Iain D.C. Kirkpatrick

Role of Three-Dimensional Echocardiography in Breast Cancer: Comparison With Two-Dimensional Echocardiography, Multiple-Gated Acquisition Scans, and Cardiac Magnetic Resonance Imaging

PURPOSE In patients with breast cancer, the administration of doxorubicin and trastuzumab is associated with an increased risk of cardiotoxicity. Although multiple-gated acquisition (MUGA) scans and two-dimensional transthoracic echocardiography (TTE) are conventional methods for baseline and serial assessment of left ventricular ejection fraction (LVEF) in these patients, little is known about the use of real-time three-dimensional TTE (RT3D TTE) in this clinical setting. The aim of this study was to assess the accuracy of MUGA, 2D TTE, and RT3D TTE for determining LVEF in comparison to cardiac magnetic resonance imaging (CMR). METHODS Between 2007 and 2009 inclusive, 50 female patients with human epidermal growth factor receptor 2-positive breast cancer received adjuvant trastuzumab after doxorubicin. Serial MUGA, 2D TTE, RT3D TTE, and CMR were performed at baseline, 6, and 12 months after the initiation of trastuzumab. RESULTS A comparison of left ventricular end diastolic volume (LVEDV) demonstrated a modest correlation between 2D TTE and CMR (r = 0.64 at baseline; r = 0.69 at 12 months, respectively). A comparison of LVEDV between RT3D TTE and CMR demonstrated a stronger correlation (r = 0.87 at baseline; r = 0.95 at 12 months, respectively). Although 2D TTE demonstrated a weak correlation with CMR for LVEF assessment (r = 0.31 at baseline, r = 0.42 at 12 months, respectively), both RT3D TTE and MUGA showed a strong correlation when compared with CMR (r = 0.91 at baseline; r = 0.90 at 12 months, respectively). CONCLUSION As compared with conventional MUGA, RT3D TTE is a feasible, accurate, and reproducible alternate imaging modality for the serial monitoring of LVEF in patients with breast cancer.

Obstructive Sleep Apnea : Effects of Continuous Positive Airway Pressure on Cardiac Remodeling as Assessed by Cardiac Biomarkers, Echocardiography, and Cardiac MRI

BACKGROUND Obstructive sleep apnea (OSA) is associated with an increased risk of cardiovascular morbidity and mortality. Although previous echocardiographic studies have demonstrated short-term improvement in cardiovascular remodeling in patients with OSA receiving continuous positive airway pressure (CPAP) therapy, a long-term study incorporating cardiac biomarkers, echocardiography, and cardiac MRI (CMR) has not been performed to date. METHODS A prospective study of 47 patients with OSA was performed between 2007 and 2010. Cardiac biomarkers, including C-reactive protein (CRP), N-terminal pro-B-type natriuretic peptide (NT-proBNP), and troponin T (TnT), were measured at baseline and serially over 1 year. All patients underwent baseline and serial transthoracic echocardiography (TTE) and CMR to assess cardiac remodeling. RESULTS Following 12 months of CPAP therapy, levels of CRP, NT-proBNP, and TnT did not change significantly from normal baseline values. As early as 3 months after initiation of CPAP, TTE revealed an improvement in right ventricular end-diastolic diameter, left atrial volume index, right atrial volume index, and degree of pulmonary hypertension, which continued to improve over 1 year of follow-up. Finally, left ventricular mass, as determined by CMR, decreased from 159 ± 12 g/m(2) to 141 ± 8 g/m(2) as early as 6 months into CPAP therapy and continued to improve until completion of the study at 1 year. CONCLUSION Both systolic and diastolic abnormalities in patients with OSA can be reversed as early as 3 months into CPAP therapy, with progressive improvement in cardiovascular remodeling over 1 year as assessed by both TTE and CMR.

Delayed contrast enhancement cardiac magnetic resonance imaging in trastuzumab induced cardiomyopathy

BackgroundTrastuzumab (Herceptin), an antagonist to the human epidermal growth factor 2 (HER2) receptor significantly decreases the rates of breast cancer recurrence and mortality by 50%. Despite therapeutic benefits, the risk of cardiotoxicity with trastuzumab ranges from 10–15% when administered sequentially following anthraycline chemotherapy. Little is known about the utility of cardiac magnetic resonance (CMR) in the assessment of trastuzumab mediated cardiomyopathy.Methods and resultsBetween 2005–2006 inclusive, 160 breast cancer patients were identified at a single tertiary care oncology centre. Of the total population, 10 patients (mean age 40 ± 8 years) were identified with trastuzumab induced cardiomyopathy, based on a LVEF less than 40% on serial MUGA or echocardiography. CMR was performed in all patients to determine LV volumes, systolic function and evidence of late gadolinium enhancement (LGE). At the time of diagnosis of trastuzumab induced cardiomyopathy, the mean LVEF was 29 ± 4%. Subepicardial linear LGE was present in the lateral portion of the left ventricles in all 10 patients.ConclusionLGE-CMR is a novel way of detecting early changes in the myocardium due to trastuzumab induced cardiotoxicity.

