Girish Dwivedi

Increased left atrial volume index is an independent predictor of raised serum natriuretic peptide in patients with suspected heart failure but normal left ventricular ejection fraction : Implication for diagnosis of diastolic heart failure

Left atrial volume index (LAVI) is increasingly recognised as a relatively load‐independent marker of left ventricular (LV) filling pressures. We assessed the capacity of LAVI to predict LV diastolic dysfunction in comparison with N‐terminal pro B‐type natriuretic peptide (NTproBNP) in patients with suspected heart failure and a normal ejection fraction (EF).

Effects of Left Bundle-Branch Block on Cardiac Structure, Function, Perfusion, and Perfusion Reserve Implications for Myocardial Contrast Echocardiography Versus Radionuclide Perfusion Imaging for the Detection of Coronary Artery Disease

Background— We aimed to investigate the cardiac effects of left bundle-branch block (LBBB) using myocardial contrast echocardiography (MCE) to ascertain the value of MCE for detecting coronary artery disease (CAD) and to uncover the mechanism that affects the accuracy of single-photon emission computed tomography (SPECT) in these patients. Methods and Results— Sixty-three symptomatic LBBB patients (group A), 10 left ventricular ejection fraction–matched control subjects without LBBB and no CAD (group B), and 10 normal control subjects (group C) underwent resting echocardiography. Rest and vasodilator MCE and SPECT were undertaken in LBBB patients. Septal (SW) and posterior wall (PW) thickness, thickening, quantitative myocardial blood flow (MBF), and MBF reserve were measured. SW/PW thickness and percentage thickening ratios were lower (P<0.01 and P<0.05, respectively) in group A compared with both groups B and C, but resting SW/PW MBF and MBF reserve ratios were similar in all 3 groups. MBF reserve but not MBF was reduced in groups A and B (2.2±0.7 versus 2.2±0.2; P=0.98) compared with group C (3.1±0.5; P<0.01). SW thickness was an independent predictor (P=0.006) of SPECT perfusion defects in LBBB patients without CAD. MCE (92%) had a sensitivity similar to SPECT (92%); however, the specificity of MCE (95%) was superior (P<0.0001) to SPECT (47%) for the detection of CAD. Conclusions— Despite asymmetrical reduction in SW thickness and function, MBF is preserved and MBF reserve is homogeneously reduced in LBBB patients with left ventricular systolic dysfunction. Because of partial volume effects, the accuracy of SPECT for detecting CAD was significantly compromised compared with MCE in this patient cohort.

Cost Effectiveness of the B Type Natriuretic Peptide, Electrocardiography, and Portable Echocardiography for the Assessment of Patients from the Community with Suspected Heart Failure

To analyze the cost efficiency of guidelines proposed by the European Society of Cardiology for investigation of patients in the community with suspected heart failure (HF). The guidelines recommend electrocardiography (ECG) and/or measurement of N‐terminal pro B type natriuretic peptide (NTproBNP) prior to referral for echocardiography. Portable echocardiography is a new but validated technique for the evaluation of HF. Accordingly, 137 suspected HF patients (mean age 71±13 years) from the community underwent ECG and NTproBNP estimation prior to portable echocardiography. Cost effective analysis for ECG, NTproBNP, portable echocardiography and a combination of these; to define valvular heart disease, right ventricular dysfunction and left ventricular systolic and diastolic dysfunction were compared. The cost of abnormal NTproBNP followed by portable echocardiography, abnormal ECG followed by portable echocardiography and portable echocardiography alone for the detection per case of left ventricular systolic dysfunction were u2003€313, u2003€310, and u2003€296 respectively and that for detection per case of any of the aforementioned cardiac abnormalities were u2003€198, u2003€223, and u2003€170 respectively. Portable echocardiography alone for the assessment of suspected HF patients resulted in a cost reduction of up to u2003€1083 for the detection per case of cardiac abnormality. While a strategy where initial NTproBNP estimation is cost effective in detecting any causes of heart failure, portable echocardiography remains the most costeffective strategy to assess patients from the community with suspected heart failure.

