European Heart Journal Advance Access originally published online on May 4, 2005
European Heart Journal 2005 26(14):1448; doi:10.1093/eurheartj/ehi318
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Enhancement of perfusion reserve by cardiac resynchronization therapy: reply
Institute of Molecular Biophysics, Radiopharmacy, and Nuclear Medicine
Heart and Diabetes Center North Rhine-Westphalia
Bad Oeynhausen, Germany
Tel: +49 5731 97 1309
Fax: +49 5731 97 2190
E-mail address: olindner{at}hdz-nrw.de
Department of Cardiology
Heart and Diabetes Center North Rhine-Westphalia
Bad Oeynhausen, Germany
Institute of Molecular Biophysics, and Radiopharmacy, and Nuclear Medicine
Heart and Diabetes Center North Rhine-Westphalia
Bad Oeynhausen, Germany
The letter from Dr Knaapen and co-workers raised an interesting and critical point about our conclusion that further studies have to clarify whether long-term cardiac resynchronization therapy (CRT) is able to improve myocardial perfusion and metabolism at a global level, suggesting a regression of cardiomyopathy. This conclusion was based on the observation that global resting MBF and MVO2, which were reduced in our cardiomyopathy patients, did not change after 4 months of CRT.1 As recently demonstrated, there is evidence that CRT is able to improve hyperaemic MBF (1.91±1.03 at baseline vs. 2.66±1.66 after 3 months of CRT vs. 1.92±1.06 mL/min/g during CRT off), which may play a role in functional recovery by CRT due to a reduction in ischaemic episodes.2 However, this observation was not confirmed by the study of Sundell et al.,3 who reported no significant change in vasodilator MBF (1.8±1.1 during CRT on vs. 1.6±0.9 mL/min/g during CRT off) after 8±5 months of CRT.
The point of discussion now is to define which criteria need to be applied before one can talk about a real regression of cardiomyopathy. It is beyond doubt that the benefit of CRT is related to an electromechanical resynchronization of the left ventricle, which induces, among other things, a reverse remodelling process and potential improvements in hyperaemic MBF. But as Knaapen et al.2 also demonstrated, the effect on hyperaemic MBF vanishes as soon as CRT is interrupted. Therefore, we regard it as justified to state that the underlying cardiomyopathic process is not essentially suspended by CRT within a 3–4-month observation period. Nevertheless, the results of Knaapen et al.2 indicate that CRT initiates mechanisms which could induce a real regression of cardiomyopathy over a long-term period.
Within this context, there is, in our opinion, a basic need to clarify the range of quantitative MBF and MVO2 in advanced cardiomyopathy. As the current scientific literature indicates, there exists a wide range of data, based to some extent on different methodological approaches, to measure MBF and MVO2.
References
- Lindner O, Vogt J, Kammeier A, Wielepp P, Holzinger J, Baller D, Lamp B, Hansky B, Korfer R, Horstkotte D, Burchert W. Effect of cardiac resynchronization therapy on global and regional oxygen consumption and myocardial blood flow in patients with non-ischaemic and ischaemic cardiomyopathy. Eur Heart J 2005; 26:70–76.
[Abstract/Free Full Text] - Knaapen P, van Campen LM, de Cock CC, Gotte MJ, Visser CA, Lammertsma AA, Visser FC. Effects of cardiac resynchronization therapy on myocardial perfusion reserve. Circulation 2004;110:646–651.
[Abstract/Free Full Text] - Sundell J, Engblom E, Koistinen J, Ylitalo A, Naum A, Stolen KQ, Kalliokoski R, Nekolla SG, Airaksinen KE, Bax JJ, Knuuti J. The effects of cardiac resynchronization therapy on left ventricular function, myocardial energetics, and metabolic reserve in patients with dilated cardiomyopathy and heart failure. J Am Coll Cardiol 2004;43:1027–1033.
[Abstract/Free Full Text]
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