J. J. Bax

Assessing right ventricular function: the role of echocardiography and complementary technologies

The physiological importance of the right ventricle (RV) has been underestimated; the RV was considered mainly as a conduit whereas its contractile performance was thought to be haemodynamically unimportant.1 However, its essential contribution to normal cardiac pump function is well established with the primary RV functions being: RV function may be impaired either by primary right sided heart disease, or secondary to left sided cardiomyopathy or valvar heart disease.2 In addition, it should be considered that RV dysfunction may affect left ventricular (LV) function, not only by limiting LV preload, but also by adverse systolic and diastolic interaction via the intraventricular septum and the pericardium (ventricular interdependence). Moreover, RV function has been shown to be a major determinant of clinical outcome3–9 and consequently should be considered during clinical management and treatment.10 Thus, the need for diagnosis of RV dysfunction is evident. In practice, clinicians largely rely on non-invasive imaging methods for assessment of RV function. Two dimensional echocardiography is the mainstay for analysis of RV function, but recently alternative techniques have been proposed, including tissue Doppler imaging (TDI) techniques,11 three dimensional echocardiography,12 magnetic resonance imaging (MRI), and even invasive assessment of pressure–volume loops.13–17 An overview of these imaging modalities for assessment of RV function is provided in the current manuscript. Due to its widespread availability, echocardiography is used as the first line imaging modality for assessment of RV size and RV function. The quantitative assessment of RV size and function is often difficult, because of the complex anatomy. Nevertheless, when used …

Prevalence of coronary artery disease and plaque morphology assessed by multi-slice computed tomography coronary angiography and calcium scoring in asymptomatic patients with type 2 diabetes

Objective: The purpose of the study was to evaluate the prevalence of CAD as well as plaque morphology in asymptomatic patients with type 2 diabetes using multi-slice computed tomography (MSCT). In addition, the relation between calcium score and MSCT findings was explored. Design: In 70 patients, coronary calcium scoring and non-invasive coronary angiography were performed. Angiograms showing atherosclerosis were further classified as obstructive (⩾50% luminal narrowing) CAD or not. Plaque type (non-calcified, mixed and calcified) was determined. Finally, the relation between calcium score and MSCT findings was explored. Results: A calcium score <10 was observed in 31 (44%) patients. A calcium score of 10–100 was observed in 14 (20%) patients while a score of 101–400 or >400 was identified in 12 (17%) and 13 (19%) patients respectively. Non-invasive coronary angiography showed CAD in 56 (80%) patients. 322 coronary segments with plaque were identified, of which 132 (41%) contained non-calcified plaques, 65 (20%) mixed plaques and 125 (39%) calcified plaques. The percentage of patients with obstructive CAD paralleled increasing calcium score. The presence of CAD was noted in 17 (55%) patients with no or minimal calcium (score <10). Conclusions: MSCT angiography detected a high prevalence of CAD in asymptomatic patients with type 2 diabetes. A relatively high proportion of plaques were non-calcified (41%). Importantly, a calcium score <10 did not exclude CAD in these patients. MSCT might be a useful technique to identify CAD in asymptomatic patients with type 2 diabetes with incremental value over calcium scoring.

Differences in plaque composition and distribution in stable coronary artery disease versus acute coronary syndromes; non‐invasive evaluation with multi‐slice computed tomography

Background: Plaque composition rather than degree of luminal narrowing may be predictive of acute coronary syndromes (ACS). The purpose of the study was to compare plaque composition and distribution with multi‐slice computed tomography (MSCT) between patients presenting with either stable coronary artery disease (CAD) or ACS. Methods: MSCT was performed in 22 and 24 patients presenting with ACS or stable CAD, respectively. Coronary lesions were classified as calcified, non‐calcified or mixed while signal intensity (SI) was measured. Results: In patients with stable CAD, the majority of lesions were calcified (89%). In patients with ACS, less calcifications were observed with a greater proportion of non‐calcified (18%) or mixed (36%) lesions (P<0.001). Accordingly, mean SI of plaques was significantly less in ACS (320±201 HU versus 620±256 HU in stable CAD, P<0.001). Dividing lesions in the ACS group according to culprit versus non‐culprit vessel location resulted in no significant difference in average SI between these two groups while still lower as compared to stable CAD (P<0.001). Conclusions: In patients with ACS, significantly less calcifications were present as compared to stable CAD. Moreover, even in non‐culprit vessels, multiple non‐calcified plaques were detected, indicating diffuse rather than focal atherosclerosis in ACS.

