Myocardial Injury after Noncardiac Surgery (MINS)

[Pages:137]MYOCARDIAL INJURY AFTER NONCARDIAC SURGERY

M.Sc Thesis ? Fernando O. Botto McMaster University, Health Research Methodology

MYOCARDIAL INJURY AFTER NONCARDIAC SURGERY

By FERNANDO O. BOTTO, M.D.

A Thesis Submitted to the School of Graduate Studies in Partial Fulfilment of the Requirements for the Degree Master of Sciences

McMaster University ? Copyright by Fernando O. Botto, September 2012

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Master of Sciences (2012) Health Research Methodology

M.Sc Thesis ? Fernando O. Botto McMaster University, Health Research Methodology

McMaster University Hamilton, Ontario

TITLE: AUTHOR: SUPERVISOR:

Myocardial Injury after Noncardiac Surgery Fernando O. Botto, MD. Dr Philip J. Devereaux, MD, PhD

NUMBER OF PAGES: xii, 123

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M.Sc Thesis ? Fernando O. Botto McMaster University, Health Research Methodology

ABSTRACT

Worldwide, more than 2 million patients die within 30 days after noncardiac surgery anually. Postoperative ischemic myocardial injury is frequent, however, no consensus exists about its definition. Objective: to develop a term Myocardial Injury after Noncardiac Surgery (MINS) caused by myocardial ischemia, requiring at least, troponin T (TnT) elevation, and with prognostic relevance at 30 days after surgery. Methods: we performed a prospective study including 15,167 patients 45 years-old undergoing noncardiac surgery, who had fourth-generation TnT measurements during the first 3 postoperative days. We undertook Cox regression analyses with 30-day mortality after surgery as the dependent variable, using different TnT thresholds, clinical features and several perioperative variables. Non-ischemic etiologies were excluded. Furthermore, we developed a scoring system to predict risk in MINS patients. Results: MINS was defined as TnT 0.03 ng/mL with or without clinical features, and it was an independent predictor of 30-day mortality (adjusted HR 3.82, CI 95% 2.84-5.10). We determined that MINS incidence was 8%, its population attributable risk 33.7%, and 30days mortality rate 9.6%. Patients did not experience ischemic symptoms in 84% of MINS cases. Additionally, we developed a scoring system in patients suffering MINS with 3 independent predictors of death (age 75 years, new ST elevation or left bundle branch block, and anterior location of ECG changes),

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M.Sc Thesis ? Fernando O. Botto McMaster University, Health Research Methodology

Conclusion: Among patients undergoing noncardiac surgery, we defined MINS based on a TnT threshold 0.03 ng/mL. Mostly, MINS patients were asymptomatic. Therefore, this strongly suggests the importance of a troponin monitoring during the first few days after surgery.

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M.Sc Thesis ? Fernando O. Botto McMaster University, Health Research Methodology

ACKNOWLEDGEMENTS

First of all, I want to express my deepest sense of gratitude to my mentor Dr PJ Devereaux. This thesis would not have been possible without his support, expert advice, unsurpassed knowledge and friendship. I want to thank also for his personal guidance and great effort he put into my research training at the Population Health Research Institute, in Hamilton, Ontario.

I want to thank the other members of my thesis committee, Dr Gordon Guyatt, Dr Lehana Thabane and Dr Daniel Sessler, for their support, insightful comments and also for their grammatical editing of my thesis. I am also thankful to Diane Heels-Ansdell for her outstanding statistical work and advice.

I want to thank to Dr Salim Yusuf who gave me the opportunity to work in the Population Health Research Institute and to Dr Rafael Diaz, Dr Andres Orlandini and Dr Cecilia Bahit from Estudios Clinicos Latino-America (ECLA), Rosario, Argentina, who encouraged me to tackle this challenge. Further, I thank Drs Yusuf, Diaz and Orlandini for their financial help.

I want to thank to Shirley Petit and Andrea Robinson for their continuous technical support, good mood and sweets provision, and to Heather Gill, Dr Devereaux?s assistant, for her kindly support and help during every working day.

I want to thank my parents Nelida and Hector, for their love, encouragement and spiritually support throughout my life, and to my mother and father-in-law, Liliana and Francisco for their love and continuous support during the two years we lived in Canada.

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M.Sc Thesis ? Fernando O. Botto McMaster University, Health Research Methodology

I want to thank also to Mariela and Horacio, and to my sister Karina and Ariel, for being always there, and for their encouragement and help.

Last but not the least, I want to express the love and gratitude from my deep heart to my wife Florencia, and my kids Juana, Francisco and Facundo. Without their support and understanding it would have been impossible for me to accomplish with my Master degree and research fellowship. They all demonstrated integrity, loyalty and an incredible adaptability. I love you!

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M.Sc Thesis ? Fernando O. Botto McMaster University, Health Research Methodology

TABLE OF CONTENTS

Chapter 1. INTRODUCTION................................................................... 1 1.1 The problem..................................................................................... 3 1.2 Thesis proposal.................................................................................. 5 1.3 Thesis objectives................................................................................ 7 1.4 References....................................................................................... 8

Chapter 2. THEORETICAL FRAMEWORK................................................12 2.0 Global burden of noncardiac surgery and relevance of cardiovascular complications........................................................................................12 2.1 Physiopathology of perioperative myocardial ischemia and infarction..................13 2.2 Clinical presentation and prognosis of perioperative myocardial ischemia in noncardiac surgery. Basis for the thesis proposal..............................................20 2.3 Myocardial Injury after Noncardiac surgery. Thesis proposal summary................35 2.4 References.......................................................................................37

Chapter 3. METHODOLOGICAL DESIGN................................................55 3.0 Objectives.........................................................................................55 3.1 Study design......................................................................................55 3.2 Justification for study design...................................................................56 3.3 Elegibility criteria...............................................................................57 3.4 Screening and enrolment of patients.........................................................58 3.5 Variables collected .............................................................................59 3.6 Monitoring, follow-up, and data collection..................................................59 3.7 Statistical and analytical methods.............................................................60 3.8 Participating countries and hospitals.........................................................68 3.9 Study organization..............................................................................68 3.10 Ensuring data quality..........................................................................68

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