as 104 F, not all patients will appear concomitantly ill, and the fever generally will subside within 2 to 3 weeks.
Children with DS may complain of chest pain that is worse with inspiration or while laying down. Emesis is often noted in children with DS that are at risk of impending cardiac tamponade.
On physical examination, patients with DS are often tachycardic with a pericardial friction rub heard on auscultation. This characteristic pericardial friction rub may disappear, however, both with improvement in or worsening of accumulation of pericardial fluid. Additionally, patients may present with pulsus paradoxicus (e.g., greater than the 10mmHg decrease in blood pressure with inspiration, and decreased pulse amplitude palpated on the radial artery).
Finally, some patients with DS may exhibit signs of pneumonitis (e.g., a cough, decreased oxygen saturation, fever).
The standard diagnostic procedure and most sensitive imaging study for evaluating a patient with suspected DS is an echocardiogram (echo). An echo will allow for evaluation of the pericardial fluid, if present, and help discern the exact cause of reduced cardiac output (i.e., determine whether truly DS or another condition such as congestive heart failure). An echo will further allow for evaluation of ventricular contractility, in addition to assessment of the potential risk of cardiac tamponade (i.e., if cardiac chambers appear compressed by pericardial fluid). The more pericardial fluid that is accumulated, the easier it is to detect its presence by echocardiography.
If it is difficult to assess the posterior pericardium with an echo, cardiac magnetic resonance imaging (MRI) may be employed to determine whether there is an effusion present. In some instances, fluid collections may also become loculated. This is also more readily visualized with cardiac MRI than with echo.
Chest radiography (x-ray) may be employed if echocardiography is not available. A chest x-ray will reveal flattening of the costophrenic angles and enlargement of the cardiac silhouette as a result of pleural effusion.
An electrocardiograph (ECG) in a patient with DS will initially demonstrate global ST segment elevation and T-wave inversion, such as with pericarditis. Further inflammation of the myocardium will also result in ST segment elevations. A low QRS also may be observed if there is a large volume pericardial effusion present.
Blood cultures should be obtained early in the workup of DS as this will help differentiate between an inflammatory versus an infectious cause of the patient’s condition. In the case of DS, blood cultures should be negative.
Laboratory studies that may help point toward a diagnosis of DS include an elevated white blood cell count (with a leftward shift) and elevated acute phase reactants (e.g., erythrocyte sedimentation rate and C-reactive protein). Additionally, there may be a high titer of anti-heart antibodies present in serology.
If it is possible, pericardial fluid (e.g., through a pericardial drain) should be examined for cell count, differential, cultures, Gram stain, cytology, total protein, and triglyceride levels.
Most patients with suspected DS are treated in an outpatient setting with close follow-up, unless the patient is hemodynamically unstable. The approach typically involves NSAIDs (e.g., aspirin, ibuprofen, naproxen) which are tapered over a period of 4 to 6 weeks as the accumulated pericardial fluid diminishes. Patients who do not respond to NSAID therapy may be given a 1-week course of corticosteroids (e.g., prednisone) which are tapered over a 4-week period.
More severe cases of DS (i.e., symptoms that may indicate imminent cardiac tamponade or constrictive pericarditis) may require inpatient care involving pericardial drainage. Pericardiocentesis with subsequent catheter drainage (generally 24 to 48 hours) and concomitant initiation of anti-inflammatory treatment are considered the standard of care for patients with a significant pericardial effusion. If the effusion is global (surrounding the entire heart) and visible anteriorly (in front of the right ventricle), the subxiphoid approach for pericardiocentesis is recommended in addition to echocardiographic guidance.
Once the pericardial fluid is drained and clinical symptoms have improved, however, most of these patients are also able to resume outpatient care.
Recurrence of post-pericardiotomy syndrome, including DS, is common and relapses have been reported up to 1 year following the initial event.