Faculty Bibliography

Although transthoracic echocardiography (TTE) and cardiac magnetic resonance (CMR) are validated in quantitation of mitral regurgitation (MR), discrepancies may occur. This study assesses the agreement between TTE and CMR in MR and evaluates characteristics and clinical outcome of patients with discrepancy. From our institutional database, 70 subjects with MR underwent both TTE and CMR within 30 days (median 3 days). MR was evaluated semiquantitatively (n = 70) using a 4-grade scale and quantitatively (n = 60) with calculation of regurgitant volume (RVol) and regurgitant fraction (RF). Of the 70 subjects, qualitative assessment by TTE yielded 30 subjects with mild MR, 17 moderate, and 23 moderately severe or severe MR. Exact concordance in MR grade was seen in 50% and increased to 91% when considering concordance within one grade of severity (kappa = 0.44). A modest correlation was observed for RVol and RF between both methods (r = 0.59 and 0.54, respectively, p <0.0001). Ten patients had a significant discrepancy in quantitative MR (difference in RF >20%); the frequency of secondary MR was higher (100% vs 46%; p = 0.003) in patients with discrepancy. Although interobserver variability in RF was higher with TTE compared with CMR (-5.5 +/- 15% vs 0.1 +/- 7.3%), patients with discrepancy were equally distributed by severity and clinical outcome without an overestimation by either method. In conclusion, there is a modest agreement between TTE and CMR in assessing MR severity. In patients with discrepancy, there is a higher prevalence of functional MR, without a consistent overestimation of MR severity by either method.

BACKGROUND: Cardiac allograft vasculopathy is a major cause of morbidity and mortality following heart transplantation. Large multicenter studies evaluating the clinical characteristics and inhospital outcomes of heart transplant recipients undergoing percutaneous coronary intervention (PCI) are lacking. OBJECTIVE: To evaluate the clinical characteristics, treatment patterns and inhospital outcomes of heart transplant recipients undergoing PCI compared to general population. METHODS: We analyzed 1,897,328 patients from the National Cardiovascular Data Registry CathPCI registry who underwent PCI of at least 1 native vessel between July 2009 and December 2013 from 1,477 centers, of which 542 patients (0.03%) were heart transplant recipients. Clinical characteristics were evaluated and, after 1:4 propensity matching, inhospital outcomes were compared between 538 heart transplant patients and 2,128 non-transplant patients. RESULTS: Transplant recipients undergoing PCI had a higher prevalence of diabetes, dyslipidemia and peripheral vascular disease; lower prevalence of angina, acute coronary syndrome, abnormal noninvasive functional study, and type C coronary lesions compared to the non-transplant PCI population. After propensity matching, all-cause inhospital mortality was similar between transplant and non-transplant groups (1.3% vs 1.0%; OR, 1.21; 95% CI, 0.54-2.67). CONCLUSION: This is the largest series to date outlining the characteristics of heart transplant recipients undergoing PCI. Similar inhospital outcomes were noted in heart transplant recipients compared to the general population. Further studies evaluating long-term outcomes are warranted.

Dynamic left ventricular outflow tract obstruction and left ventricular mid-cavity obliteration are phenomena that can complicate the postoperative course in patients who undergo surgical aortic valve replacement for aortic stenosis, and may be markers of increased morbidity and mortality. Recently, reports describing dynamic intraventricular obstruction following transcatheter aortic valve replacement (TAVR) have emerged. We report a case of dynamic left ventricular mid-cavity obstruction due to disordered atrioventricular synchrony immediately following TAVR, and its reversal with restoration of atrioventricular synchrony. This case highlights the essential role of atrial contraction in the management of this phenomenon.

Hypertension remains a leading cause of cardiovascular morbidity and mortality worldwide. It is estimated that 12.8% of hypertensive adults have resistant hypertension. The sympathetic nervous system is a well-known contributor to the pathophysiology of resistant hypertension. Renal denervation has emerged as an effective procedure to treat resistant hypertension by blocking the sympathetic nervous system. The medical device industry has developed various catheters in an effort to achieve better denervation in the absence of available testing to document adequate denervation. By adding a sham control group to the study design, researchers found that the results of the Renal Denervation in Patients With Uncontrolled Hypertension study (SYMPLICITY HTN-3) showed that renal denervation was not superior to placebo in decreasing systolic blood pressure. Although SYMPLICITY HTN-3 successfully addressed many issues that might have biased the previously published data, incomplete denervation caused by limited operator experience, catheter design, and the radiofrequency ablation technology may have accounted for the discrepancy of the results. This, along with differences in the study design and population, should direct future renal denervation studies. This article reviews the available literature and proposes future directions for renal denervation studies. It also provides a detailed comparison of the available catheters and their respective clinical data.

