Cardiology

Packer, M. (2016). “Cobalt cardiomyopathy: A critical reappraisal in light of a recent resurgence.” Circ Heart Fail 9(12).

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Cobalt can cause a distinctive, rapidly progressive and reversible depression of cardiac systolic function, which is readily distinguished from other causes of cardiomyopathy. Patients present with the subacute onset of severe heart failure, which is accompanied by hypotension and cyanosis, pericardial effusion, low voltage on the electrocardiogram, marked elevation of serum enzymes, and lactic acidosis. They typically have a history of lethargy, anorexia, and weight loss in the months preceding the illness and exhibit other evidence of cobalt’s effects on the body (eg, polycythemia and goiter). The course of cobalt-related cardiomyopathy may be progressive and fatal, but those who survive and cease exposure generally demonstrate complete resolution of symptoms and recovery of cardiac function. Patients presenting with rapid onset of cardiomyopathy, who also exhibit polycythemia, pericardial effusion, or goiter should be evaluated for cobalt exposure. Exposure can be confirmed by the measurement of cobalt in the serum, but serum levels of the ion are not reliably predictive of clinical cardiotoxicity. The clinical emergence of cobalt cardiomyopathy seems to require the coexistence of one or more cofactors, particularly a low-protein diet, thiamine deficiency, alcoholism, and hypothyroidism. As the medicinal use of cobalt has waned and measures to reduce industrial exposure have been implemented, subacute cobalt-related cardiomyopathy had become rare. However, reports describing classical features of the disease have recently surged among patients with a malfunctioning cobalt-alloy hip prosthesis.

Desai, A. S., O. Vardeny, B. Claggett, J. J. McMurray, M. Packer, K. Swedberg, J. L. Rouleau, M. R. Zile, M. Lefkowitz, V. Shi and S. D. Solomon (2016). “Reduced risk of hyperkalemia during treatment of heart failure with mineralocorticoid receptor antagonists by use of sacubitril/valsartan compared with enalapril: A secondary analysis of the paradigm-hf trial.” JAMA Cardiol: 2016 Nov [Epub ahead of print].

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Importance: Consensus guidelines recommend the use of mineralocorticoid receptor antagonists (MRAs) for selected patients with symptomatic heart failure and reduced ejection fraction (HFrEF) to reduce morbidity and mortality; however, the use of MRAs in combination with other inhibitors of the renin-angiotensin-aldosterone system increases the risk of hyperkalemia. Objective: To determine whether the risk of hyperkalemia associated with use of MRAs for patients with HFrEF is reduced by sacubitril/valsartan in comparison with enalapril. Design, Setting, and Participants: The PARADIGM-HF (Prospective Comparison of ARNI With an ACE-Inhibitor to Determine Impact on Global Mortality and Morbidity in Heart Failure) trial randomly assigned 8399 patients with chronic HF, New York Heart Association class II to IV symptoms, and a left ventricular EF of 40% or less to treatment with enalapril 10 mg twice daily or sacubitril/valsartan 97/103 mg twice daily (previously known as LCZ696 [200 mg twice daily]) in addition to guideline-directed medical therapy. Use of MRAs was encouraged but left to the discretion of study investigators. Serum potassium level was measured at every study visit. The incidence of hyperkalemia (potassium level >5.5 mEq/L) and severe hyperkalemia (potassium level >6.0 mEq/L) among patients treated or not treated with an MRA at baseline and the risk of subsequent hyperkalemia for those newly treated with an MRA during study follow-up were defined in time-updated Cox proportional hazards models. Analyses were conducted between August 1 and October 15, 2016. Main Outcomes and Measures: Incident hyperkalemia and severe hyperkalemia. Results: In comparison with the 3728 patients (44.4% of enrolled participants [21.6% female]) not taking an MRA at baseline, the 4671 patients (55.6% [22.0% female]) taking an MRA tended to be younger, with a lower EF, lower systolic blood pressure, and more advanced HF symptoms. Among those taking an MRA at baseline, the overall rates of hyperkalemia were similar between treatment groups, but severe hyperkalemia was more common in patients randomly assigned to enalapril than to sacubitril/valsartan (3.1 vs 2.2 per 100 patient-years; HR, 1.37 [95% CI, 1.06-1.76]; P = .02). In analyses including patients who newly started taking MRAs during the PARADIGM-HF trial, severe hyperkalemia remained more common in those randomly assigned to enalapril than to those randomly assigned to sacubitril/valsartan (3.3 vs 2.3 per 100 patient-years; HR, 1.43 [95% CI, 1.13-1.81]; P = .003). Conclusions and Relevance: Among MRA-treated patients with symptomatic HFrEF, severe hyperkalemia is more likely during treatment with enalapril than with sacubitril/valsartan. These data suggest that neprilysin inhibition attenuates the risk of hyperkalemia when MRAs are combined with other inhibitors of the renin-angiotensin-aldosterone system in patients with HF.

Squiers, J. J., K. R. Hebeler, J. M. DiMaio, P. Ogbue, M. Szerlip and W. T. Brinkman (2016). “Impingement of single-tilting disc mitral prosthesis during transcatheter aortic valve replacement.” Ann Thorac Surg 102(6): e529-e531.

