Physical and Physiologic Effects of Dobutamine Stress Echocardiography in Low-Gradient Aortic Stenosis

Background: Dobutamine stress echocardiography (DSE) is a useful tool for assessing low-gradient significant aortic stenosis (AS) and contractile reserve (CR), but its prognostic utility has become controversial in recent studies. We evaluated the impact of DSE on aortic valve physiological, structural and left ventricular parameters in low gradient AS. Methods: Consecutive patients undergoing DSE for low-gradient AS evaluation from September 2010 to July 2016 were retrospectively studied, and DSE findings divided into four groups with and without severe AS and CR. Relationships between left ventricular chamber quantification, CR, aortic valve Doppler during DSE and calcium score (by CT) were analysed. Results: There were 258 DSE studies performed on 243 patients, mean age 77.6±10.8 years and 183 (70.1%) were male. With increasing dobutamine dose, apart from systolic blood pressure, left ventricular ejection fraction, flow, cardiac power output and longitudinal strain magnitude, along with aortic valve area and mean aortic gradient all significantly increased (P<0.05). Flow and mean gradient increased in both the presence and absence of CR, whereas stroke volume and aortic valve area increased mainly in those with CR only. The aortic valve area increased in both patients with low and high calcium score, however the baseline area was lower in those with a higher calcium score. Conclusion: During DSE, aortic valve area increases with increase aortic valve gradient. Higher calcium score is associated with lower baseline aortic valve area, but the area valve area still increases with dobutamine even in presence of high calcium score.

Predictive Value of Cardiac Magnetic Resonance Feature Tracking after Acute Myocardial Infarction: A Comparison with Dobutamine Stress Echocardiography

In acute ST-segment elevation myocardial infarction (STEMI) late gadolinium enhancement (LGE) may underestimate segmental functional recovery. We evaluated the predictive value of cardiac magnetic resonance (CMR) feature-tracking (FT) for functional recovery and whether it incremented the value of LGE compared to low-dose dobutamine stress echocardiography (LDDSE) and speckle-tracking echocardiography (STE). Eighty patients underwent LDDSE and CMR within 5–7 days after STEMI and segmental functional recovery was defined as improvement in wall-motion at 6-months CMR. Optimal conventional and FT parameters were analyzed and then also applied to an external validation cohort of 222 STEMI patients. Circumferential strain (CS) was the strongest CMR-FT predictor and addition to LGE increased the overall accuracy to 74% and was especially relevant in segments with 50–74% LGE (AUC 0.60 vs. 0.75, p = 0.001). LDDSE increased the overall accuracy to 71%, and in the 50–74% LGE subgroup improved the AUC from 0.60 to 0.69 (p = 0.039). LGE + CS showed similar value as LGE + LDDSE. In the validation cohort, CS was also the strongest CMR-FT predictor of recovery and addition of CS to LGE improved overall accuracy to 73% although this difference was not significant (AUC 0.69, p = 0.44). Conclusion: CS is the strongest CMR-FT predictor of segmental functional recovery after STEMI. Its incremental value to LGE is comparable to that of LDDSE whilst avoiding an inotropic stress agent. CS is especially relevant in segments with 50–74% LGE where accuracy is lower and further testing is frequently required to clarify the potential for recovery.

USE OF DOBUTAMINE STRESS ECHOCARDIOGRAPHY TO ASSESS MYOCARDIAL VIABILITY BEFORE PCI IN TOTAL OCCLUSION OF CORONARY ARTERY IN A TERTIARY CARE CENTRE

Dobutamine stress echocardiography has significant advantages in our country due to its wide availability, portability, low cost and safety.This study was conducted with the aim to assess myocardial viability by Dobutamine Stress Echocardiography (DSE) before PCI in total occlusion of coronary artery.This study confirms that a biphasic response to dobutamine is highly predictive of postoperative recovery of regional contractile function (100% at 6th week follow-up). This studies provide evidence that, at low doses, inotropic stimulation with P- receptor agonists will result in an increase in LV function in areas of viable myocardium but not in areas of myocardial necrosis.