CAHMO#YOPA7HY Effect of Verapamil on Absolute Myocardial Blood Flow in -wpertrophic Cardiomyopathy Roberto Gistri, MD, Franc0 Cecchi, MD, Lubna Choudhury, MRCPI, Alessio Montereggi, MD, Oreste Sorace, Piero A. Salvadori, PhD, and Paolo G. Camici, MD An@na,despba~@ogfaphicallynomraicoronary arteries, is a common symptom in patients with hypertrophiccardiomyopathy (HC). Verapamil has been shown to ameliorate silent myocardiai per- fusion defects documented by thallium201 in patients with HC. The aim of thii study was to investigate the effects of verapamii on absoiute regumai myocardiai blood flow and flow reserve, measured by posibon emission tomo@aphy (PE7) in patients with HC. Echocardiwphy, exercise stress testin& and measurements of myocardial blood flow at rest and after adminis- tration of inttavenous dipyridamole (0.58 mg/kg) were undertaken in 20 patients with HC at base line study and 8 f 2 weeks after doubieMnd randomization to either dowrelease verapamii 240 mg or piacebo once daily. During treatment, resting myocardial blood flow in the interventricular septum was 0.81 f 0.23 versus 0.98 f 0.42 mi/min/g in the place- bo and verapamii group, respectively (p q NS between groups and when compared with respective baseline study); resting myocardiai blood flow in the left ventricular free wall was 0.87 + 0.17 versus 0.74 + 0.45 mi/min/g, respectively (p = NS). After dipyrklamole infu- sion, myocardiai biood flow in the ZnterVentticu- lar septum was 1.42 f 0.52 versus 1.92 * 1.23 ml/min/g (p = NS between groups and when compared with reqective baseline study); myo- catdial blood flow in the left ventricular free wall was 1.25 + 0.41 versus 1.88 * 1.37 ml/min/& respectively (p = NS). Coronary fiow reserve before and after treatment was 1.95 + 0.82 ver- sus 1.89 f 0.73 (p = NS) in the interventricular septum and 2.15 f 0.74 versus 1.98 + 0.89 in the left ventricular free wail (p = NS) in the placebo and verapamii groups, respectively. Evi- dence of subendocardiai underperfusion was found in 3 of 7 patients with interventricular septal thickness ~25 mm while not receiving treatment. Two of these 3 patients received vet- From the Consiglio Nazionale delle Ricerche (CNR) Institute of Clini- cal Physiology and Istituto di Patologia Medica, University of Pisa and the Cardiologia S. Luca Unita Sanitaria Locale lOD/lOE, Florence, Italy. This study was supported in part by a grant from Knoll Italia Spa, Milano, Italy. Manuscript received December 6, 1993; revised manuscript received and accepted February 22, 1994. Address for reprints: Paolo G. Camici, MD, MRC Cyclotron Unit, Hammersmith Hospital, Du Cane Road, London W12 OHS, United Kingdom. apamii, and in 1 normalization of transmural myocardial blood flow was observed. In conclu- sion, short-term treatment with 240 mg of slow- release verapamil once daiJy does not affect absolute myocardial Mood flow and coronary flow reserve in patients with HC. Subendocardial underperfusion may occur in patients with this condition and verapamii may have a positive effect on transmurai biood flow distribution. (Am J Cardioi l-74383-388) C hest pain suggestive of reversible myocardial ischemia is a common symptom in patients with hypertrophic cardiomyopathy (HC).’ Reversible perfusion defects on thallium-201 scanning2 as well as net lactaterelease in the coronary sinus during atria1 pac- ing3 have been demonstrated in patients with HC. Coro- nary flow reserveis blunted in these patients despite an- giographically normal coronary arteries.4 In addition, evidence of transmural maldistribution of blood flow, with a reducedsubendocardial to subepicardialflow ratio, after administration of intravenous dipyridamole, has been demonstratedin patients with HC using positron emissiontomography (PET).5Verapamil hasbeenshown to ameliorate angina6 and silent myocardial perfusion defects documented by thallium-201 scintigraphy in these patients.7 To investigate the effects of verapamil on absolute myocardial blood flow and flow reserve, measuredby means of nitrogen-13 ammonia and PET, we performed a double-blind placebo-controlled study in 20 patients with HC. METHODS Study group: We studied 20 normotensive patients (15 men and 5 women) with HC, aged 40 + 10 years (range 23 to 54). All patients were mildly symptomatic (8 and 12 patients were in New York Heart Association functional class II and I, respectively) and all were in sinus rhythm. Mean septal thickness was 24 f 6 mm (range 17to 39). A family history of HC or sudden death, or both, was present in 13 patients. Study protocol: After current drug therapy had been withdrawn for at least 1 week, all patients underwent a complete echocardiographic study, exercise stress test, and measurements of regional myocardial blood flow and flow reserve by PET before randomization to receive either verapamil (a single daily dose of 240 mg, slow release) or verapamil-placebo, with 10 patients in each group. No patient was taking amiodarone. These inves- tigations were repeated in 18 patients after 8.0 & 2.4 VERAPAMILAND MYOCARDIAL BLOOD FLOW IN HC 363