Abstract
Interview with Tanya Stezhka
Tasneem Z Naqvi was affiliated with the University of California, Los Angeles, CA, USA as Associate Professor of Clinical Medicine before joining the Keck School of Medicine at the University of Southern California (CA, USA) in 2007 and the Mayo Clinic in Arizona in 2013. Naqvi is an active member of numerous professional societies including the Vascular Strategy Task Force, the Standards and Guidelines Committee at the American Society of Echocardiography and the American College of Cardiology as a nominee to the Joint Review Committee on Education in Diagnostic Medical Sonography board of directors. Naqvi also served as President of the Los Angeles Society of Echocardiography from 1999 to 2000 and has been a member of the Cardiovascular Imaging Committee and the Education Committee of the American College of Cardiology. She is a member of the Royal College of Physicians in London and a Fellow of the American College of Cardiology and the American Society of Echocardiography.
You currently serve as professor of clinical medicine at the University of Southern California, Echocardiography Services – can you tell us a little bit about your background & how you progressed to your current role?
My journey has been more tedious and complex than that of my peers. In 1987 I left Pakistan to move to England with my 1-year old son and my husband. I spent 4 years practicing and training in medicine in the UK as a registrar. Having completed the Membership of the Royal College of Physicians, my quest for specialty training in cardiology brought me to the USA with my 2-month and 5-year old sons. I started a residency in medicine at Stony Brook Hospital (NY, USA). Two years later, I arrived in Los Angeles to do my clinical cardiology fellowship at Cedars Sinai Medical Center (CA, USA) between 1993 and 1996 and then joined the faculty at that institution. It is interesting how I came to the field of echocardiography; when I finished my cardiology fellowship, I was actually going to do research in basic science. At that time they also needed a helping hand in echocardiography, so a job was created for me that involved 50% research in basic science and 50% in echocardiography. After having spent a year in this split assignment, I remember very distinctly meeting with my mentor and discussing my future time allocation in the two different specialties. I discussed with him how echocardiography and the physiology of the heart and cardiovascular system excited me and from that point on I never looked back, and here I am using echocardiography to study cardiovascular physiology. I was at Cedars Sinai Medical Center up until June 2007 and then I came to the University of Southern California and eventually to the Mayo Clinic to fulfil my desire to establish a state-of-the-art echocardiography laboratory practicing echocardiography to its highest standard and quality, with the most trained and sophisticated sonographers delivering the most professional service, along with active research projects evaluating cardiovascular physiology and setting up core laboratories to be able to bring in cutting-edge multicenter studies at these institutions.
Expert Review of Cardiovascular Therapy turned 10 years of age in May this year. The research field of cardiac pacing has progressed a great deal in this time, can you walk us through the most important trials & findings that you been involved in over the last decade?
I have been involved in several multicenter studies including the ESTEEM trial, the PROSPECT study, the Smart AV delay study and the multipolar LV-LV Pacing study. These were all industry-sponsored multicenter studies that enrolled anywhere from 50 to several hundred patients. In addition, I myself designed several studies in the area of biventricular pacing and I have been actively involved in performing pacemaker optimization as part of clinical patient care for several years. Besides the trials that I have personally been involved with, I think the COMPANION study is what really brought the benefit of biventricular pacing into real context, showing that it not only improves symptoms, but also improves survival. This was then further substantiated by the CARE heart failure study, which also showed the survival benefit of biventricular pacing. I think that these studies have been the highlight of clinical trials, but I must say there have been studies that have also been disappointing; for example, the RethinQ study, which unfortunately reduced and actually killed the enthusiasm for the role of biventricular pacing in patients with narrow QRS, as well as the Prospect study, which diminished the role of mechanical dyssynchrony assessment by echocardiography, at least in a multicenter setting. Prior single-center studies had shown the robust role of mechanical dyssynchrony assessment in predicating response to cardiac resynchronization treatment over and above conventional clinical perimeters. I do believe that mechanical dyssynchrony is real and physiologic and that we need more reproducible echocardiographic markers to assess viability and dyssynchrony.
Are there any people in your institution you feel who practically influence the progression of the field?
Cheuk-Man Yu from Hong Kong has carried out a significant amount of work showing the effect of mechanical dyssynchrony in predicating response to cardiac resynchronization therapy (CRT). Then there is Jeroen Bax from The Netherlands, Peter Sogard from Denmark and John Gorcsan from Pittsburg, who have carried out some very elegant work showing how mechanical dyssynchrony, if performed carefully, can actually determine patients most likely to respond to CRT. There are other names in the field, such as William Abraham, John Sutherland, Serge Cazeau and Michael Gold, who, alongside many other prominant European scientists, have contributed to the field.
What is your view of the current success of cardiac pacing technology? How far how we come & how much room is there for improvement?
Cardiac pacing has come a long way; initially starting from single-chamber pacing to dual-chamber pacing and now to biventricular pacing. There have been developments in the form of multipolar left-ventricular leads, which we have personally evaluated as a core laboratory. It appears promising in that they cause a further reduction in mechanical dyssynchrony over and above biventricular pacing. There is potential left-ventricular endocardial pacing from multiple sites and multipolar right-ventricular lead technology. There is a lot to learn and develop here; for example, we still have not figured out how to improve the responder rate, particularly in the 40% of patients who remain nonresponders despite our best efforts. We still have to figure out how to utilize biventricular pacing in patients with myocardial scarring and in patients who have a limited number of coronary sinus branches for optimal left-ventricular lead placement. Patients with atrial fibrillation and in whom we cannot use the atrioventricular (AV) delay programming – a very important feature of pacemakers – as well as use of biventricular pacing technology in patients who have isolated right-ventricular failure rather than left-ventricular failure. Then there is the problem of fine-tuning multiple AV and interventricular timings within the pacemakers, which, at present, requires a significant amount of time and effort if one is to use echocardiography to guide pacemaker optimization. There is obviously room for noninvasive methods of assessment to help us determine best pacemaker settings for optimal cardiac hemodynamics. Simple, clinically feasible methods that are able to optimize pacemaker settings without requiring significant time and skill are needed. I personally spend an hour and half of my time performing echocardiography-guided optimization. There is no reimbursement for this time at present, which discourages physicians and hospitals from offering these services have been shown in our work to benefit patients.
