Open Access Study protocol

Rationale and design of the myocardial microinjury and cardiac remodeling extension study in the sodium lowering in dialysate trial (Mac-SoLID study)

Joanna Leigh Dunlop12, Alain Charles Vandal34, Janak Rashme de Zoysa15, Ruvin Sampath Gabriel6, Lukas Mathias Gerber5, Imad Adbi Haloob7, Christopher John Hood12, John Hamilton Irvine8, Philip James Matheson9, David Owen Ross McGregor8, Kannaiyan Samuel Rabindranath10, John Benedict William Schollum11, David John Semple7 and Mark Roger Marshall1122*

Author Affiliations

1 Faculty of Medical and Health Sciences, University of Auckland, Private Bag 93311, Otahuhu, Auckland 1640, New Zealand

2 Department of Renal Medicine, Middlemore Hospital, Counties Manukau District Health Board, Private Bag 93311, Otahuhu, Auckland 1640, New Zealand

3 Faculty of Health and Environmental Sciences, Auckland University of Technology, North Shore Campus, Private Bag 92006, Auckland 1142, New Zealand

4 Ko Awatea, Middlemore Hopsital, Counties Manukau District Health Board, Private Bag 93311, Otahuhu, Auckland 1640, New Zealand

5 Renal Service, North Shore Hospital, Waitemata District Health Board, Private Bag 93503, Takapuna, Auckland 0740, New Zealand

6 Department of Cardiology, Middlemore Hospital, Counties Manukau District Health Board, Private Bag 93311, Otahuhu, Auckland 1640, New Zealand

7 Department of Renal Medicine, Auckland City Hospital, Auckland District Health Board, Private Bag 92024, Auckland 0740, New Zealand

8 Department of Nephrology, Christchurch Hospital, Canterbury District Health Board, Private Bag 4710 Christchurch, New Zealand

9 Department of Nephrology, Wellington Hospital, Wellington, New Zealand

10 Department of Renal Medicine, Waikato Hospital, Waikato District Health Board, Private Bag 3200, Hamilton 3240, New Zealand

11 Nephrology Service, Dunedin Hospital, Southern District Health Board, 201 Great King St, Dunedin, New Zealand

12 Medical Affairs - Renal Asia Pacific, Baxter Healthcare Pty Ltd, P.O. Box 14062, Panmure, Auckland 1741, New Zealand

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BMC Nephrology 2014, 15:120  doi:10.1186/1471-2369-15-120

Published: 21 July 2014



The Sodium Lowering in Dialysate (SoLID) trial is an ongoing a multi-center, prospective, randomised, single-blind (assessor), controlled, parallel assignment clinical trial, enrolling 96 home and self-care hemodialysis (HD) patients from 7 centers in New Zealand. The trial will evaluate the hypothesis that lower dialysate [Na+] during HD results in lower left ventricular (LV) mass. Since it’s inception, observational evidence has suggested increased mortality risk with lower dialysate [Na+], possibly due to exacerbation of intra-dialytic hypotension and subsequent myocardial micro-injury. The Myocardial Micro-injury and Cardiac Remodeling Extension Study in the Sodium Lowering In Dialysate Trial (Mac-SoLID study) aims to determine whether lower dialysate [Na+] results in (i) increased levels of high-sensitivity Troponin T (hsTnT), a well-established marker of intra-dialytic myocardial micro-injury in HD populations, and (ii) increased fixed LV segmental wall motion abnormalities, a marker of recurrent myocardial stunning and micro-injury, and (iii) detrimental changes in LV geometry due to maladaptive homeostatic mechanisms.


The SoLID trial and the Mac-SoLID study are funded by the Health Research Council of New Zealand. Key exclusion criteria: patients who dialyse > 3.5 times per week, pre-dialysis serum sodium <135 mM, and maintenance haemodiafiltration. In addition, some medical conditions, treatments or participation in other dialysis trials that contraindicate the study intervention or confound its effects, will be exclusion criteria. The intervention and control groups will receive dialysate sodium 135 mM and 140 mM respectively, for 12 months. The primary outcome measure for the Mac-SOLID study is repeated measures of [hsTnT] at 0, 3, 6, 9, and 12 months. The secondary outcomes will be assessed using cardiac magnetic resonance imaging (MRI), and comprise LV segmental wall motion abnormality scores, LV mass to volume ratio and patterns of LV remodeling at 0 and 12 months.


The Mac-SoLID study enhances and complements the SoLID trial. It tests whether potential gains in cardiovascular health (reduced LV mass) which low dialysate [Na+] is expected to deliver, are counteracted by deterioration in cardiovascular health through alternative mechanisms, namely repeated LV stunning and micro-injury.

Trial registration

Australian and New Zealand Clinical Trials Registry number: ACTRN12611000975998.

Home hemodialysis; Self-care hemodialysis; Dialysis; Left ventricular mass; Left ventricular remodelling; Myocardial stunning; Sodium; Blood pressure; Intra-dialytic hypotension; Dialysate