Background The myocardium involvement in patients with inflammatory myopathy constitutes one of the main causes of mortality. The early identification of these patients is crucial to improve the prognosis of the disease. Strain rate analysis is a new method that allows the detection of premature dysfunction of myocardial muscle.
Objectives Assess the heart involvement in patients with inflammatory myopathy through Doppler echocardiography with strain rate analysis using speckle tracking.
Methods Observational analysis of a sample of patients with polymyositis (PM) or dermatomyositis (DM) selected from the Rheumatology outpatient clinic of a Portuguese University Hospital. Demographic and clinical data were collected in each patient (past medical and therapeutic history). Disease activity was assessed through evaluation of muscle strength using Manual Muscle Testing Score of 8 muscle groups (MM8), patient and physician visual analogic scale (VAS), and with laboratorial data, namely determination of muscle enzymes (CK, aldolase, myoglobin and troponin) and BNP. Patients were submitted to a standard transthoracic Doppler echocardiogram, and the images were later processed with strain rate analysis.
Results Between June and December/2013, 9 patients fulfilled the inclusion criteria, and an echocardiogram was performed in eight of them. The selected sample had a median age of 60 years (50-86), 88.9% (n=8) of which were women. 55.6% (n=5) had DM and 44.4% (n=4) patients have PM. The first manifestation of the disease was muscle weakness/myalgia in all but 1 patient, but all patients had muscular involvement at any point. The median duration of the disease was 2 years. Seven patients had pulmonary involvement secondary to the disease. Two patients had overlap with other rheumatic disease (systemic sclerosis), and 1 patient had anti-synthetase syndrome with anti-Jo1 positivity.
All patients had been treated with glucocorticoids; 7 patients had undergone treatment with methotrexate or azathioprine. Five patients had been treated with intravenous immunoglobulin, and 4 patients had been treated with cyclophosphamide, aimed to the lung involvement.
The median MM8 was 122, median patient VAS 47 mm, and median physician VAS 30 mm. Half of the patients had elevation of CK and aldolase, and only 22% had elevation of myoglobin.
On echocardiogram, only one patient had a left ventricular ejection fraction below normal (at 48%). Fifty percent (n=4) had reduced global longitudinal strain (median -9.67; normal ≤ -16). One of these 4 patients also had severe pulmonary hypertension, with a pulmonary artery systolic pressure of at least 70 mmHg. Other echocardiographic parameters were within the normal range. BNP was elevated in 2 of them, but other cardiac biomarkers, namely troponin, were within the normal range. BNP was also elevated in one other patient with normal echocardiogram.
Conclusions Despite the small number of patients enrolled in the study, half of them had evidence of subclinical myocardial dysfunction assessed by echocardiographic strain imaging. We suggest that there can be a role for the routine determination of strain during echocardiography among the patients with inflammatory myopathy, as it can detect subtle dysfunction, with possible therapeutic implications.
Disclosure of Interest None declared