- Email: [email protected]
Controversies in cardiology
Correspondence
Lionel Opie and colleagues (Jan 7, p 69)1 pose the question “In view of the survival benefit shown for coronary-artery bypass grafting, the real controversy is why patients with symptoms and anatomy known to benefit from the procedure are still submitted to percutaneous coronary intervention.” The simple answer is that clinical practice has been distorted by the misunderstanding and inappropriate widespread application of the results of randomised clinical trials, done in highly select populations, to a much wider population.2 There have been 15 randomised trials of percutaneous coronary intervention (PCI) and coronary-artery bypass grafting (CABG) for multivessel coronaryartery disease, which reported a fourfold reduction in the need for repeat intervention with CABG but little difference in survival between the two interventions.2 This apparent lack of survival benefit with CABG was, however, “manufactured” by largely populating the trials with patients with one-vessel or two-vessel coronaryartery disease and normal ventricular function—a population in whom it had already been established that there is little prognostic benefit from surgery.3 This was achieved by excluding around 95% of the screened population from the trials and, in particular, patients known to have prognostic benefit from CABG (those with left mainstem, real triple-vessel disease, severe and complex coronary-artery disease including occluded vessels, and those with impaired ventricular function). Because the patients in the trials were therefore much different from those who actually undergo CABG in the real world, the trials were inherently biased against the survival benefits of CABG. Nevertheless, there is consistently strong evidence of survival advantage with CABG in the real world.4 For example, in the New York Registry of www.thelancet.com Vol 367 April 22, 2006
almost 60 000 risk-matched patients with severe coronary disease, within 3 years of treatment there was an absolute reduction in mortality by around a third and a sevenfold reduction in the need for reintervention in patients undergoing CABG rather than PCI. The survival advantage of CABG is probably because, by contrast with PCI, surgery deals not only with the immediate culprit lesion but also future culprit lesions by placing the graft to the midcoronary vessel, well beyond diseased segments. The current tendency of some cardiologists to abandon the traditional multidisciplinary approach to multivessel coronary-artery disease effectively denies some patients the option of surgery and consequently falls far short of best practice.
modest increases in potassium intake are associated with blood pressure reductions in the order of 4–8 mm Hg systolic and 2–5 mm Hg diastolic in hypertensive individuals.3-5 Furthermore, the antihypertensive effects of increased potassium intake seem to be greatest in those with high dietary salt intake and in blacks.4 Therefore, potassium supplementation, particularly through dietary modification (eg, by increasing intake of fruits and vegetables) is a cheap, easy, effective, and safe means to reduce blood pressure in hypertensive patients with preserved renal function. I declare that I have no conflict of interest.
Steven G Coca [email protected] Yale University School of Medicine, New Haven, CT 06520, USA 1
I declare that I have no conflict of interest.
David P Taggart
2
[email protected] Department of Cardiac Surgery, Oxford Heart Centre, John Radcliffe Hospital, Oxford OX3 9DU, UK 1
2
3
4
Opie LH, Commerford PJ, Gersh BJ. Controversies in cardiology 1: controversies in stable coronary artery disease. Lancet 2006; 367: 69–78. Taggart DP. Surgery is the best intervention for severe coronary artery disease. BMJ 2005; 330: 785–86. Yusuf S, Zucker D, Peduzzi P, et al. Effect of coronary artery bypass graft surgery on survival: overview of 10-year results from randomised trials by the Coronary Artery Bypass Graft Surgery Trialists Collaboration. Lancet 1994; 344: 563–70. Hannan EL, Racz MJ, Walford G, et al. Longterm outcomes of coronary-artery bypass grafting versus stent implantation. N Engl J Med 2005; 352: 2174–83.
The article on controversies in hypertension by Norman Kaplan and Lionel Opie (Jan 14, p 168)1 was thorough and insightful. However, Kaplan and Opie did not mention one key, additional strategy for blood pressure reduction—ie, an increase in potassium intake. Potassium intake is inadequate in a large proportion of the general population and is generally the lowest in blacks.2 Several clinical trials and three meta-analyses have shown that
e-mail submissions to [email protected]
3
4
5
Kaplan NM, Opie LH. Controversies in cardiology 2: controversies in hypertension. Lancet 2006; 367: 168–76. Institute of Medicine. Dietary reference intakes: water, potassium, sodium chloride, and sulfate, 1st edn. Washington, DC: National Academy Press, 2004. Cappuccio FP, MacGregor GA. Does potassium supplementation lower blood pressure? A meta-analysis of published trials. J Hypertens 1991; 9: 465–73. Whelton PK, He J, Cutler JA, et al. Effects of oral potassium on blood pressure: metaanalysis of randomized controlled clinical trials. JAMA 1997; 277: 1624–32. Geleijnse JM, Kok FJ, Grobbee DE. Blood pressure response to changes in sodium and potassium intake: a metaregression analysis of randomised trials. J Hum Hypertens 2003; 17: 471–80.
Norman Kaplan and Lionel Opie’s article on hypertension1 is timely, but its halfhearted approach to this pandemic is most disappointing. They rightly point out the importance of lowering population blood pressure by public health approaches, but then pour cold water on diet and lifestyle changes, casting doubt that, in populations, such measures can be applied. They ignore the fact that, in most developed countries, much of the salt, saturated fat, and sugar in the diet is hidden in processed foods, meaning that the changes required to lower blood pressure are largely in the hands of the food industry and
Rights were not granted to include this image in electronic media. Please refer to the printed journal.