Clinical benefits of contrast-enhanced echocardiography during rest and stress examinations

Despite the recent introduction of tissue harmonic imaging in echocardiography, 10-15% of patients have poor endocardial border definition. This may lead to erroneous assessment of regional and global left ventricular (LV) function or to further diagnostic imaging with another modality thus increasing the costs for the healthcare system. The recent development of second generation contrast echocardiography agents such as SonoVue has resulted in several studies showing the value of these agents to outline endocardium clearly, thereby improving assessment of LV function. The use of these contrast agents has also opened the possibility of automated and quantitative LV function assessment, making it more accurate and reproducible. Other major clinical uses of these contrast agents are evaluation of LV masses such as thrombus and tumors, and better definition of LV structure such as delineating LV aneurysm, pseudoaneurysm; and non-compaction of LV and apical cardiomyopathy. Furthermore, the use of these contrast agents during stress not only improved the assessment of wall motion but also made possible the evaluation of myocardial perfusion, thereby increasing diagnostic accuracy for the detection of coronary artery disease.

Improved prediction of outcome by contrast echocardiography determined left ventricular remodelling parameters compared to unenhanced echocardiography in patients following acute myocardial infarction

AIMSnContrast echocardiography has been shown to be a more accurate method of assessing left ventricular (LV) remodelling compared with unenhanced echocardiography after acute myocardial infarction (AMI). However, whether this translated into improved prediction of outcome is not known.nnnMETHODS AND RESULTSnAccordingly, a total of 89 consecutive patients undergoing contrast echocardiography and unenhanced echocardiography 7 to 10 days after AMI and reperfusion therapy were followed up for cardiac death (CD) and AMI. LV ejection fraction (LVEF), LV end-systolic volume (ESV), and LV end-diastolic volume were assessed by the two methods independently. Outcome data were obtained (mean 46 +/- 16 months).There were 15 (17%) events (eight CDs and seven AMIs). LVEF and ESV with contrast echocardiography were found to be independent multivariable predictors of CD (P = 0.04 and P = 0.02, respectively) and CD or AMI (P = 0.02 and P = 0.01, respectively). Furthermore, LVEF and ESV with contrast echocardiography provided incremental information for the prediction of CD (P = 0.004 and P = 0.004, respectively) and CD or AMI (P = 0.02 and P = 0.03, respectively).nnnCONCLUSIONnContrast echocardiography provided improved prediction of outcome compared with unenhanced echocardiography following AMI.

Comparison Between Myocardial Contrast Echocardiography and 99mTechnetium Sestamibi Single Photon Emission Computed Tomography Determined Myocardial Viability in Predicting Hard Cardiac Events Following Acute Myocardial Infarction

The extent of residual myocardial viability (MV) after acute myocardial infarction (AMI) is an important determinant of the outcome. Single photon emission computed tomography (SPECT) is widely used to assess MV after an AMI. However, myocardial contrast echocardiography (MCE), a relatively new technique for the assessment of MV, has better spatial and temporal resolution than SPECT. The present study evaluated whether MV determined by MCE is comparable to that determined using SPECT for the prediction of hard cardiac events after an AMI. Accordingly, 99 patients who had undergone simultaneous rest low-power MCE and nitrate-enhanced SPECT 7 days after an AMI were followed up for cardiac death and AMIs. Both MCE perfusion (1 = normal; 2 = reduced; and 3 = absent) and SPECT tracer uptake (0 = normal; 1 = mildly reduced; 2 = moderately reduced; 3 = severely reduced; and 4 = absent) were scored on a 16-segment left ventricular model. The contrast perfusion index and SPECT perfusion index were calculated by adding the respective scores in the 16 segments and dividing by 16. The contrast perfusion index and SPECT perfusion index were used as a measure of the residual MV on MCE and SPECT, respectively. Of the 99 patients recruited, 95 were available for the follow-up examination (follow-up 46 +/- 16 months). A total of 15 events (16%) occurred (8 cardiac deaths and 7 AMIs). Of the clinical, biochemical, echocardiographic, and SPECT markers of prognosis, the only independent predictors of cardiac death and cardiac death or AMI were age and MV as determined by MCE (p = 0.01 and p = 0.002, respectively). In conclusion, MV determined by MCE at rest was superior to nitrate-enhanced SPECT for the prediction of hard cardiac events after AMI.