The impact of repeated marathon running on cardiovascular function in the aging population

BackgroundSeveral studies have correlated elevations in cardiac biomarkers of injury post marathon with transient and reversible right ventricular (RV) systolic dysfunction as assessed by both transthoracic echocardiography (TTE) and cardiovascular magnetic resonance (CMR). Whether or not permanent myocardial injury occurs due to repeated marathon running in the aging population remains controversial.ObjectivesTo assess the extent and severity of cardiac dysfunction after the completion of full marathon running in individuals greater than 50 years of age using cardiac biomarkers, TTE, cardiac computed tomography (CCT), and CMR.MethodsA total of 25 healthy volunteers (21 males, 55 ± 4 years old) from the 2010 and 2011 Manitoba Full Marathons (26.2 miles) were included in the study. Cardiac biomarkers and TTE were performed one week prior to the marathon, immediately after completing the race and at one-week follow-up. CMR was performed at baseline and within 24 hours of completion of the marathon, followed by CCT within 3 months of the marathon.ResultsAll participants demonstrated an elevated cTnT post marathon. Right atrial and ventricular volumes increased, while RV systolic function decreased significantly immediately post marathon, returning to baseline values one week later. Of the entire study population, only two individuals demonstrated late gadolinium enhancement of the subendocardium in the anterior wall of the left ventricle, with evidence of stenosis of the left anterior descending artery on CCT.ConclusionsMarathon running in individuals over the age of 50 is associated with a transient, yet reversible increase in cardiac biomarkers and RV systolic dysfunction. The presence of myocardial fibrosis in older marathon athletes is infrequent, but when present, may be due to underlying occult coronary artery disease.

The Role of Three-Dimensional Echocardiography in the Assessment of Right Ventricular Dysfunction after a Half Marathon: Comparison with Cardiac Magnetic Resonance Imaging

BACKGROUND Although marathon running is associated with transient right ventricular (RV) systolic dysfunction as detected by two-dimensional transthoracic echocardiography, quantitative assessment of the right ventricle is difficult because of its complex geometry. Little is known about the use of real-time three-dimensional echocardiography (RT3DE) in the detection of cardiac dysfunction after a half marathon. The aim of this study was to assess the extent of RV dysfunction after the completion of a half marathon using cardiac biomarkers, RT3DE, and cardiac magnetic resonance imaging (CMR). METHODS A prospective study was performed in 15 individuals in 2009 participating in the Manitoba Half Marathon. Cardiac biomarkers (myoglobin, creatine kinase-MB and cardiac troponin T) were assessed and RT3DE and CMR were performed 1 week before, immediately after, and 1 week after the race. RESULTS At baseline, cardiac biomarkers and ventricular function were within normal limits. Immediately following the half marathon, all patients demonstrated elevated cardiac troponin T levels, with a median value of 0.37 ng/mL. RV ejection fraction, as assessed by RT3DE, decreased from 59 ± 4% at baseline to 45 ± 5% immediately following the race (P < .05). On CMR, RV end-diastolic volume increased after the half marathon, and the RV ejection fraction was reduced, at 47 ± 5% compared with 60 ± 2% at baseline (P < .05). There were strong linear correlations between RV ejection fraction assessed by RT3DE and CMR at baseline and after the half marathon (r = 0.69 and r = 0.87, P < .01, respectively). CONCLUSIONS Compared with CMR, RT3DE is a feasible and reproducible method of assessing transient RV dysfunction in athletes completing a half marathon.