1313
Science Photo Library
Controversies in cardiology
Lionel Opie and colleagues (Jan 7, p 69)1 pose the question “In view of the survival benefit shown for coronary-artery bypass grafting, the real controversy is why patients with symptoms and anatomy known to benefit from the procedure are still submitted to percutaneous coronary intervention.” The simple answer is that clinical practice has been distorted by the misunderstanding and inappropriate widespread application of the results of randomised clinical trials, done in highly select populations, to a much wider population.2 There have been 15 randomised trials of percutaneous coronary intervention (PCI) and coronary-artery bypass grafting (CABG) for multivessel coronaryartery disease, which reported a fourfold reduction in the need for repeat intervention with CABG but little difference in survival between the two interventions.2 This apparent lack of survival benefit with CABG was, however, “manufactured” by largely populating the trials with patients with one-vessel or two-vessel coronaryartery disease and normal ventricular function—a population in whom it had already been established that there is little prognostic benefit from surgery.3 This was achieved by excluding around 95% of the screened population from the trials and, in particular, patients known to have prognostic benefit from CABG (those with left mainstem, real triple-vessel disease, severe and complex coronary-artery disease including occluded vessels, and those with impaired ventricular function). Because the patients in the trials were therefore much different from those who actually undergo CABG in the real world, the trials were inherently biased against the survival benefits of CABG. Nevertheless, there is consistently strong evidence of survival advantage with CABG in the real world.4 For example, in the New York Registry of www.thelancet.com Vol 367 April 22, 2006
almost 60 000 risk-matched patients with severe coronary disease, within 3 years of treatment there was an absolute reduction in mortality by around a third and a sevenfold reduction in the need for reintervention in patients undergoing CABG rather than PCI. The survival advantage of CABG is probably because, by contrast with PCI, surgery deals not only with the immediate culprit lesion but also future culprit lesions by placing the graft to the midcoronary vessel, well beyond diseased segments. The current tendency of some cardiologists to abandon the traditional multidisciplinary approach to multivessel coronary-artery disease effectively denies some patients the option of surgery and consequently falls far short of best practice.
modest increases in potassium intake are associated with blood pressure reductions in the order of 4–8 mm Hg systolic and 2–5 mm Hg diastolic in hypertensive individuals.3-5 Furthermore, the antihypertensive effects of increased potassium intake seem to be greatest in those with high dietary salt intake and in blacks.4 Therefore, potassium supplementation, particularly through dietary modification (eg, by increasing intake of fruits and vegetables) is a cheap, easy, effective, and safe means to reduce blood pressure in hypertensive patients with preserved renal function. I declare that I have no conflict of interest.
Steven G Coca [email protected] Yale University School of Medicine, New Haven, CT 06520, USA 1
I declare that I have no conflict of interest.
David P Taggart
2
[email protected] Department of Cardiac Surgery, Oxford Heart Centre, John Radcliffe Hospital, Oxford OX3 9DU, UK 1
2
3
4
Opie LH, Commerford PJ, Gersh BJ. Controversies in cardiology 1: controversies in stable coronary artery disease. Lancet 2006; 367: 69–78. Taggart DP. Surgery is the best intervention for severe coronary artery disease. BMJ 2005; 330: 785–86. Yusuf S, Zucker D, Peduzzi P, et al. Effect of coronary artery bypass graft surgery on survival: overview of 10-year results from randomised trials by the Coronary Artery Bypass Graft Surgery Trialists Collaboration. Lancet 1994; 344: 563–70. Hannan EL, Racz MJ, Walford G, et al. Longterm outcomes of coronary-artery bypass grafting versus stent implantation. N Engl J Med 2005; 352: 2174–83.
The article on controversies in hypertension by Norman Kaplan and Lionel Opie (Jan 14, p 168)1 was thorough and insightful. However, Kaplan and Opie did not mention one key, additional strategy for blood pressure reduction—ie, an increase in potassium intake. Potassium intake is inadequate in a large proportion of the general population and is generally the lowest in blacks.2 Several clinical trials and three meta-analyses have shown that
e-mail submissions to [email protected]
3
4
5
Kaplan NM, Opie LH. Controversies in cardiology 2: controversies in hypertension. Lancet 2006; 367: 168–76. Institute of Medicine. Dietary reference intakes: water, potassium, sodium chloride, and sulfate, 1st edn. Washington, DC: National Academy Press, 2004. Cappuccio FP, MacGregor GA. Does potassium supplementation lower blood pressure? A meta-analysis of published trials. J Hypertens 1991; 9: 465–73. Whelton PK, He J, Cutler JA, et al. Effects of oral potassium on blood pressure: metaanalysis of randomized controlled clinical trials. JAMA 1997; 277: 1624–32. Geleijnse JM, Kok FJ, Grobbee DE. Blood pressure response to changes in sodium and potassium intake: a metaregression analysis of randomised trials. J Hum Hypertens 2003; 17: 471–80.
Norman Kaplan and Lionel Opie’s article on hypertension1 is timely, but its halfhearted approach to this pandemic is most disappointing. They rightly point out the importance of lowering population blood pressure by public health approaches, but then pour cold water on diet and lifestyle changes, casting doubt that, in populations, such measures can be applied. They ignore the fact that, in most developed countries, much of the salt, saturated fat, and sugar in the diet is hidden in processed foods, meaning that the changes required to lower blood pressure are largely in the hands of the food industry and
Rights were not granted to include this image in electronic media. Please refer to the printed journal.
1313
Science Photo Library
Controversies in cardiology