Michael J. Mack M.D.

Carroll, J. D., S. Vemulapalli, D. Dai, R. Matsouaka, E. Blackstone, F. Edwards, F. A. Masoudi, M. Mack, E. D. Peterson, D. Holmes, J. S. Rumsfeld, E. M. Tuzcu and F. Grover (2017). “Procedural experience for transcatheter aortic valve replacement and relation to outcomes: The sts/acc tvt registry.” J Am Coll Cardiol 70(1): 29-41.

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BACKGROUND: Transcatheter aortic valve replacement (TAVR) has been introduced into U.S. clinical practice with efforts to optimize outcomes and minimize the learning curve. OBJECTIVES: The goal of this study was to assess the degree to which increasing experience during the introduction of this procedure, separated from other outcome determinants including patient and procedural characteristics, is associated with outcomes. METHODS: The authors evaluated the association of hospital TAVR volume and patient outcomes for TAVR by using data from 42,988 commercial procedures conducted at 395 hospitals submitting to the Transcatheter Valve Therapy Registry from 2011 through 2015. Outcomes assessed included adjusted and unadjusted in-hospital major adverse events. RESULTS: Increasing site volume was associated with lower in-hospital risk-adjusted outcomes, including mortality (p < 0.02), vascular complications (p < 0.003), and bleeding (p < 0.001) but was not associated with stroke (p = 0.14). From the first case to the 400th case in the volume-outcome model, risk-adjusted adverse outcomes declined, including mortality (3.57% to 2.15%), bleeding (9.56% to 5.08%), vascular complications (6.11% to 4.20%), and stroke (2.03% to 1.66%). Vascular and bleeding volume-outcome associations were nonlinear with a higher risk of adverse outcomes in the first 100 cases. An association of procedure volume with risk-adjusted outcomes was also seen in the subgroup having transfemoral access. CONCLUSIONS: The initial adoption of TAVR into practice in the United States showed that increasing experience was associated with better outcomes. This association, whether deemed a prolonged learning curve or a manifestation of a volume-outcome relationship, suggested that concentrating experience in higher volume heart valve centers might be a means of improving outcomes.

Yahagi, K., E. Ladich, R. Kutys, H. Mori, L. G. Svensson, M. J. Mack, H. C. Herrmann, C. R. Smith, M. B. Leon, R. Virmani and A. V. Finn (2017). “Pathology of balloon-expandable transcatheter aortic valves.” Catheter Cardiovasc Interv: 2017 Jun [Epub ahead of print].

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BACKGROUND: The Placement of AoRtic TraNscathetER Valves trials (PARTNER) showed favorable safety and efficacy versus medical or surgical therapy in inoperable, high, and intermediate surgical risk patients with severe aortic stenosis. However, the biological responses to transcatheter aortic valves have not been well characterized. OBJECTIVES: The aim of this study was to perform pathologic assessment of Edwards SAPIEN transcatheter aortic valves removed either at autopsy or surgically during the PARTNER I and II clinical trials. METHODS: Explanted valves and frame were evaluated for pathologic responses including extent of thrombus, inflammation, neointima, and leaflet degeneration/calcification according to semiquantitative grading by implant duration (90 days). RESULTS: A total of 22 cases (median age 82.0 years, 45% men) were included, with a duration of implantation that ranged from 0 to 1739 days (median duration 16.5 days [interquartile range, 2.8-68.3]). Valve thrombosis resulting in severe aortic stenosis was observed in one case. Moderate leaflet thrombus was seen in 14% of cases (n = 3) and all were asymptomatic. Calcification was seen in two valves: one with severe leaflet calcification had severe aortic stenosis requiring surgical replacement, while the other showed early calcification. Mild structural leaflet changes were exclusively seen in valve implants >90 days. Valve inflammation and thrombus formation was mild in majority of the cases. CONCLUSIONS: Overall, our study demonstrates moderate thrombus formation in 14% and calcification in only 2 valves, >/=4 years duration. In this short-duration study, acceptable durability and biocompatibility of the Edwards SAPIEN transcatheter valve system was demonstrated; however, further studies are required to confirm the significance and application of our findings.

Mumtaz, M., H. Gada, M. J. Mack and M. J. Reardon (2017). “Who’s afraid of the big bad wolf?” J Thorac Cardiovasc Surg 153(6): 1287-1289.

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Surgical aortic valve replacement (SAVR) for the treatment of symptomatic severe aortic stenosis is arguably one of the most successful cardiac procedures ever developed. Since the introduction of SAVR in 1960, millions of lives have been saved and improved. Although never tested against the previous standard of care, medical therapy, we as surgeons knew it was the right choice because without SAVR these patients were resigned to heart failure and death. We did track our outcomes both individually and nationally by the creation of the Society of Thoracic Surgery Adult Cardiac Surgery database, which now encompasses more than 6.1 million patients contributed by more than 95% of cardiac surgeons in the United States.

Milojevic, M., S. J. Head, M. J. Mack, F. W. Mohr, M. C. Morice, K. D. Dawkins, D. R. Holmes, Jr., P. W. Serruys and A. P. Kappetein (2017). “Influence of practice patterns on outcome among countries enrolled in the syntax trial: 5-year results between percutaneous coronary intervention and coronary artery bypass graftingdagger.” Eur J Cardiothorac Surg: 2017 May [Epub ahead of print].

