PET abnormalities in patients with nonischemic cardiomyopathy

https://doi.org/10.1016/j.cardfail.2003.09.007Get rights and content

Abstract

Background

The abnormalities in dilated cardiomyopathy (DCM) are generally considered diffuse and to affect the left ventricle in a global manner. However, regional wall motion abnormalities and metabolic defects may also occur to varying, but unclear degrees. QRS width and metabolic defects on positron emission tomography (PET) correlate with survival. We sought to ascertain the prevalence of regional defects in DCM by multiple imaging modalities and to establish the relationship between QRS width and these defects.

Methods

In consecutive patients with advanced nonischemic DCM, undergoing cardiac transplant evaluation, we reviewed multiple imaging modalities (PET, 2-dimensional echocardiography, and radionuclide ventriculography) to quantify the incidence of regional metabolic and wall motion abnormalities and correlate them with clinical and electrocardiographic parameters.

Results

Of 44 patients studied, PET imaging revealed scar in 91% of patients, with a mean of 25 ± 18% of the left ventricle involved, predominantly in the distribution of the left anterior descending artery. Regional wall motion abnormalities occurred in 51% of patients who underwent echocardiography and 59% of patients who underwent nuclear scintigraphy (with only 70% concordance). QRS duration on the surface electrocardiogram correlated positively with the degree of scarring (r = .52, P = .0007).

Conclusions

The presence of scar (matched perfusion and metabolic defects) on PET scanning in patients with advanced DCM is not always indicative of coronary disease. Thus coronary angiography is usually required to define the etiology of systolic dysfunction. The extent of scar correlates with QRS duration. This may have implications for the application of cardiac resynchronization therapy.

Section snippets

Study Group

This was a retrospective study, and data were extracted from a database that was approved by the Institutional Review Board of the Cleveland Clinic Foundation. The requirement for obtaining informed consent was waived. Forty-four patients with chronic New York Heart Association class III–IV symptoms (duration >3 months), referred for heart failure evaluation were being considered for cardiac surgical procedures; hence we sought to determine the extent of viable myocardium, defined as myocardium

Results

The clinical characteristics of these patients are described in Table 1. Forty-four patients, mean age 56.8 ± 13 (range 20–75) years, 65% male, were studied. Forty-one (93%) had idiopathic DCM, 15/44 (34%) had atrial fibrillation, and 7/44 (16%) had a history of thromboembolism (4 left ventricular thrombus, 2 transient ischemic attack, and 1 pulmonary embolus).

PET imaging revealed matched Rubidium and FDG defects in 40 of 44 (91%), suggesting the presence of myocardial scar (nonviability). Mean

Discussion

Coronary arteriography is often deferred in favor of less-invasive tests, including echocardiography, nuclear studies, and PET imaging. PET imaging has the advantage that it can evaluate regional metabolic activity in addition to regional perfusion. Pharmacologic stressors can be given to evaluate for ischemia.

The data shown here indicate that regional wall motion and metabolic abnormalities are commonly seen on echocardiography, radionuclide ventriculography, and PET. Those with the longest

Conclusions

Scar seen with PET in patients with DCM is misleading and not indicative of coronary artery disease. Therefore, coronary arteriography is usually required to rule out obstructive coronary disease in patients with DCM because of the limitations of noninvasive imaging modalities.

QRS duration correlates with perfusion and metabolic defects (scar) by PET and may reflect poor prognosis. Effective treatment may reduce these abnormalities. The broad QRS complex seen in DCM may be to a greater or

Acknowledgments

The authors wish to acknowledge the secretarial assistance of Ms. Susan Federico in the preparation of this manuscript.

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