Utility of Balanced Steady-State Free Precession MR Venography in the Diagnosis of Lower Extremity Deep Venous Thrombosis

OBJECTIVE The purpose of this study was to determine the sensitivity and specificity of balanced steady-state free precession MR venography in the diagnosis of lower extremity deep venous thrombosis. SUBJECTS AND METHODS After undergoing lower extremity ultrasound because of suspicion of deep venous thrombosis, 64 patients were prospectively recruited to undergo balanced steady-state free precession MR venography with ultrasound as the reference standard. Ultrasound images were independently interpreted by two blinded ultrasound radiologists, and MR venograms were independently interpreted by two blinded MRI radiologists. The sensitivity, specificity, positive predictive value, and negative predictive value of MR venography were calculated for the diagnoses of all deep venous thrombosis, acute thrombi, and thrombosis of the popliteal, femoral, and common femoral veins individually. Proximal extent, thrombus age, ancillary findings, and interobserver agreement calculated with the Cohen kappa test were evaluated for ultrasound and MRI. The McNemar test was used to evaluate for statistical differences in diagnostic accuracy. RESULTS MR venography had a sensitivity of 94.7%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 97.7% for the diagnosis of all thrombi. For acute thrombi, the MR venography and ultrasound results were completely concordant. MR venography depicted greater proximal extent in five of 18 cases in which thrombosis was found. The MR venographic findings agreed completely with the ultrasound findings in determination of thrombus age. For both ultrasound and MR venography, interobserver agreement was 100% on a per-patient basis. No statistical difference was identified in the diagnostic performance of the two techniques. CONCLUSION Balanced steady-state free precession MR venography is highly accurate in the diagnosis of lower extremity deep venous thrombosis.

The utility of cardiovascular magnetic resonance in constrictive pericardial disease.

Cardiovascular magnetic resonance (CMR) has a high diagnostic accuracy for constrictive pericarditis (CP). CMR allows for high-resolution imaging of the pericardium and associated structures in any imaging plane compared with that provided by other imaging modalities. We briefly discuss the specific quantitative and qualitative CMR sequences that can be tailored to answer the clinical questions pertaining to CP, where the diagnostic yield has been proven when characteristic CMR features of CP are present. Such features allow for differentiation of CP from restrictive cardiomyopathy, where the clinical differentiation between the 2 can often be challenging.

The ‘what, when, where, who and how?’ of cardiac computed tomography in 2009: Guidelines for the clinician

DISCLOSURES: Benjamin Chow is supported by the Canadian Institutes of Health Research New Investigator Award #MSH-83718. He receives research and fellowship support from GE Healthcare, and education support from TeraRecon, Inc. Arun Abraham is supported by the Heather and Whit Tucker Research Fellowship in Cardiology. The remaining authors have no conflicts of interest to disclose.

Vocal Cord Paralysis After Thoracic Aortic Surgery: Incidence and Impact on Clinical Outcomes

BACKGROUND Vocal cord paralysis (VCP) is a serious complication associated with thoracic aortic surgery; however, there is a paucity of literature regarding the incidence and impact of VCP on postoperative outcomes. We sought to determine the incidence of VCP and its impact on clinical outcomes in patients who underwent thoracic aortic repair at our center. METHODS A retrospective chart review was conducted on all patients who underwent thoracic aortic surgery between January 2009 and September 2012. RESULTS A total of 259 patients underwent a thoracic aortic procedure during the study period. Vocal cord paralysis was diagnosed in 12 (5%) patients, a median of 6 [3 to 21] days after extubation. The incidence was 1%, 0%, 20%, and 25% in those undergoing an open ascending, hemiarch, total arch, or descending aortic procedure, respectively. Patients with VCP had an increased incidence of pneumonia (58% vs 17%, p = 0.003), readmission to the intensive care unit for respiratory failure (17% vs 2%, p = 0.047), and longer hospital length of stay (18 [11 to 43] days versus 9 [6 to 15] days, p = 0.002). A propensity-matched analysis confirmed a higher incidence of pneumonia (58% vs 17%, p = 0.020) and longer hospital length of stay (18 [11 to 43] vs 10 [7 to 14] days, p = 0.015) in patients suffering VCP. CONCLUSIONS Vocal cord paralysis is a common complication in patients undergoing open surgery of the aortic arch and descending aorta, and is associated with significant morbidity. Further research may be warranted to determine if early fiberoptic examination and consideration of a vocal cord medialization procedure may mitigate the morbidity associated with VCP.

Spontaneous dissection of the coronary and vertebral arteries post-partum: case report and review of the literature

BackgroundSpontaneous coronary and vertebral artery dissections are rare events occurring most commonly in otherwise healthy women during pregnancy or the post-partum period.Case presentationThis report describes a 35-year-old female who presented with an acute inferior ST elevation myocardial infarction 7 months post-partum secondary to spontaneous dissection of the left obtuse marginal coronary artery. Despite appropriate medical therapy with dual anti-platelet therapy, the patient presented four weeks later with a spontaneous dissection of the right vertebral artery.ConclusionWe review the presentation, diagnosis, and management of spontaneous dissections of the vasculature in the peri-partum period.