Recently, increased interest has been devoted to left ventricular diastolic dysfunction. Some authors suggest that this type of dysfunction occurs only in SSc patients with systemic and/or pulmonary hypertension, ventricular hypertrophy and pericardial disease. Other authors believe that diastolic abnormalities in SSc reflect primary involvement of the myocardium that may precede systolic dysfunction or may relate to subclinical myocardial involvement occurring even as early as the onset of Raynaud’s phenomenon.6 This frequent symptomless coronary vasospasm may contribute to myocardial dysfunction.
Diagnosis
1) Echocardiography: In SSc, baseline and serial echocardiography with Doppler should be performed to achieve important information about left and right ventricular morphology and function, valvular function, and/or pericardial effusion. Using improved echochardiographic techniques, like tissue Doppler imaging, regional systolic diastolic abnormalities and direct measures of myocardial velocities can be detected, offering the opportunity of more accurate follow up and earlier treatment. One recent study suggests that the presence of diastolic dysfunction in SSc patients reflects an early asymptomatic myocardial fibrosis, identifying those patients with higher risk for cardiac impairment. Left ventricular diastolic dysfunction is expressed by an inverted E/A ratio that represents early and late ventricular filling during atrial contraction.7 Recently, the use of TDI techniques may improve the detection of heart involvement showing the depression of left and right ventricular systolic and left ventricular diastolic function.8
2) Magnetic resonance imaging (MRI): MRI is superior to other techniques for the assessment of ventricular size, function, and mass because it is non-invasive and has high spatial resolution, high reproducibility, and low inter-observer and intra-observer variability. High-resolution perfusion MRI techniques can identify small subendocardial defects and may allow a non-invasive determination of coronary reserve and the evaluation of fibrotic myocardium compared with viable tissue. Two recent studies indicate that MRI may detect subclinical right heart involvement and can identify myocardial fibrosis in a significant percentage of SSc patients.9 MRI is a valuable tool but the high cost still limits its use.10
3) Myocardial biopsy (MB): In clinical practice, the use of MB is limited by invasiveness of the procedure and high rate of sampling errors as shown by its relatively low diagnostic yield compared with that of autopsy. MB is indicated when there is clinical concern for the presence of other cardiac pathologies that might overlap with SSc. An immunohistological study of MB revealed myocarditis and an increased amount of fibroblast, suggesting that more frequent use of MB might lead to more differentiated therapies. In fact, in this study, an increased amount of AS02-positive fibroblast was found in the myocardium of both SSc patients in comparison with the controls, suggesting that fibroblasts are over-represented in the SSc myocardial tissue of patients in comparison with other myocardial diseases. However, the utility of MB is significantly limited by risks and the possibility of sampling error due to patchy heart involvement.11
Treatment
Early treatment with vasodilators such as calcium channel blockers and angiotensin converting enzyme inhibitors has been shown to be beneficial on myocardial perfusion and function and may help to limit the progression of major life-threatening complication of the disease. Up to now, no antifibrotic therapy has been shown to preview or control myocardial fibrosis.
Vascular Piece of the Puzzle
In SSc, despite of the prominence of vascular abnormalities and documented ischemia, the incidence of coronary artery disease does not seem different from that of the general population.12 Characteristic SSc vascular lesions result in major impairment of the microcirculation. Histological examinations reveal concentric intimal hypertrophy associated with fibrinoid necrosis of intramural coronary arteries. In addition, vasospasm of the small coronary arterioles mimicking a myocardial Raynaud’s phenomenon induce contraction band necrosis that are ischemic tiny fibrotic areas of the myocardium. Two recent studies using enhanced transthoracic Doppler before and after adenosine infusion have confirmed the reduction of coronary reserve in SSc patients without clinical evidence of cardiac involvement. The functional and structural abnormalities of the small coronary circulation are now considered the first pathologic step of the disease that leads to late fibrotic patchy ischemic lesions.
Diagnosis
1) Single photon emission computed tomography (SPECT): The acquisition of perfusion scintigraphy using gated SPECT is an important development of nuclear medicine. Gated SPECT allows the automated calculation of left ventricular ejection fraction (LVEF) and the assessment of regional function using perfusion images. A good correlation exists between resting gated SPECT and other imaging techniques for the calculation of LVEF and the assessment of regional wall motion and thickening. The simultaneous assessment of perfusion and function is helpful for the diagnostic and prognostic assessment of patients with chronic coronary artery disease like SSc patients.
