Transmural myocardial blood flow distribution in hypertrophic cardiomyopathy and effect of treatment

L. Choudhury, P. Elliott, O. Rimoldi, M. Ryan, A. A. Lammertsma, H. Boyd, W. J. McKenna, P. G. Camici

Research output: Contribution to journalArticlepeer-review

Abstract

Verapamil alleviates symptoms in patients with hypertrophic cardiomyopathy (HCM), but the underlying mechanism of improvement remains speculative. Baseline and dipyridamole myocardial blood flow (MBF) were measured in 15 HCM patients (14 men, 42 ± 10 years), before and after 4 weeks of verapamil SR 480 mg daily, using 15O labelled water and positron emission tomography (PET). Subendocardial (endo) and subepicardial (epi) MBF was measured in the septum (thickness 25.4 ± 5.8 mm). Pre-treatment baseline whole heart MBF was 1.02 ± 0.28 ml/min/g and 1.01 ± 0.30 ml/min/g on treatment (p = ns). Dipyridamole MBF was 1.39 ± 0.31 ml/min/g off treatment and 1.23 ± 0.34 ml/min/g on treatment (p = ns). Coronary flow reserve (dipyridamole/resting MBF) was 1.45 ± 0.52 and 1.30 ± 0.51, respectively (p = ns). At baseline, the septal endo/epi MBF ratio was uniform off and on treatment (1.13 ± 0.18 vs 1.18 ± 0.21, p = ns). Before treatment, the endo/epi ratio following dipyridamole decreased to 0.93 ± 0.24 (p <0.01 vs baseline) and 5/15 (33%) patients had a ratio <0.8 which would suggest subendocardial underperfusion. During treatment, the endo/epi ratio following dipyridamole was no more different from baseline (1.06 ± 0.24, p = ns vs baseline) and 2/14 (14 %) patients had an endo/epi <0.8. PET can be successfully used to determine transmural MBF in vivo in patients with hypertrophied ventricles. Despite symptomatic improvement, high dose verapamil therapy does not increase total MBF in patients with HCM but may improve septal transmural MBF distribution during dipyridamole in some patients.

Original languageEnglish
Pages (from-to)49-59
Number of pages11
JournalBasic Research in Cardiology
Volume94
Issue number1
DOIs
Publication statusPublished - Feb 1999

Keywords

  • Calcium channel blockers
  • Hypertrophic cardiomyopathy
  • Positron emission tomography
  • Transmural blood flow

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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