In your opinion, which recent or current trials are particularly promising for the progression of the field?
There are recently completed trials (REVERSE and RAFT trials) that have shown the utility of cardiac resynchronization in patients with a lower amount of clinical heart failure. I think that these trials will make the use of this technology more vitally available to a wider heart-failure population. There is another EchoCRT trial that is ongoing in over 2000 narrow-QRS patients that may again help us understand the role of mechanical dyssynchrony assessment in determining responses to CRT. Recent news suggests the trial stopped enrollment due to a lack of benefit in the narrow-QRS arm. This narrow-QRS population is intriguing. I personally believe that CRT can offer a benefit to these patients, if we can learn how to select the right patients for CRT.
What do you think will be the most important change to arrhythmic patient care & CRT in the upcoming 10 years?
I think that in the coming 10 years, we will probably see a proliferation of devices that can perform multiple functions at the same time. These include assessment of intracardiac filling pressure, pacemaker function, defibrillator function, ability to pace the heart from multiple sites in multiple chambers and at the same time be able to optimize the timing between different chambers based on patient heart rate and underlying hemodynamic conditions and requirements. There needs to be developments in the pacemaker technology that would allow for beat-to-beat adjustment of AV delay (shortening as well as prolongation) and interventricular delay (shortening as well as prolongation). I personally have the opinion that device therapy should help all patients with heart failure and dilated hearts irrespective of presence of dyssynchrony, myocardial scarring or QRS width. I say this from my personal experience, whereby I have found that manipulating AV delay to improve diastolic filling time during increased heart rates from physical activity is what makes the patients less dyspneic, and this applies to all heart failure patients. I also think there is a role for pacemakers in patients with diastolic heart failure with preserved systolic function by improving diastolic filling time during physical activity.
How far has echocardiography helped & how big of a role will it play in the treatment of arrhythmic patients in the next 10 years?
When it comes to the role of echocardiography in patients who have arrhythmias such as ventricular tachycardia or atrial fibrillation, I am afraid echocardiography has actually not been a big player, at least in the diagnosis or the determination of treatment options for these patients. Obviously we know that patients with significant left atrial enlargement are more prone to atrial fibrillation. We also know that patients with a large ventricular scar or a strategically located scar are prone to ventricular arrhythmias, but as far as echocardiography helping us determine the pathway of arrhythmia propagation, it has not played a significant role. Obviously echocardiography is being used in the catheter laboratory for helping with navigation of the introcardiac catheter to the appropriate sites for ablation, and in particular the use of 3D transesophageal echocardiography has facilitated visualization of anatomy. More recently, the advent of introcadiac echocardiography with 3D capabilities will further enhance the role of echocardiography in visualizing ablation for arrhythmia. Dual ablation and visualization catheters will further improve the localization of substrates to deliver precise ablation.
As well as echocardiography for pacemaker optimization, your focus is also evaluation of carotid intima–media thickness for cardiovascular risk. Could you tell us about this work & where you feel this area is heading?
This is quite a different field compared to pacemaker optimization, so my team is covering a wide spectrum of disease; at one end is pacemaker optimization, which is performed in patients who are extremely sick with heart failure, and at the other end, carotid intima–media thickness (IMT) for cardiovascular risk assessment is typically performed in asymptomatic healthy individuals in whom you are trying to determine the presence of subclinical atherosclerosis and, therefore, the risk of future cardiovascular events. This field has unfortunately lagged in the sense that the technology has been available for over 20 years, used in several pivotal studies to demonstrate the utility of IMT and determining cardiovascular risk and is the most important technology used for development of drugs such as statins and treatment for hypertension and diabetes; however, as far as clinical utility of IMT goes, it is still not a reimbursed test and therefore it is still not being used clinically. The predominant reason behind this is that there is no definitive agreement on the IMT-assessment protocol and varying definitions prevail on what is considered to be a plaque. This has caused a lot of confusion; however, there is recent data emerging that suggests that the assessment of carotid plaques is actually a far better and simpler method of assessing cardiovascular risk. In this regard, there is actually technology that is currently available to perform 3D assessment of carotid plaques, which is currently being evaluated in a multicenter study. The study, led by Valentin Fuster, is going to really help the field determine if indeed this is the best, or at least the better, way of predicting someone’s cardiovascular risk and then to bring that technology into clinical practice. I think that the role of ultrasound in determining cardiovascular and atherosclerotic risk is very important, as it covers a large patient population compared to CRT, which focuses on a relatively small number of inpatients with advanced heart failure.
Disclaimer
The opinions expressed in this interview are those of the interviewee and do not necessarily reflect the views of Expert Reviews Ltd.
Financial & competing interests disclosure
TZ Naqvi is supported by a grant from St Jude Foundation and has previously been supported by grants from Medtronic and Panasonic. The author has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.
No writing assistance was utilized in the production of this manuscript.