Objectives: Knowledge of cardiac involvement in idiopathic inflammatory myopathies (IIM) is limited, especially in the early stage of disease. The objective of the present study was to perform a controlled evaluation of cardiac abnormalities in newly diagnosed, untreated patients with idiopathic inflammatory myopathies (IIM) by means of non-invasive techniques.
Methods: Fourteen patients with IIM (8 polymyositis, 4 dermatomyositis, 2 cancer-associated dermatomyositis) and 14 gender- and age- matched healthy control subjects were investigated. Participant assessments included a cardiac questionnaire, cardiac troponin-I (TnI), electrocardiogram (standard 12-lead and 48-h Holter monitoring), echocardiography with tissue Doppler measures, cardiac magnetic resonance (CMR) imaging with T2 mapping and semi-quantitative (99m)technetium pyrophosphate ((99m)Tc-PYP) scintigraphy.
Results: Dyspnoea was present in 8 (57%) of the patients compared to none of the controls (p<0.01). Median levels of TnI in patients and controls were 20 ng/L and 6 ng/L, respectively (p=0.06). QTc intervals were prolonged in the patient group (p=0.01). Two patients had systolic dysfunction, and one diastolic dysfunction. The myocardial (99m)Tc-PYP uptake and CMR results differed between patients and controls, albeit not with statistical significance. Overall, cardiac abnormalities were demonstrated in 9 (64%) of the patients versus 2 (14%) of the controls (p=0.02).
Conclusions: Cardiac abnormalities assessed by TnI, ECG or imaging modalities were significantly more common in newly diagnosed, treatment naïve patients with IIM compared to healthy control subjects. These abnormalities, although subclinical, may indicate that myocardial involvement is common in patients and calls for larger controlled studies and further investigations of the prognostic implications of this finding.