Michael J. Mack M.D.

Stone, G. W., J. Lindenfeld, W. T. Abraham, S. Kar, D. S. Lim, J. M. Mishell, B. Whisenant, P. A. Grayburn, M. Rinaldi, S. R. Kapadia, V. Rajagopal, I. J. Sarembock, A. Brieke, S. O. Marx, D. J. Cohen, N. J. Weissman and M. J. Mack (2018). “Transcatheter Mitral-Valve Repair in Patients with Heart Failure.” N Engl J Med 379(24): 2307-2318.

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BACKGROUND: Among patients with heart failure who have mitral regurgitation due to left ventricular dysfunction, the prognosis is poor. Transcatheter mitral-valve repair may improve their clinical outcomes. METHODS: At 78 sites in the United States and Canada, we enrolled patients with heart failure and moderate-to-severe or severe secondary mitral regurgitation who remained symptomatic despite the use of maximal doses of guideline-directed medical therapy. Patients were randomly assigned to transcatheter mitral-valve repair plus medical therapy (device group) or medical therapy alone (control group). The primary effectiveness end point was all hospitalizations for heart failure within 24 months of follow-up. The primary safety end point was freedom from device-related complications at 12 months; the rate for this end point was compared with a prespecified objective performance goal of 88.0%. RESULTS: Of the 614 patients who were enrolled in the trial, 302 were assigned to the device group and 312 to the control group. The annualized rate of all hospitalizations for heart failure within 24 months was 35.8% per patient-year in the device group as compared with 67.9% per patient-year in the control group (hazard ratio, 0.53; 95% confidence interval [CI], 0.40 to 0.70; P<0.001). The rate of freedom from device-related complications at 12 months was 96.6% (lower 95% confidence limit, 94.8%; P<0.001 for comparison with the performance goal). Death from any cause within 24 months occurred in 29.1% of the patients in the device group as compared with 46.1% in the control group (hazard ratio, 0.62; 95% CI, 0.46 to 0.82; P<0.001). CONCLUSIONS: Among patients with heart failure and moderate-to-severe or severe secondary mitral regurgitation who remained symptomatic despite the use of maximal doses of guideline-directed medical therapy, transcatheter mitral-valve repair resulted in a lower rate of hospitalization for heart failure and lower all-cause mortality within 24 months of follow-up than medical therapy alone. The rate of freedom from device-related complications exceeded a prespecified safety threshold. (Funded by Abbott; COAPT ClinicalTrials.gov number, NCT01626079 .).

Thourani, V. H., S. M. O’Brien, J. J. Kelly, D. J. Cohen, E. D. Peterson, M. J. Mack, D. M. Shahian, F. L. Grover, E. J. Carroll, J. M. Brennan, J. Forcillo, S. V. Arnold, S. Vemulapalli, S. Fitzgerald, D. R. Holmes, J. E. Bavaria and F. H. Edwards (2018). “Development and Application of a Risk Prediction Model for In-Hospital Stroke After Transcatheter Aortic Valve Replacement – A Report from the Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy Registry.” Ann Thorac Surg Dec 7. [Epub ahead of print].

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BACKGROUND: Stroke is a serious complication following transcatheter aortic valve replacement (TAVR), yet predictive models are not available. A new risk model for in-hospital stroke following TAVR was developed and used to estimate site-specific performance. METHODS: We included 97,600 TAVR procedures from 521 sites in the STS/ACC Transcatheter Valve Therapy (TVT) Registry from July 2014 through June 2017. Association between baseline covariates and in-hospital stroke was estimated by logistic regression. Discrimination was evaluated by C statistic. Calibration was tested internally via cross validation. Hierarchical modeling was used to estimate risk-adjusted site-specific performance. RESULTS: Median age was 82 years, 44,926 (46.0%) were female, and 1,839 (1.9%) had in-hospital stroke. Covariates associated with stroke (odds ratio) included transapical access (1.44), access excluding transapical and transfemoral (1.77), prior stroke (1.57), prior TIA (1.50), pre-procedural shock, inotropes or mechanical assist device (1.48), smoking (1.28), porcelain aorta (1.23), peripheral arterial disease (1.21), age per 5 years (1.11), glomerular filtration rate per 5 ml/min (0.97), body surface area per m(2) (0.55 male; 0.43 female), and prior aortic valve (0.78) and non-aortic valvular (0.42) procedures. The C statistic was 0.622. Calibration curves demonstrated agreement between observed and expected stroke rates. Hierarchical modeling showed 10 centers (1.9%) with significantly higher odds ratios for in-hospital stroke than their peers. CONCLUSIONS: A risk model for in-hospital stroke following TAVR was developed from the STS/ACC TVT Registry and used to estimate site-specific stroke performance. This model can serve as a valuable resource for quality improvement, clinical decision-making, and patient counseling.

Mack, M., M. Hamandi and A. Gopal (2019). “TAC for TAVR: What Is the Score?” JACC Cardiovasc Imaging 12(1): 133-134.

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Abstract not available.

Mack, M. and M. Hamandi (2019). “Why Surgical Risk Algorithms Are Not Predictive of Transcatheter Aortic Valve Replacement Outcomes!” Circ Cardiovasc Interv 12(1): e007560.