Radionuclide techniques for the assessment of myocardial viability and hibernation

Over the past decade the number of patients presenting with heart failure has increased exponentially.1 It has been estimated that 4.7 million patients in the USA have chronic heart failure, with 400 000 new cases per year, resulting in one million hospitalisations.1 The diagnostic and therapeutic costs involved with heart failure are estimated to be more than

Cardiac imaging in coronary artery disease: differing modalities

11 billion per year.1 Gheorghiade and Bonow emphasised that the aetiology of heart failure may be coronary artery disease in > 70% of patients.2 Currently, three routine courses of action are available: medical treatment, heart transplantation, and revascularisation. Newer therapeutic modalities include laser therapy, advanced surgery, assist devices, artificial hearts,3 and transplantation of different (progenitor) cells.4 These options should currently be considered experimental but may offer alternative treatments in the future. Medical treatment has improved substantially over the past years, with the introduction of angiotensin converting enzyme (ACE) inhibitors, angiotensin II receptor blockers, and spironolactone. Four recent trials have demonstrated the value of β adrenergic blocking agents in the treatment of patients with heart failure.5 Finally, amiodarone has been demonstrated to reduce sudden death in patients with heart failure.6 Despite all of these new drugs, mortality of patients with severe heart failure remains high; Cowie and colleagues7 reported 12 month mortality to be 38% and extrapolation of these results demonstrated five year mortality to be > 70%. The second option, heart transplantation, has fairly good long term prognosis but the limited number of donor hearts is largely exceeded by demand.8 In addition, many patients with heart failure have significant co-morbidities, excluding them as candidates for heart transplantation. Revascularisation is the third option in patients with heart failure. The major drawback to performing revascularisation in these patients is the high periprocedural morbidity and mortality. …

Cardiac resynchronisation therapy in chronic atrial fibrillation: impact on left atrial size and reversal to sinus rhythm

Coronary artery disease (CAD) remains one of the leading causes of morbidity and mortality worldwide. Moreover, the disease is reaching endemic proportions and will put an enormous strain on health care economics in the near future. Non-invasive testing is important to exclude CAD with a high certainty on the one hand, and to detect CAD with its functional consequences at an early stage, to guide optimal patient management, on the other hand. For these purposes, non-invasive imaging techniques have been developed and used extensively over the last years. Currently, the main focus of non-invasive imaging for diagnosis of CAD is twofold: (1) functional imaging , assessing the haemodynamic consequences of obstructive coronary artery disease; and (2) anatomical imaging , visualising non-invasively the coronary artery tree. For functional imaging, nuclear cardiology, stress echocardiography, and magnetic resonance imaging (MRI) are used, whereas for anatomical imaging or non-invasive angiography, MRI, multislice CT (MSCT), and electron beam CT (EBCT) are used. This manuscript will update the reader on the current status of non-invasive imaging, with a special focus on functional imaging versus anatomical imaging for the detection of CAD. The accuracies of the different imaging modalities are illustrated using pooled analyses of the available literature data when available. ### What information does functional imaging provide? The hallmark of functional imaging is the detection of CAD by assessing the haemodynamic consequences of CAD rather than by direct visualisation of the coronary arteries. For this purpose, regional perfusion or wall motion abnormalities are induced (or worsened) during stress, reflecting the presence of stress induced ischaemia. Ischaemia induction is based on the principle that although resting myocardial blood flow in regions supplied by stenotic coronary arteries is preserved, the increased flow demand during stress cannot be met, resulting in a sequence of events referred to as “the ischaemic cascade”.1 Initially perfusion abnormalities are …

Gender influence on the diagnostic accuracy of 64-slice multislice computed tomography coronary angiography for detection of obstructive coronary artery disease

Objective: To evaluate the impact of long term cardiac resynchronisation therapy (CRT) on left atrial and left ventricular (LV) reverse remodelling and reversal to sinus rhythm (SR) in patients with heart failure with atrial fibrillation (AF). Patients: 74 consecutive patients (age 68 (8) years; 67 men) with advanced heart failure and AF (20 persistent and 54 permanent) were implanted with a CRT device. Main outcome measures: Patients were evaluated clinically (New York Heart Association (NYHA) class, quality of life, six minute walk test) and echocardiographically (LV ejection fraction, LV diameters, and left atrial diameters) before and after six months of CRT. Additionally, restoration of SR was evaluated after six months of CRT. Results: NYHA class, quality of life score, six minute walk test, and LV ejection fraction had improved significantly after six months of CRT. In addition, left atrial and LV end diastolic and end systolic diameters had decreased from 59 (9) to 55 (9) mm, from 72 (10) to 67 (10) mm, and from 61 (11) to 56 (11) mm, respectively (all p < 0.01). During implantation 18 of 20 (90%) patients with persistent AF were cardioverted to SR. At follow up 13 of 18 (72%) patients had returned to AF and none had spontaneously reverted to SR; thus, only 5 of 74 (7%) were in SR. Conclusion: Six months of CRT resulted in significant clinical benefit with significant left atrial and LV reverse remodelling. Despite these beneficial effects, 93% of patients had not reverted to SR.

