Decreased Coronary Vasodilatory Capacity in Hypertrophic Cardiomyopathy Determined by Split-Dose Thallium-Dipyridamole Myocardial Scintigraphy Yoshinori Koga, MD, Ryutaro Yamaguchi, MD, Masahiko Ogata, MD, Kazuo Kihara, MD, and Hironori Toshima, MD Split-dose thalliim-dipyridamob myocardial sclntigraphy was performed in patients with nonobstructlve hypertrophk cardiomyopathy (HC) who had angiographically notma1 coronary arterbs. The dipyrihmob-induced increases in thallium-201 uptake, cakubted to evahrate coronary vasodibtory capacity, were signi6cantly lower in 36patbntswithHCthanln13controlsubje&s (177 f S6 vs 281 f 46%) and the reductions were observed in both the septal and lateral segments. The reductlolu of the septal segment in HC patients were slgnifkantly greater than those in 10 hypertenslve patients with comparabb degrees of septal h-y. Of patbnts with HC, 16 had Increases in thallkan uptake well below the normal range. compared wlth those having normal htcreases, these patbnts had significantly lower exercise duration (11 VI 15 minutes), with 33% having ST depressbn develop at a workload 166 watts. These data indicate that approximately one-half of paimportati~ &physiocapacity that could be logic abnormality of HC resulting In the development of myocardlal ischemia and the impairment of cardll peffomwnce during exercbe. (AmJCardid 1990;65:1134-1139)

hestpain and ischemicST depressionare manifestations frequently presentedby patients with hypertrophic cardiomyopathy (HC), despite the appearanceof normal coronary angiograms.Our previous studies,’ as well as others,2-4have shown that pacing stress could induce lactate production in these patients. Myocardial thallium-201 scintigraphic studies5 have shown that patients with HC developedreversible as well as fixed perfusion defects. These observations have clearly indicated that exercise or atria1 pacing could induce myocardial ischemia in this condition. Previous studies in coronary hemodynamics2-4have shown that in patients with HC, the increasein coronary flow during atria1 pacing is limited, these studies have proposeda reduced coronary vasodilatory reserveas a possible mechanism for myocardial ischemia in this condition. However, since atria1 pacing or exercise cannot induce maximal dilatation of coronary vessels,the coronary vasodilatory reservehas not beenprecisely evaluated in these previous studies. In addition, there remains the possibility, as suggestedby Cannon et a1,4that an elevation of left ventricular end-diastolic pressure, which results from pacing-inducedmyocardial ischemia, could in turn cause a decreasein coronary blood flow. This investigation was accordingly designed to study maximal coronary vasodilatory capacity in patients with HC using split-dose thallium-dipyridamole myocardial scintigraphy.6*7

C

METHODS Patient sektion:

Between February 1984 and July 1985,a total of 45 patients fulfilled the diagnostic criteria of HC at our hospital basedon 2dimensional echocardiography, left ventriculography and coronary angiography. For this study, we excluded 6 patients with an intraventricular pressuregradient 220 mm Hg during basal conditions, in consideration of dipyridamole further increasing the outflow obstruction. We also excluded 3 patients with apical hypertrophy presenting with a spadeshaped left ventricle, 2 patients with associated organic coronary artery stenosis and 4 patients who could not discontinue cardiac medications. The final From the Third Department of Medicine, Kurume University Schoolof study group consistedof 18 men and 12 women, rangMedicine, Kurume, Japan. This study was supported in part by a ing in age from 15 to 69 years (mean 39). Seven researchgrant for intractable diseasesfrom the Ministry of Health and healthy men and 6 healthy women ranging in age from Welfare of Japan. Manuscript receivedJuly 5,1989; revisedmanuscript 21 to 57 years (mean 41) volunteered to serve as the receivedand acceptedJanuary 3,199O. Addressfor reprints: Yoshinori Koga, MD, The Third Department control group. For comparison, we examined 10 paof Medicine, Kurume University Schoolof Medicine, 67 Asahi-machi, tients, 8 men and 2 women, ranging in age from 42 to Kurume 830, Japan. 62 years (mean 52) who had systemic hypertension and i 134

THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 65

symmetric left ventricular hypertrophy with a posterior wall thickness I1 5 mm. Neither control subjects nor patients with hypertension developedST depressionon the bicycle ergometer stress test, nor did they have reversible or fixed defect on the thallium-201 myocardial scintigram. Coronary angiography was performed in 8 of 10 hypertensive patients who had complained of chest pain; no abnormality was revealed in these 8 patients. Informed consent was obtained from all of the study subjects. Split-dose

thallium-201

myocardial

TABLE

alnhier oblique (30”) proi8cuon over 10 mim8tes.

41 f 16

Age Ws) Sex (M/F) HR (beats/min) Mean blood pressure (mm Hg) Septal thickness (mm) Posterior wall thickness (mm) End-diastolic diameter (mm) Fractional shortening (%)

scintigraphy:

7/6 62&6 86 f 8 IOf1 9fl 47f5 38i6

Hypertension

HC

52f7*

39f 15+ 18/12 62f6 87 f 145 19zt6’ 12 f 3*5 43f5’ 37510

g/2 63f12 lllfl4~ 18+3* 17 f 1* 45f6 39f7

Values are mean f standard deviation. * p ~0.05. t p

Decreased coronary vasodilatory capacity in hypertrophic cardiomyopathy determined by split-dose thallium-dipyridamole myocardial scintigraphy.

Split-dose thallium-dipyridamole myocardial scintigraphy was performed in patients with nonobstructive hypertrophic cardiomyopathy (HC) who had angiog...
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