Assessment of cardiovascular physiology using dobutamine stress cardiovascular magnetic resonance reveals impaired contractile reserve in patients with cirrhotic cardiomyopathy.

BACKGROUND: Liver cirrhosis has been shown to affect cardiac performance. However cardiac dysfunction may only be revealed under stress conditions. The value of non-invasive stress tests in diagnosing cirrhotic cardiomyopathy is unclear. We sought to investigate the response to pharmacological stimulation with dobutamine in patients with cirrhosis using cardiovascular magnetic resonance. METHODS: Thirty-six patients and eight controls were scanned using a 1.5 T scanner (Siemens Symphony TIM; Siemens, Erlangen, Germany). Conventional volumetric and feature tracking analysis using dedicated software (CMR42; Circle Cardiovascular Imaging Inc, Calgary, Canada and Diogenes MRI; Tomtec; Germany, respectively) were performed at rest and during low to intermediate dose dobutamine stress. RESULTS: Whilst volumetry based parameters were similar between patients and controls at rest, patients had a smaller increase in cardiac output during stress (p = 0.015). Ejection fraction increase was impaired in patients during 10 µg/kg/min dobutamine as compared to controls (6.9 % vs. 16.5 %, p = 0.007), but not with 20 µg/kg/min (12.1 % vs. 17.6 %, p = 0.12). This was paralleled by an impaired improvement in circumferential strain with low dose (median increase of 14.4 % vs. 30.9 %, p = 0.03), but not with intermediate dose dobutamine (median increase of 29.4 % vs. 33.9 %, p = 0.54). There was an impaired longitudinal strain increase in patients as compared to controls during low (median increase of 6.6 % vs 28.6 %, p < 0.001) and intermediate dose dobutamine (median increase of 2.6%vs, 12.6 % p = 0.016). Radial strain response to dobutamine was similar in patients and controls (p > 0.05). CONCLUSION: Cirrhotic cardiomyopathy is characterized by an impaired cardiac pharmacological response that can be detected with magnetic resonance myocardial stress testing. Deformation analysis parameters may be more sensitive in identifying abnormalities in inotropic response to stress than conventional methods.

Noninvasive anatomical and functional assessment of coronary artery disease.

INTRODUCTION AND OBJECTIVE: In suspected coronary artery disease (CAD), invasive coronary angiography (ICA) is traditionally the diagnostic tool of choice. However, patients often have no significant disease. Moreover, assessment of fractional flow reserve (FFR) has been shown to have prognostic implications. Recently, coronary computed tomography angiography (CTA) and cardiac magnetic resonance (CMR) myocardial perfusion imaging (CMR-Perf) have gained increasing attention through their accurate anatomical and functional assessment, respectively. We studied the added value of integrating these tests (CT+CMRint) in the diagnosis of CAD, with FFR as the reference standard. METHODS: We included 101 patients consecutively referred for outpatient assessment of CAD who underwent CTA and CMR-Perf prior to ICA with FFR assessment. Lesions were considered positive by CT+CMRint only if positive in the two tests alone. The mean follow-up was 2.9±0.6 years. RESULTS: All patients completed the study protocol without adverse effects. Forty-four patients had CAD by FFR. CTA had excellent sensitivity and negative predictive value (100%) but, as expected, its specificity and positive predictive value were lower (61% and 67%, respectively). Diagnostic accuracy by FFR was 78% for CTA, 88% for CMR-Perf and 92% for CT+CMRint. Regarding diagnostic accuracy, CT+CMRint showed statistically significant superiority (AUC=0.917, 95% CI 0.845-0.963) compared with CTA (AUC=0.807, 95% CI 0.716-0.879, p=0.0057) or CMR-Perf (AUC=0.882, 95% CI 0.802-0.938, p=0.0398) alone. Regarding prediction of revascularization, the integrated protocol maintained its superior performance. CONCLUSIONS: CT+CMRint showed superior diagnostic accuracy and could thus lead to a considerable reduction in invasive procedures for CAD diagnosis, with less risk and greater patient comfort.

Anatomical versus functional assessment of coronary artery disease: direct comparison of computed tomography coronary angiography and magnetic resonance myocardial perfusion imaging in patients with intermediate pre-test probability.

Computed tomography coronary angiography (CTA) and cardiac magnetic resonance myocardial perfusion imaging (CMR-MPI) are state-of-the-art tools for noninvasive assessment of coronary artery disease (CAD). We aimed to compare the diagnostic accuracy of CTA and CMR-MPI for the detection of functionally relevant CAD, using invasive coronary angiography (XA) with fractional flow reserve (FFR) as a reference standard, and to evaluate the best protocol integrating these techniques for assessment of patients with suspected CAD. 95 patients (68 % men; 62 ± 8.1 years) with intermediate pre-test probability (PTP) of CAD underwent a sequential protocol of CTA, CMR-MPI and XA. Significant CAD was defined as >90 % coronary stenosis, 40-90 % stenosis with FFR ≤ 0.80 or left main stenosis ≥50 %. Prevalence of significant CAD was 43 %. CTA was more sensitive (100 %) but less specific (59 %) than CMR-MPI (88 and 89 %, respectively) for detection of significant CAD, with a strong trend for higher global diagnostic accuracy of CMR-MPI (88 vs. 77 %, p = 0.05). An integrated approach based on an initial CTA and subsequent referral to CMR-MPI of positive/inconclusive results had the best diagnostic performance (AUC 0.91). The direct referral to XA of patients with positive/inconclusive CTA performed worse than a selective approach based on CMR-MPI results (AUC 0.80 vs. 0.91, p = 0.005). In this intermediate PTP population, CMR-MPI showed a strong trend toward better performance compared to CTA for the assessment of functionally significant CAD. A combined protocol integrating coronary anatomy and function seems to be a very effective approach in the accurate diagnosis of CAD.