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An 80-year-old woman with a medical history of mitral valve replacement with single-tilting disc prosthesis underwent transcatheter aortic valve replacement (TAVR). The tilting disc was noted to have abnormal motion after re-ballooning of the TAVR valve. Cardiopulmonary bypass was initiated, and the procedure was converted to surgical aortic valve replacement. After removal of the TAVR valve, the tilting disc moved freely. Although TAVR in patients with mitral prostheses is technically feasible, particular caution is necessary, and postdeployment dilation should be avoided.

Capoulade, R., X. Zeng, J. R. Overbey, G. Ailawadi, J. H. Alexander, D. Ascheim, M. Bowdish, A. C. Gelijns, P. Grayburn, I. L. Kron, R. A. Levine, M. J. Mack, S. Melnitchouk, R. E. Michler, J. C. Mullen, P. O’Gara, M. K. Parides, P. Smith, P. Voisine and J. Hung (2016). “Impact of left ventricular to mitral valve ring mismatch on recurrent ischemic mitral regurgitation after ring annuloplasty.” Circulation 134(17): 1247-1256.

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BACKGROUND: In ischemic mitral regurgitation (IMR), ring annuloplasty is associated with a significant rate of recurrent MR. Ring size is based on intertrigonal distance without consideration of left ventricular (LV) size. However, LV size is an important determinant of mitral valve (MV) leaflet tethering before and after repair. We aimed to determine whether LV-MV ring mismatch (mismatch of LV size relative to ring size) is associated with recurrent MR in patients with IMR after restrictive ring annuloplasty. METHODS: Patients with moderate or severe IMR from the 2 Cardiothoracic Surgical Trials Network IMR trials who received MV repair were examined at 1 year after surgery. Baseline LV size was assessed by LV end-diastolic dimension and LV end-systolic dimension (LVESd). LV-MV ring mismatch was calculated as the ratio of LV to ring size (LV end-diastolic dimension/ring size and LVESd/ring size). RESULTS: At 1 year after ring annuloplasty, 45 of 214 patients with MV repair (21%) had moderate or greater MR. In univariable logistic regression analysis, larger LVESd (P=0.02) and LVESd/ring size (P=0.007) were associated with recurrent MR. In multivariable models adjusted for age, sex, baseline LV ejection fraction, and severe IMR, only LVESd/ring size (odd ratio per 0.5 increase, 2.20; 95% confidence interval, 1.05-4.62; P=0.038) remained significantly associated with 1-year MR recurrence. CONCLUSIONS: LV-MV ring size mismatch is associated with increased risk of MR recurrence. This finding may be helpful in guiding choice of ring size to prevent recurrent MR in patients undergoing MV repair and in identifying patients who may benefit from MV repair with additional subvalvular intervention or MV replacement rather than repair alone.

Kurlansky, P., M. Herbert, S. Prince and M. Mack (2016). “Coronary artery bypass graft versus percutaneous coronary intervention: Meds matter: Impact of adherence to medical therapy on comparative outcomes.” Circulation 134(17): 1238-1246.

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BACKGROUND: Multiple studies have compared coronary artery bypass graft (CABG) with percutaneous coronary interventions (PCI) for coronary revascularization. There is considerable evidence that adherence to medical therapy can affect the outcomes of therapeutic interventions. However, the long-term influence of compliance with recommended medical therapy on the comparative outcomes of CABG versus PCI remains to be defined. METHODS: All non-ST-segment-elevation myocardial infarction patients undergoing coronary revascularization in an 8-hospital network were followed for up to 8 years to determine medication history and major adverse cardiac events: all-cause mortality, nonfatal myocardial infarction, and reintervention. All mortalities were checked against the Social Security Death Index. Survival curves were derived with Kaplan-Meier methods; hazard ratios were calculated with the Cox proportional hazard model; and propensity score matching was used to account for differences in patient selection. RESULTS: Among the 973 CABG and 2255 PCI patients, Kaplan-Meier major adverse cardiac event-free survival curves demonstrated a significant benefit for antiplatelet, lipid-lowering, and beta-blocker therapy in both the CABG and PCI groups (P=0.001 for all 3 medications). Cox regression identified compliance with optimal medical therapy as a more powerful predictor of major adverse cardiac event-free survival than choice of therapy (hazard ratio for noncompliance=2.79; 95% confidence limits, 2.19-3.54; P<0.001; hazard ratio for PCI versus CABG=1.68, 95% confidence limits, 138-2.04; P<0.001). In propensity-matched patients, CABG outcomes were superior to PCI outcomes in patients nonadherent to optimal medical therapy (P=0.001) but were not different in patients adherent to optimal medical therapy (P=0.574). CONCLUSIONS: Regardless of coronary revascularization strategy, medication adherence has a dramatic effect on long-term outcome. Among comparable patients who adhere to optimal medical therapy, outcomes of PCI and CABG may not differ; however, among nonadherent patients, CABG affords better major adverse cardiac event-free survival. Therefore, patient compliance with medical therapy may inform clinical decision making and should be incorporated into all future comparative studies of comparative coronary revascularization strategies.