The aim of this study was to relate the contractile reserve in infarction segments to the dysfunction at rest and to the residual coronary stenosis.
The study group consisted of 95 patients with a first myocardial infarction. Contrast left ventricular at baseline and after dobutamine infusion at 7.5 Êg/kg/min and coronary angiograms were performed. The centerline method was used to quantify the extent of dysfunction (percentage of chords with dysfunction in the territory of the infarction artery) and its maximum severity (maximum units of standard deviation [SD] below the normal wall motion reference). Reduction of dysfunction extent with dobutamine was measured.
On increasing baseline dysfunction severity, both the magnitude of the response to dobutamine (. 2 SD [n = 12] = 33 ±} 19%, > 2 SD ≤ 3 SD [n = 20] = 20 ±} 16%, > 3 SD ≤ 4 SD [n = 35] = 16 ±} 19%, > 4 SD ±} 5 SD [n = 15] = 9 ±} 13%, > 5 SD [n = 13] = 3 ±} 4%, p = 0,0001), and the number of patients with a significant (. 15%) positive response (. 2 SD = 12 [100%], > 2 SD ≤ 3 SD = 11 [55%], > 3 SD ≤ 4 SD = 17 [49%], > 4 SD ≤ 5 SD = 3 [20%]; > 5 SD = 0%, p < 0,0001) decreased. There were no differences in dobutamine improvement among the subgroups with (n = 84) or without (n = 11) significant stenosis in the infarction artery (18 ±} 15 vs 16 ±} 18%), or between the subgroups with a patent (n = 76, 18 ±} 19%) or occluded (n = 19, 11 ±} 11%) artery.
Dobutamine response is related to dysfunction severity in the infarction area: when the severity is ≤ 2 (high positive response prevalence) or > 5 (high negative response prevalence), dobutamine testing does not seem indicate. The existence of residual coronary stenosis does not attenuate contractile reserve at low dobutamine doses.
[Show abstract][Hide abstract] ABSTRACT: The objective of this study was to use low-dose dobutamine (LDD) gated single-photon emission computed tomography (SPECT) to evaluate segmental thickening of the left ventricle (LV) and its relationship with changes in ejection fraction (EF) and ventricular volumes in patients with ischemic cardiomyopathy.
This prospective multicenter study involved 89 patients with ischemic cardiomyopathy (i.e., EF < or =40%) who underwent LDD gated-SPECT at rest. The LV was divided into 17 segments and systolic thickening was assessed in a total of 1513 segments during LDD infusion. RESULTS; A significant increase in LVEF (33.2% vs. 30.8%; P< .001) was observed during LDD infusion and occurred at the expense of a reduction in end-systolic volume (130.5 mL vs. 136.4 mL; P=.005). The increase in EF was > or =5% in 33.7% of patients, while the EF decreased by > or =5% in 5.6% of patients. With LDD infusion, both an improvement in > or =3 segments with severely decreased baseline thickening (odds ratio [OR] = 18.3; 95% confidence interval [CI], 5.3-63) and an improvement in > or =10 segments with mild-to-moderate alterations in baseline thickening (OR = 4.53; 95% CI, 1.26-16.16) were associated with a > or =5% increase in LVEF.
During the assessment of global left ventricular contractile reserve by LDD gated-SPECT, attention should be paid not only to the behavior of segments with severely decreased baseline thickening, which are generally regarded as indicating viability, but also to segments with mild-to-moderate alterations and to those in which thickening decreases.
Revista Espa de Cardiologia 11/2008; 61(10):1061-9. DOI:10.1016/S1885-5857(09)60009-8 · 3.79 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To investigate negative contractile responses in the left ventricle during low-dose dobutamine (LDD) gated single-photon emission computed tomography (SPECT) in patients with ischemic cardiomyopathy.
Sixty-eight consecutive patients (mean age, 60 + or - 11 years; 7 male) with ischemic cardiomyopathy (i.e., left ventricular ejection fraction [LVEF] < or = 40%) were evaluated using gated-SPECT at rest and during LDD infusion. Associations between a negative contractile reserve (i.e., a > or = 1-grade improvement in wall thickening score with LDD infusion) and scintigraphic viability criteria and coronary angiography findings were analyzed.
Some 42.6% (29/68) of patients had a negative contractile reserve in one or more segments. In 14.7% (n=10), the LVEF decreased by > or = 4% with LDD. These patients had more segments with a negative contractile reserve (2.8 + or - 2.5 vs. 0.87 + or - 0.40; P=.042), and the cut-off value on receiver operating characteristic curve analysis was > or =2 segments with a negative contractile reserve (sensitivity 70%, specificity 74%, positive likelihood ratio 2.71, negative likelihood ratio 0.40). Some 94% (74/79) of segments with a negative contractile reserve were in viable myocardium (i.e. normal or viable on scintigraphy). Twelve of 17 segments with akinesia or severe hypokinesia and a negative contractile reserve satisfied scintigraphic viability criteria, with the majority (10/12) lying in territories supplied by a patent coronary artery.
A negative contractile reserve was not uncommon in patients with ischemic cardiomyopathy and was associated with a general decrease in left ventricular systolic function. It was observed mainly in myocardial segments that appeared viable on scintigraphy and were supplied by a patent coronary artery.
Revista Espa de Cardiologia 02/2010; 63(2):181-9. DOI:10.1016/S1885-5857(10)70036-0 · 3.79 Impact Factor
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