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OBJECTIVES: To examine differences among participating countries in baseline characteristics, clinical practice, medication strategies and outcomes of patients randomized to coronary artery bypass grafting and percutaneous coronary intervention in the SYNTAX trial. METHODS: In SYNTAX, centres in 18 different countries enrolled 1800 patients, of which 8 countries enrolled >/=80 patients, what was projected to be a large enough sample size to be included in the analysis. Baseline characteristics, practice patterns and clinical outcomes were compared between the USA ( n = 245), the UK ( n = 267), Italy ( n = 197), France ( n = 208), Germany ( n = 179), Netherlands ( n = 148), Belgium ( n = 91) and Hungary ( n = 83). The remaining patients from other participating countries were pooled together ( n = 382). RESULTS: Five-year results demonstrated significantly different outcomes between countries. After adjustment, percutaneous coronary intervention patients in France had lower rates of major adverse cardiac and cerebrovascular events [hazard ratio (HR) = 0.60, 95% confidence interval (CI) 0.37-0.98], while the incidence of repeat revascularization was higher in Hungary (HR = 1.89, 95% CI 1.14-3.42). Coronary artery bypass grafting showed the lowest rate of repeat revascularization in the UK (HR = 0.32, 95% CI 0.12-0.85). There were numerous differences in the risk profile of patients between participating countries, as well as marked differences in surgical practice across countries in the use of blood cardioplegia (range 3.1-89.0%; P < 0.001), bilateral internal mammary artery usage (range 7.8-68.2%; P < 0.001) and off-pump procedures (range 3.9-44.4%; P < 0.001). Variation was also found for percutaneous coronary intervention in the number of implanted stents (range 4.0 +/- 2.3 to 6.1 +/- 2.6; P < 0.001) as well as for the entire stents length (range 69.0 +/- 45.1 to 124.1 +/- 60.9; P < 0.001). Remarkable differences were observed in the prescription of post-coronary artery bypass grafting medication in terms of acetylsalicylic acid (range 79.6-95.0%; P = 0.004), thienopyridine (6.8-31.1%; P < 0.001) and statins (41.3-89.1%; P < 0.001). CONCLUSIONS: Patient characteristics and clinical patterns are significantly different between countries, resulting in significantly different 5-year outcomes. This article presents specific data that can further improve outcomes in each country.

Webb, J. G., M. J. Mack, J. M. White, D. Dvir, P. Blanke, H. C. Herrmann, J. Leipsic, S. K. Kodali, R. Makkar, D. C. Miller, P. Pibarot, A. Pichard, L. F. Satler, L. Svensson, M. C. Alu, R. M. Suri and M. B. Leon (2017). “Transcatheter aortic valve implantation within degenerated aortic surgical bioprostheses: Partner 2 valve-in-valve registry.” J Am Coll Cardiol 69(18): 2253-2262.

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BACKGROUND: Early experience with transcatheter aortic valve replacement (TAVR) within failed bioprosthetic surgical aortic valves has shown that valve-in-valve (VIV) TAVR is a feasible therapeutic option with acceptable acute procedural results. OBJECTIVES: The authors examined 30-day and 1-year outcomes in a large cohort of high-risk patients undergoing VIV TAVR. METHODS: Patients with symptomatic degeneration of surgical aortic bioprostheses at high risk (>/=50% major morbidity or mortality) for reoperative surgery were prospectively enrolled in the multicenter PARTNER (Placement of Aortic Transcatheter Valves) 2 VIV trial and continued access registries. RESULTS: Valve-in-valve procedures were performed in 365 patients (96 initial registry, 269 continued access patients). Mean age was 78.9 +/- 10.2 years, and mean Society of Thoracic Surgeons score was 9.1 +/- 4.7%. At 30 days, all-cause mortality was 2.7%, stroke was 2.7%, major vascular complication was 4.1%, conversion to surgery was 0.6%, coronary occlusion was 0.8%, and new pacemaker insertion was 1.9%. One-year all-cause mortality was 12.4%. Mortality fell from the initial registry to the subsequent continued access registry, both at 30 days (8.2% vs. 0.7%, respectively; p = 0.0001) and at 1 year (19.7% vs. 9.8%, respectively; p = 0.006). At 1 year, mean gradient was 17.6 mm Hg, and effective orifice area was 1.16 cm2, with greater than mild paravalvular regurgitation of 1.9%. Left ventricular ejection fraction increased (50.6% to 54.2%), and mass index decreased (135.7 to 117.6 g/m2), with reductions in both mitral (34.9% vs. 12.7%) and tricuspid (31.8% vs. 21.2%) moderate or severe regurgitation (all p < 0.0001). Kansas City Cardiomyopathy Questionnaire score increased (mean: 43.1 to 77.0) and 6-min walk test distance results increased (mean: 163.6 to 252.3 m; both p < 0.0001). CONCLUSIONS: In high-risk patients, TAVR for bioprosthetic aortic valve failure is associated with relatively low mortality and complication rates, improved hemodynamics, and excellent functional and quality-of-life outcomes at 1 year.