Myocardial inflammation in polymyalgia rheumatica assessed using cardiac magnetic resonance imaging

A 66-year-old woman with a two-year history of subacute neck, shoulder and hip stiffness was referred to our department for further evaluation and follow-up. She had been intermittently treated with oral steroids (up to 15 mg per day) with recurrence of symptoms on discontinuation. During the past 1.5 years, she had also experienced episodes of tachycardia, which were treated with β-blockers. She had no risk factors for coronary artery disease and denied smoking or alcohol consumption. A physical examination revealed muscle tenderness in the shoulder girdle and hips with no lymphadenopathy or organomegaly. Electrocardiography revealed a sinus rhythm with 90 beats/min and nonspecific ST alterations in leads V2 to V6. Laboratory testing revealed low hemoglobin, elevated white blood cell and platelet counts, high erythrocyte sedimentation rate (78 mm/h), high C-reactive protein level (6 mg/L), and normal serum creatine kinase-MB and cardiac troponin T levels. Test results for thyroid, renal and hepatic function as well as urinalysis were normal. Autoantibody profile and opthalmological examination were negative. With a presumed diagnosis of polymyalgia rheumatica (PMR), treatment with steroids (15 mg once per day) was initiated, with rapid resolution of clinical symptoms and inflammatory markers. Two months later, slow steroid tapering was started. Due to the persistence of tachycardic episodes, she was referred to the cardiology department for further investigation.

The echocardiogram revealed diffuse left ventricular (LV) hypokinesia and deterioration of LV systolic function with a LV ejection fraction (LVEF) of 40%. The x-ray coronary angiography identified normal coronary arteries. To evaluate the possibility of myocardial inflammation during the course of PMR, cardiac magnetic resonance imaging (CMR) was performed using T2-weighted short-tau inversion recovery and T1-weighted multislice spin-echo images (before and after an intravenous bolus of 0.1 mmol/kg gadolinium Gd-DTPA). Measurements were performed within 1 min of Gd-DTPA infusion for assessment of early gadolinium enhancement (EGE). Immediately after the second set of T1-weighted images, 0.1 mmol/kg Gd-DTPA was readministered and late gadolinium enhancement (LGE) images were obtained 15 min later, using an inversion recovery sequence. The evaluation of images was performed as previously described (1).

Image analysis revealed a diffusely increased T2 ratio of myocardial to skeletal muscle signal (2.5; normal value <2) implying the presence of myocardial edema. While EGE is considered to be unreliable as a cardiac inflammatory index, in the presence of concomitant muscular inflammation, the evaluation of T1 images before and after gadolinium infusion identified a diffuse increase of myocardial signal intensity of >50% of the initial values, strongly suggesting the presence of myocardial inflammation (2). Evaluation of LGE images revealed the presence of LGE (15% of the total myocardial mass) in the lateral wall of the LV (Figure 1). The LVEF was decreased (LVEF = 45%, end-diastolic volume = 97 mL, end-systolic volume = 55 mL) and pericardial effusion was not identified. The patient was treated with angiotensin-converting enzyme inhibitors and β-blockers. Six months later, re-evaluation using CMR revealed normal T2 and EGE, disappearance of LGE and normalization of LVEF.

Figure 1).

Four-chamber image with evidence of positive LGE (arrow) in the lateral wall, due to myocardial inflammation in the course of polymyalgia rheumatica

DISCUSSION

To the best of our knowledge, we report the first case of myocardial inflammation detected by CMR in the setting of PMR, which led to LV deterioration and required further therapeutic intervention in addition to steroids. Myocardial involvement was symptomatic and resistant, despite the complete resolution of musculoskeletal symptoms and abatement of inflammatory markers. While echocardiography revealed LV impairment, it was unable to identify the underlying abnormality, which was further explored using CMR. The latter documented myocardial inflammation using the T2 ratio, increase of myocardial signal of >50% and LGE. Interestingly, the muscular signal remained high, even when clinical evidence of muscular inflammation had disappeared. Altogether, these findings suggest that the heart can be involved in PMR and the muscular signal of inflammatory muscles may remain high even after the disappearance of muscular symptoms.

PMR is an inflammatory disease of the elderly characterized by aching and stiffness in the proximal regions of the extremities and torso and elevated inflammatory markers. Approximately 10% to 15% of patients who appear to have only PMR exhibit temporal artery biopsies findings compatible with giant cell arteritis. In the absence of the latter, PMR has a benign course and responds to low doses of steroids (3).

Cardiovascular involvement during PMR is quite unexplored, with limited data available to date. In an earlier report, approximately 30% of PMR patients had at least one cardiovascular event (myocardial infarction or de novo heart failure) with a cumulative incidence reaching 50% by 10 years (3). Aortic stiffness has been also found to be increased in PMR and institution of steroids appears to be beneficial (4).

Although cardiac inflammation by CMR in inflammatory myopathies has been previously demonstrated (5,6), this is the first time that myocardial inflammation was identified in the setting of PMR. Therefore, we conclude that, in addition to inflammatory myopathies, potential cardiac involvement should be carefully evaluated in PMR, in the presence of relevant symptoms. The high sensitivity of CMR in detecting myocardial inflammation supports its key role in the diagnostic evaluation of PMR.