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At least 12 risk algorithms have been constructed in various populations and differing periods to predict outcomes after surgical aortic valve replacement (SAVR). The 2 most widely used are the LES and the STS Predicted Risk of Mortality. The LES was developed in 1995 as an additive score (Additive EuroSCORE) and later converted to a logistic regression model. It was derived from a data set from 8 European countries and was based on a population sample of almost 15,000 patients undergoing all types of cardiac operations. There were 12 covariates identified that were predictive of early mortality in SAVR. The benefit of the LES is its user-friendliness, in that it requires only 18 data fields for the calculation. The shortcoming is that the algorithm is calculated on a relatively small sample size of a diverse set of cardiac operations from nearly 25 years ago. The LES has been repeatedly demonstrated to over-predict actual risk in the assessment of patients for whom surgery poses a high risk in the case of SAVR by a factor of 3. The STS Predicted Risk of Mortality has been more reflective of actual outcomes because it is SAVR specific (versus all cardiac surgical procedures) and based on more current data. An updated risk predictor, EuroSCORE II, was derived from more than 22 000 patients operated on in 2010 in 43 countries worldwide. It includes all cardiac procedures and now has 18 covariates predictive of surgical aortic valve mortality. Whether the accuracy of the EuroSCORE II model has been improved is a subject of debate. A renewed and intense interest has developed in predictive modeling for the management of patients with aortic stenosis because of the introduction of TAVR. When first introduced into clinical practice, TAVR was performed in the highest surgical risk patients. LES and STS Predicted Risk of Mortality were the 2 most common tools used for defining these high surgical risk patients and hence, were widely adopted for TAVR patient selection. However, it should not be surprising that the surgical risk scores have proven to be inaccurate for TAVR because of the fact that the risk algorithms were developed for one procedure and are being applied to a different one. Not only were the risk models neither developed nor validated for TAVR, but they do not take into consideration variables that may play a significant role in risk, including porcelain aorta, previous radiation therapy, liver disease, and frailty since the incidence of those factors were so low in the surgical population in which they were developed and validated. However, these risk scores have used because until now, because they were the best available. In 2016, a TAVR-specific risk model for in-hospital mortality was published. This model was based entirely on TAVR patients included in the STS/American College of Cardiology Transcatheter Valve Registry from 2011 to 2014. It was derived from a patient population of 13,718 and validated on 6,868 different patients in a subsequent time period. It included all commercially available valves in the United States and used 9 variables to predict in-hospital mortality with a C-statistic of 0.66. This is now in the process of being updated to predict 30-day and 1-year mortality after TAVR. (Excerpt from the introduction to, Taratini, G., et al., One-Year Outcomes of a European Transcatheter Aortic Valve Implantation Cohort According to Surgical Risk, Circ Cardiovasc Interv. 2019 Jan;12(1):e006724.)

Blackstone, E. H., H. L. Chang, J. Rajeswaran, M. K. Parides, H. Ishwaran, L. Li, J. Ehrlinger, A. C. Gelijns, A. J. Moskowitz, M. Argenziano, J. J. DeRose, Jr., J. P. Couderc, D. Balda, F. Dagenais, M. J. Mack, G. Ailawadi, P. K. Smith, M. A. Acker, P. T. O’Gara and A. M. Gillinov (2019). “Biatrial maze procedure versus pulmonary vein isolation for atrial fibrillation during mitral valve surgery: New analytical approaches and end points.” J Thorac Cardiovasc Surg 157(1): 234-243.e239.

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OBJECTIVE: To use novel statistical methods for analyzing the effect of lesion set on (long-standing) persistent atrial fibrillation (AF) in the Cardiothoracic Surgical Trials Network trial of surgical ablation during mitral valve surgery (MVS). METHODS: Two hundred sixty such patients were randomized to MVS + surgical ablation or MVS alone. Ablation was randomized between pulmonary vein isolation and biatrial maze. During 12 months postsurgery, 228 patients (88%) submitted 7949 transtelephonic monitoring (TTM) recordings, analyzed for AF, atrial flutter (AFL), or atrial tachycardia (AT). As previously reported, more ablation than MVS-alone patients were free of AF or AF/AFL at 6 and 12 months (63% vs 29%; P < .001) by 72-hour Holter monitoring, without evident difference between lesion sets (for which the trial was underpowered). RESULTS: Estimated freedom from AF/AFL/AT on any transmission trended higher after biatrial maze than pulmonary vein isolation (odds ratio, 2.31; 95% confidence interval, 0.95-5.65; P = .07) 3 to 12 months postsurgery; estimated AF/AFL/AT load (ie, proportion of TTM strips recording AF/AFL/AT) was similar (odds ratio, 0.90; 95% confidence interval, 0.57-1.43; P = .6). Within 12 months, estimated prevalence of AF/AFL/AT by TTM was 58% after MVS alone, and 36% versus 23% after pulmonary vein isolation versus biatrial maze (P < .02). CONCLUSIONS: Statistical modeling using TTM recordings after MVS in patients with (long-standing) persistent AF suggests that a biatrial maze is associated with lower AF/AFL/AT prevalence, but not a lower load, compared with pulmonary vein isolation. The discrepancy between AF/AFL/AT prevalence assessed at 2 time points by Holter monitoring versus weekly TTM suggests the need for a confirmatory trial, reassessment of definitions for failure after ablation, and validation of statistical methods for assessing atrial rhythms longitudinally.