Echocardiographic evaluation of cardiac dyssynchrony for predicting a favourable response to cardiac resynchronisation therapy

Objective: To compare the diagnostic accuracy of 64-slice multislice computed tomography (MSCT) coronary angiography between female and male patients using conventional coronary angiography as the reference standard. Design: Diagnostic accuracy study. Setting: University hospital. Patients: 103 consecutive patients (51 men, 52 women, mean (SD) age 60 (10) years) with known and suspected coronary artery disease underwent 64-slice MSCT. Main outcome measures: Diagnostic accuracy of 64-slice MSCT to detect obstructive (⩾50% luminal narrowing) stenoses in men and women. Results: One male and two female patients were excluded from the analysis owing to non-diagnostic MSCT scans as a result of increased heart rate and breathing during the scan. Accordingly, on segmental level, 728/762 coronary segments were of sufficient quality in women (96% (95% CI 95% to 97%)) and 704/723 segments were interpretable in men (97% (95% CI 96% to 98%)). In the remaining 100 patients included in the further analyses, the sensitivity and specificity on a segmental level in women and men were 85% (95% CI 75% to 95%) vs 85% (95% CI 78% to 92%) and 99% (95% CI 98% to 100%) vs 99% (95% CI 98% to 100%), respectively. On a patient level, the sensitivity in women and men was 95% (95% CI 87% to 100%) vs 100%, specificity 93% (95% CI 83% to 100%) vs 89% (95% CI 74% to 100%), positive predictive value 91% (95% CI 79% to 100%) vs 94% (95% CI 86% to 100%), and negative predictive value 96% (95% CI 89% to 100%) vs 100%, respectively. Conclusion: The findings confirm the high diagnostic accuracy of 64-slice MSCT coronary angiography in both male and female patients.

Comprehensive cardiac assessment with multislice computed tomography: evaluation of left ventricular function and perfusion in addition to coronary anatomy in patients with previous myocardial infarction

Cardiac resynchronisation therapy (CRT) is an established therapy for patients with heart failure with wide QRS duration. Recent studies observed that assessment of systolic dyssynchrony is an important diagnostic tool as the treatment involves the re-coordination of regional wall contraction within the left ventricle. Therefore, the effectiveness of CRT depends heavily on whether systolic dyssynchrony is present before the treatment. Echocardiography is a useful tool for quantitative measurement of the severity of dyssynchrony in these patients before and after CRT. A number of echocardiographic tools have been developed during the past three years for such purpose, include M mode measurement of septal-to-posterior wall delay, tissue Doppler imaging for septal-to-lateral wall delay, the measurement of standard deviation of peak contraction time over 12 left ventricular segments, delayed longitudinal contraction, and potentially three dimensional echocardiography. This review discusses the potential role of various echocardiographic techniques in the assessment of systolic dyssynchrony and their clinical applications.

Anatomical and functional imaging techniques: basically similar or fundamentally different?

Objective: To evaluate a comprehensive multislice computed tomography (MSCT) protocol in patients with previous infarction, including assessment of coronary artery stenoses, left ventricular (LV) function and perfusion. Patients and methods: 16-slice MSCT was performed in 21 patients with previous infarction; from the MSCT data, coronary artery stenoses, (regional and global) LV function and perfusion were assessed. Invasive coronary angiography and gated single-photon emission computed tomography (SPECT) served as the reference standards for coronary artery stenoses and LV function/perfusion, respectively. Results: 236 of 241 (98%) coronary artery segments were interpretable on MSCT. The sensitivity and specificity for detection of stenoses were 91% and 97%. Pearson’s correlation showed excellent agreement for assessment of LV ejection fraction between MSCT and SPECT (49 (13)% v 53 (12)%, respectively, r  =  0.85). Agreement for assessment of regional wall motion was excellent (92%, κ  =  0.77). In 68 of 73 (93%) segments, MSCT correctly identified a perfusion defect as compared with SPECT, whereas the absence of perfusion defects was correctly detected in 277 of 284 (98%) segments. Conclusions: MSCT permits accurate, non-invasive assessment of coronary artery stenoses, LV function and perfusion in patients with previous infarction. All parameters can be assessed from a single dataset.