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Mechanism of decreased sensitivity of dobutamine associated left ventricular wall motion analyses for appreciating inducible ischemia in older adults.

ABSTRACT: Dobutamine associated left ventricular (LV) wall motion analyses exhibit reduced sensitivity for detecting inducible ischemia in individuals with increased LV wall thickness. This study was performed to better understand the mechanism of this reduced sensitivity in the elderly who often manifest increased LV wall thickness and risk factors for coronary artery disease.During dobutamine cardiovascular magnetic resonance (DCMR) stress testing, we assessed rate pressure product (RPP), aortic pulse wave velocity (PWV), LV myocardial oxygen demand (pressure volume area, PVA, mass, volumes, concentricity, and the presence of wall motion abnormalities (WMA) and first pass gadolinium enhanced perfusion defects (PDs) indicative of ischemia in 278 consecutively recruited individuals aged 69?±?8 years with pre-existing or known risk factors for coronary artery disease. Each variable was assessed independently by personnel blinded to participant identifiers and analyses of other DCMR or hemodynamic variables.Participants were 80% white, 90% hypertensive, 43% diabetic and 55% men. With dobutamine, 60% of the participants who exhibited PDs had no inducible WMA. Among these participants, myocardial oxygen demand was lower than that observed in those who had both wall motion and perfusion abnormalities suggestive of ischemia (p?=?0.03). Relative to those with PDs and inducible WMAs, myocardial oxygen demand remained different in these individuals with PDs without an inducible WMA after accounting for LV afterload and contractility (p?=?0.02 and 0.03 respectively), but not after accounting for either LV stress related end diastolic volume index (LV preload) or resting concentricity (p?=?0.31-0.71).During dobutamine stress testing, elderly patients experience increased LV concentricity and declines in LV preload and myocardial oxygen demand, all of which are associated with an absence of inducible LV WMAs indicative of myocardial ischemia. These findings provide insight as to why dobutamine associated wall motion analyses exhibit reduced sensitivity for identifying inducible ischemia in elderly.This study was registered with Clinicaltrials.gov (NCT00542503).

SUBMITTER: Vasu S

PROVIDER: S-EPMC4389511 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature

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Mechanism of decreased sensitivity of dobutamine associated left ventricular wall motion analyses for appreciating inducible ischemia in older adults.

Vasu Sujethra S Little William C WC Morgan Timothy M TM Stacey Richard B RB Ntim William O WO Hamilton Craig C Thohan Vinay V Chiles Caroline C Hundley William Gregory WG

Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance 20150408

<h4>Background</h4>Dobutamine associated left ventricular (LV) wall motion analyses exhibit reduced sensitivity for detecting inducible ischemia in individuals with increased LV wall thickness. This study was performed to better understand the mechanism of this reduced sensitivity in the elderly who often manifest increased LV wall thickness and risk factors for coronary artery disease.<h4>Methods</h4>During dobutamine cardiovascular magnetic resonance (DCMR) stress testing, we assessed rate pre ...[more]

PMID: 25885436

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Project description:OBJECTIVES:The study objectives were to test the hypotheses that ischemia during stress testing has prognostic value and identifies those patients with coronary artery disease (CAD) with left ventricular (LV) dysfunction who derive the greatest benefit from coronary artery bypass grafting (CABG) compared with medical therapy. BACKGROUND:The clinical significance of stress-induced ischemia in patients with CAD and moderately to severely reduced LV ejection fraction (EF) is largely unknown. METHODS:The STICH (Surgical Treatment for IsChemic Heart Failure) trial randomized patients with CAD and EF ?35% to CABG or medical therapy. In the current study, we assessed the outcomes of those STICH patients who underwent a radionuclide (RN) stress test or a dobutamine stress echocardiogram (DSE). A test was considered positive for ischemia by RN testing if the summed difference score (difference in tracer activity between stress and rest) was ?4 or if ?2 of 16 segments were ischemic during DSE. Clinical endpoints were assessed by intention to treat during a median follow-up of 56 months. RESULTS:Of the 399 study patients (51 women, mean EF 26 ± 8%), 197 were randomized to CABG and 202 were randomized to medical therapy. Myocardial ischemia was induced during stress testing in 256 patients (64% of the study population). Patients with and without ischemia were similar in age, multivessel CAD, previous myocardial infarction, LV EF, LV volumes, and treatment allocation (all p = NS). There was no difference between patients with and without ischemia in all-cause mortality (hazard ratio: 1.08; 95% confidence interval: 0.77 to 1.50; p = 0.66), cardiovascular mortality, or all-cause mortality plus cardiovascular hospitalization. There was no interaction between ischemia and treatment for any clinical endpoint. CONCLUSIONS:In CAD with severe LV dysfunction, inducible myocardial ischemia does not identify patients with worse prognosis or those with greater benefit from CABG over optimal medical therapy. (Comparison of Surgical and Medical Treatment for Congestive Heart Failure and Coronary Artery Disease [STICH]; NCT00023595).

Project description:BackgroundThe presence of left ventricular (LV) wall motion abnormalities (WMA) is an independent indicator of adverse cardiovascular events in patients with cardiovascular diseases. We develop and evaluate the ability to detect cardiac wall motion abnormalities (WMA) from dynamic volume renderings (VR) of clinical 4D computed tomography (CT) angiograms using a deep learning (DL) framework.MethodsThree hundred forty-three ECG-gated cardiac 4DCT studies (age: 61 ± 15, 60.1% male) were retrospectively evaluated. Volume-rendering videos of the LV blood pool were generated from 6 different perspectives (i.e., six views corresponding to every 60-degree rotation around the LV long axis); resulting in 2058 unique videos. Ground-truth WMA classification for each video was performed by evaluating the extent of impaired regional shortening visible (measured in the original 4DCT data). DL classification of each video for the presence of WMA was performed by first extracting image features frame-by-frame using a pre-trained Inception network and then evaluating the set of features using a long short-term memory network. Data were split into 60% for 5-fold cross-validation and 40% for testing.ResultsVolume rendering videos represent ~800-fold data compression of the 4DCT volumes. Per-video DL classification performance was high for both cross-validation (accuracy = 93.1%, sensitivity = 90.0% and specificity = 95.1%, κ: 0.86) and testing (90.9, 90.2, and 91.4% respectively, κ: 0.81). Per-study performance was also high (cross-validation: 93.7, 93.5, 93.8%, κ: 0.87; testing: 93.5, 91.9, 94.7%, κ: 0.87). By re-binning per-video results into the 6 regional views of the LV we showed DL was accurate (mean accuracy = 93.1 and 90.9% for cross-validation and testing cohort, respectively) for every region. DL classification strongly agreed (accuracy = 91.0%, κ: 0.81) with expert visual assessment.ConclusionsDynamic volume rendering of the LV blood pool combined with DL classification can accurately detect regional WMA from cardiac CT.

Dataset Information

Mechanism of decreased sensitivity of dobutamine associated left ventricular wall motion analyses for appreciating inducible ischemia in older adults.

Publications

Mechanism of decreased sensitivity of dobutamine associated left ventricular wall motion analyses for appreciating inducible ischemia in older adults.

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