Nuclear Cardiology (08/10): Non-Ischemic Cardiomyopathy
52 yrs old male with past medical history of Afib and HTN (non compliant with β
blocker for rate control) presented to the Emergency Room with a 3 day history
of chest pain. He was admitted for cardiovascular evaluation, including nuclear
stress testing, echocardiography, and cardiac catheterization.
Myocardial perfusion imaging was performed with Dipyridamole stress test
using one day Tc-99m-Tetrofosmin rest-stress protocol. There were no
symptoms or ECG changes to suggest dipyridamole induced myocardial
ischemia. The images do not show any reversible perfusion defects to suggest
presence of dipyridamole induced myocardial ischemia. Left ventricle is dilated
(EDV 176 ccs) and hypertrophied. Gated images show global hypokinesis with
an ejection fraction of 34%. These findings suggest non ischemic
cardiomyopathy. Echocardiography showed left ventricular hypertrophy and
dilatation with a globally reduced ejection fraction of 30-40%.
Subsequent coronary angiography confirmed no significant occlusive disease
in coronary arteries. Pt was discharged with continued medical management
and follow up with his cardiologist for Afib and newly diagnosed non ischemic
cardiomyopathy. ACE inhibitor and diuretic were added to his medical regime
for afterload reduction and fluid control.
Although there are many potential causes of non ischemic CMP (1), a
possibility may be related to his Afib history and being off his rate control meds
for some unknown length of time. One known cause of CMP is tachycardia
induced CMP (2), resulting from Afib with poor HR control; the resulting
tachycardia puts a large workload on the heart with a resulting deterioration in
LV function over time. Although the pt was not tachycardic on evaluation in the
ER, he had been off his rate control meds for some unknown time, and could
quite possibly be tachycardic for frequent unknown lengths of time, that could
eventually have contribute to deterioration of LV function over time.
1) Taylor, G., Primary Care Cardiology, 2nd edition, Blackwell pub, 2005
2) Khasnis et al, PACE July 2005; 28 (7): 710-21
This case was compiled by Dr. David He and Joseph Vollink PA, MEDVAMC