BACKGROUND: The objective of this study was to examine the prognostic utility of cardiac magnetic resonance imaging (CMR) in patients with chronic mitral regurgitation undergoing mitral valve repair. METHODS: This study is a prospectively enrolled observational cohort study of 48 consecutive patients with chronic mitral regurgitation who had preoperative evaluation with CMR including delayed-enhancement CMR for assessment of myocardial fibrosis before undergoing mitral valve repair. Postoperative adverse clinical events were defined as intensive care unit readmission, needs of permanent cardiac pacemaker, and rehospitalization for cardiac reasons. RESULTS: The cohort comprised 33 (69%) men with a mean age of 61+/-13 years and mean left ventricular ejection fraction of 0.63+/-0.12. Preoperative myocardial fibrosis was detected in 40% of the patients. Median fibrosis was 4% (interquartile range, 2% to 10%). Mean follow-up duration was 11 months (interquartile range, 1 to 24 months). Adverse clinical events occurred in 16 patients. In multivariate analysis, the presence of myocardial fibrosis was independently associated with postoperative adverse clinical events (hazard ratio, 4.775; 95% confidence interval, 1.100 to 20.729; p=0.037). The addition of the presence of myocardial fibrosis to the preoperative characteristics model significantly improved overall predictive performance (p=0.04). CONCLUSIONS: The presence of preoperative myocardial fibrosis assessed with delayed-enhancement CMR was an independent predictor of increased adverse clinical outcomes in patients with chronic mitral regurgitation undergoing mitral valve repair. Our findings suggest that in this population, preoperative delayed-enhancement CMR may be of clinical utility.

BACKGROUND: Immature platelets are less responsive to the effects of antiplatelet drugs and contain messenger ribonucleic acid that is translationally active. They can be measured easily using an automated hematoanalyzer and reported as part of the complete blood count. OBJECTIVES: The purpose of this study was to determine the prognostic significance of elevated immature platelet count (IPC) in patients with coronary artery disease (CAD). METHODS: In this prospective cohort study in patients with CAD, patients underwent IPC measurement and were then followed up for the composite endpoint of major adverse cardiovascular events (MACE), defined as a composite of all-cause mortality, myocardial infarction, unplanned revascularization, or hospitalization for angina. For the purposes of analysis, patients were stratified into tertiles of IPC. RESULTS: Eighty-nine patients were followed up for a median of 31 months. Stratification to the high IPC tertile was associated with higher rates of MACE compared with the intermediate and low tertiles (60% vs. 24% vs. 16%, respectively; p < 0.001). Time-dependent receiver-operating characteristic analysis revealed that an IPC level >/=7,632 platelets/mul was 70.7% sensitive and 82.1% specific for MACE. After adjustment for age, admission diagnosis, index revascularization, heart failure, smoking, hematocrit, and baseline platelet count, patients with an IPC level >/=7,632 platelets/mul were more likely to experience a MACE (hazard ratio: 4.65; 95% confidence interval: 1.78 to 12.16; p < 0.002). CONCLUSIONS: IPC is a novel biomarker for MACE risk stratification in patients with CAD. Future studies should focus on the utilization of this marker for individualized antiplatelet therapy.

The mechanisms for the variability in antiplatelet effects of clopidogrel are not elucidated entirely. Immature (reticulated) platelets may modulate the antiplatelet effects of clopidogrel but must be measured using flow cytometry. Whether new automated detection techniques yield similar results is not known. The objectives of the study to evaluate the role of immature platelets assessed by an automated method in response to the antiplatelet effects of clopidogrel. Twenty-nine healthy volunteers had platelet studies performed before and 1 week after 75 mg daily dosing of clopidogrel. Immature platelet fraction (IPF) was determined using an automated particle counter. Subjects were stratified into tertiles based on the IPF. Platelet studies included light transmission aggregometry (LTA), and vasodilator stimulated phosphoprotein phosphorylation (VASP-P) determined by platelet reactivity index (PRI). Baseline platelet aggregation responses to 2, 5 and 20 muM ADP, were similar in all three tertiles, however they were greater in the upper than in the lower tertile of immature platelets after clopidogrel in response to 5 muM ADP (54% vs. 23%, P = 0.02), with concordant trends for the other two concentrations. PRI was also greater in the upper tertile after clopidogrel (71.2% vs. 57.8%, P = 0.04). The frequency of clopidogrel hyporesponsiveness (aggregation >50% in response to 5 muM of ADP) was also higher in the upper tertile when compared to lower tertile, (60%) versus (10%) respectively (P = 0.02). [corrected]. Immature platelets measured using an automated method, are associated with impaired response to antiplatelet effects of clopidogrel.