Relationship between myocardial perfusion with myocardial contrast echocardiography and function early after acute myocardial infarction for the prediction of late recovery of function

BACKGROUNDnFollowing ST elevation acute myocardial infarction (STEMI) and reperfusion therapy, there are often persistent wall thickening (WT) abnormalities and perfusion defects due to variable degree of myocardial stunning and necrosis. We hypothesised that following STEMI and reperfusion therapy, the extent of residual perfusion assessed by myocardial contrast echocardiography (MCE) and not the extent of WT abnormalities would predict subsequent global recovery of left ventricular (LV) function.nnnMETHODSnAccordingly, 112 patients with STEMI underwent simultaneous assessment of WT abnormality and perfusion using MCE 7+/-2 days after AMI and reperfusion therapy. Both WT and perfusion were scored on a 16 segment LV model. Contrast perfusion index (CPI), and global LV function were calculated. Echocardiography was repeated 12 weeks after reperfusion to assess recovery of LV function.nnnRESULTSnOf the 112 patients recruited, follow up echocardiography 12 weeks after reperfusion was available in 98 patients. CPI was significantly higher (p<0.0001) in the 66 patients, who showed late recovery of LV function (1.67+/-0.27) compared to those who did not show recovery of function (1.25+/-0.04). No significant difference was noted in the indices of baseline LV function in patients with (1.67+/-0.32) and without (1.80+/-0.36) recovery of LV function. The multivariable predictors of late recovery of function were MCE (p=0.02), absence of diabetes (p=0.02) and lower peak creatine kinase (p=0.01).nnnCONCLUSIONnThe extent of residual contrast perfusion and not WT abnormalities predicts late recovery of global LV function after acute myocardial infarction and reperfusion therapy.

Myocardial contrast echocardiography: Role in clinical cardiology.

Recent updates in the field of echocardiography have resulted in improvements in both image quality and techniques allowing echocardiography to maintain its position as the primary non-invasive imaging modality. In particular, the development of new ultrasound contrast agents and imaging techniques have now made possible the assessment of myocardial perfusion. Myocardial contrast echocardiography utilises acoustically active gas filled microspheres (microbubbles), which have rheology similar to that of red blood cells. The detection of myocardial perfusion during echocardiographic examinations permits simultaneous assessment of global and regional myocardial structure, function, and perfusion, enabling the optimal non-invasive assessment of coronary artery disease. Myocardial contrast echocardiography is equally adept in assessing chronic coronary artery disease as well as acute coronary syndromes. Furthermore, its use is not limited solely to diagnostic assessment. Preliminary evidence suggests that targeted microbubbles may be useful in enhancing delivery of genes / drugs and in clot lysis.

Contrast dobutamine stress myocardial perfusion echocardiography: current methodology and clinical applications

Accurate evaluation of regional systolic wall thickening by echocardiography is largely dependent on adequate endocardial border resolution. Despite the recent introduction of tissue harmonic imaging, 15-20% of patients have poor endocardial border definition. Even with the use of ultrasonic contrast agents and resulting improvement in the endocardial delineation, conventional dobutamine stress echocardiography, though it has a high sensitivity for the diagnosis of coronary artery disease in patients with multivessel disease on coronary angiography, has limited ability to diagnose multivessel disease on the basis of inducible wall motion abnormalities in multivessel distributions. As in the ischemic cascade during demand stress myocardial perfusion abnormalities precede wall motion abnormalities, techniques which image myocardial perfusion as compared to wall motion are able to detect functionally significant coronary artery disease at an earlier stage and potentially at a submaximal stress. With real time myocardial perfusion imaging it is possible to simultaneously assess myocardial perfusion and function not only at rest but also during stress, which makes it a sensitive technique to detect and risk- stratify flow limiting coronary artery disease as compared to conventional wall motion imaging during stress. Furthermore, it has now become feasible to assess the changes in myocardial blood flow that occur during stress testing with the availability of softwares which makes it possible to quantitatively analyse these images, potentially improving the sensitivity and specificity of contrast echocardiography even further.