R-wave amplitude response to myocardial ischemia in hypertrophic cardiomyopathy.

Abstract: Background and Purpose: R-wave amplitude change during exercise has been reported to enhance diagnostic value for myocardial ischemia in coronary heart disease. Methods: We summed up R-wave amplitude in all the 12 leads during exercise testing and correlated the results with regional myocardial ischemia or diffuse subendocardial ischemia as detected by scintigraphy in 49 patients with hypertrophic cardiomyopathy (HCM) and 16 controls. Results: The sum of R-wave amplitude decreased during exercise in patients with HCM (mean, 12.4 mV to 11.7 mV, P < .01) as well as in controls (8.0 mV to 7.7 mV, P < .05). Percent changes in the sum of R-wave amplitude did not differ between 4 subgroups of patients with HCM: one having both regional and subendocardial ischemia, one only the former, one only the latter, and one neither of them (mean, 6.5%, 7.7%, 4.6%, and 5.1%; P = .79). Conclusions: R-wave amplitude response to exercise failed to demonstrate myocardial ischemia in our patients with HCM. [Copyright &y& Elsevier]