Mycoplasma pneumoniae is a common respiratory pathogen that may be associated with a variety of other complications, including erythema multiforme, meningitis, peripheral neuropathy, and hemolytic anemia. Myocarditis has also been previously described in association with infection with this organism, but the manifestations have been minor, both in the electrocardiographic change (nonspecific abnormalities of the ST-T wave) and in signs of cardiac dysfunction. In this communication, we present a patient who developed signs and symptoms of myocarditis during the course of infection withMycoplasma pneumoniae associated with severe hemolytic anemia.
A 49-year-old white woman was hospitalized for evaluation of increasing shortness of breath, a cough productive of moderate amounts of yellowish-brown sputum, and fever of four days’ duration. There was no prior history of cardiac disease.
On physical examination, the patient’s oral temperature was 39°C (102.2 F), the pulse was 132 beats per minute, the blood pressure was 150/80 mm Hg, and the respiration rate was 30/min. The veins in the neck were flat at 45° in the semirecumbent position. On auscultation of the chest, diffuse rhonchi and rales were heard bilaterally. A soft grade-1/6 systolic ejection murmur was heard along the left sternal border. The physical examination was otherwise unremarkable.
On admission, the hematocrit reading was 44 percent, and the white blood cell count (WBC) was 13,600/cu mm, with 68 percent polymorphonuclear cells and 20 percent band cells. The platelets were estimated to be normal. The serum electrolyte levels were as follows: sodium, 122 mEq/L; potassium, 3.8 mEq/L; and chloride, 89 mEq/L. Simultaneously determined urinary levels were sodium, 156 mEq/ L; potassium, 39 mEq/L; and urinary osmolality, 602 mOsm/ kg H2O. Arterial blood gas levels with the patient on a 10-L oxygen rebreathing made were as follows: pH, 7.35, carbon dioxide tension, 36 mm Hg; oxygen pressure, 56 mm Hg; and calculated carbon dioxide content, 21 mEq/L, with oxygen saturation of 87 percent. Initial titers of cold agglutinins were positive at a 1:8 dilution. The chest roentgenogram revealed bilateral basilar interstitial infiltrates, and die electrocardiogram exhibited sinus tachycardia with borderline first-degree atrioventricular block (Fig 1).
Because of a presumptive diagnosis of viral pneumonia with a possible superimposed bacterial infection, die patient was treated with cephazolin sodium (3 gm intravenously per day), methylprednisolone (60 mg/day), and oxygen therapy, which resulted in gradual improvement. On the sixth day of hospitalization, the therapy with cephazolin was discontinued, but the methylprednisolone dosage was maintained at 20 mg/day.
On the tenth day of hospitalization, die patient noted worsening of her shortness of breath and orthopnea. Physical examination now revealed a grade 3/6 pansystolic murmur at the lower left sternal border and apex, an S4 gallop rhythm, diffuse pulmonary rales, and distended neck veins without peripheral edema. The chest roentgenogram showed improvement of die interstitial infiltrate seen on admission but also showed borderline cardiomegaly. Over a period of 12 hours, the ECG evolved from a pattern of tachycardia with peaked T waves in the anterior precordial leads to changes consistent with an acute lateral-wall myocardial infarction (Fig 2). The hematocrit reading, which was 38 percent on the tenth day of hospitalization, fell to 25 percent over the next two days, with a WBC of 26,000/cu mm and a platelet count of 1,065,OOO/cu mm. Spherocytes and basophilia were noted on the peripheral blood smear. The reticulocyte count was 6.5 percent, and a small amount of urinary hemoglobin was detected. Titers for cold agglutinins were now positive at 1:4,096 at 4*C and at 1:256 at 37*C, with erythrocyte anti-I antibodies demonstrated. The direct Coombs’ test was positive to Сз complement. The serum iron level, the total iron-binding capacity, and the levels of folate and vitamin B12 were normal.
On the 11th day of hospitalization, the creatine phospho-kinase level, which was 48 units/L on admission, rose to 273 units/L (normal, 50 to 200 units/L). The lactic dehydrogenase level was 638 units/L (normal, 100 to 250 units/L); the level of serum glutamic transaminase was 46 units/L (normal, 3 to 23 units/L); and the level of serum glutamic pyruvic transaminase was 30 units/L (normal, 3 to 20 units/ L). Renal function remained normal.
The patient was given digoxin, and six units of warmed packed red blood cells were transfused to maintain the hematocrit reading at 30 percent. Five days after the apparent infarction, die ECG revealed only nonspecific T-wave changes, with resolution of the pattern of infarction (Fig 3). The patient improved without further complications and wasdischarged on the 22nd day of hospitalization.Two months after discharge, only nonspecific T-wave changes remained. The complement-fixation titer for Mycoplasma pneumoniae, which was negative on admission, rose to 1:64. Acute and convalescent serologic testing for adenovirus, influenzas A and B, psittacosis, respiratory syncytial virus, Q fever, herpes, and mumps showed no evidence erf recent infection from these organisms.
Figure 1. Admission ECG showing sinus tachycardia and borderline first-degree atrioventricular block.
Figure 2. ECG obtained on the tenth day of hospitalization, showing changes consistent with acute lateral-wall myocardial infarction.
Figure 3. ECG on 15th day of hospitalization, showing nonspecific T-wave changes and resolution of pattern of infarction.