Key result
Normal ischemia detection criteria reduce specificity by ~15% in hearts with increased LV mass.
Why the study?
Detailed quantitative analysis of the effect of left ventricle hypertrophy on myocardial ischemia manifestation in ECG is still missing.
May increase false positives when applying normal-heart ischemia criteria to LVH; leaves open validation of mass-adjusted thresholds in humans.
BACKGROUND: Detailed quantitative analysis of the effect of left ventricle (LV) hypertrophy on myocardial ischemia manifestation in ECG is still missing. The associations between both phenomena can be studied in animal models. In this study, rabbit isolated hearts with spontaneously increased LV mass were used to evaluate the effect of such LV alteration on ischemia detection criteria and performance. METHODS: Electrophysiological effects of increased LV mass were evaluated on sixteen New Zealand rabbit isolated hearts under non-ischemic and ischemic conditions by analysis of various electrogram (EG) parameters. To reveal hearts with increased LV mass, LV weight/heart weight ratio was proposed. Standard paired and unpaired statistical tests and receiver operating characteristics analysis were used to compare data derived from different groups of animals, monitor EG parameters during global ischemia and evaluate their ability to discriminate between unchanged and increased LV as well as non-ischemic and ischemic state. RESULTS: min) of ischemia. Besides ischemia, these parameters reflect increased LV mass as well (with sensitivity reaching approx. 80%). However, the sensitivity of the parameters to both phenomena may lead to misinterpretations, when inappropriate criteria for ischemia detection are selected. Particularly, use of cut-off-based criteria defined from control group for ischemia detection in hearts with increased LV mass may result in dramatic reduction (approx. 15%) of detection specificity due to increased number of false positives. Nevertheless, criteria adjusted to particular experimental group allow achieving ischemia detection sensitivity of 89-100% and specificity of 94-100%, respectively. CONCLUSIONS: It was shown that response of the heart to myocardial ischemia can be successfully evaluated only when taking into account heart-related factors (such as LV mass) and other methodological aspects (such as recording electrodes position, selected EG parameters, cut-off criteria, etc.). Results of this study might be helpful for developing new clinical diagnostic strategies in order to improve myocardial ischemia detection in patients with LV hypertrophy.
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Ronzhina et al. (2017) studied Myocardial ischemia with left ventricular mass alteration (n=16). Increased left ventricular (LV) mass fraction vs. Normal (low) left ventricular mass fraction was evaluated on Specificity of ischemia detection using AUC QRS cut-offs. In an isolated rabbit heart model, using ischemia detection criteria defined from normal hearts on those with increased left ventricular mass reduced detection specificity by approximately 15% due to an increased number of false positives.
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