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Background Several mapping systems are being introduced to guide atrial fibrillation (AF) ablation to patient-specific regions of interest. However, results have been extremely heterogeneous between studies, ranging from very poor to very promising. It is unknown if this reflects specific patient characteristics or procedural factors because most prior series were middle sized (N∼30–100 patients). Purpose To study 1 year and 3 year very long-term outcomes from map guided AF-driver ablation in a large patient registry with multiple operators, to identify clinical and procedural features influencing outcomes. In real-world AF patients with diverse comorbidities, we applied a consistent patient-tailored AF mapping and ablation strategy, monitored outcomes carefully and applied statistical and unsupervised machine learning approaches to identify features of success and failure. Method We studied 632 consecutive patients (65±10 y, 178 F) undergoing ablation for drug-refractory AF. 59.7% had persistent AF, and 29.9% had prior unsuccessful ablation (median 1 procedure). All patients underwent pulmonary vein isolation (PVI), followed by ablation of AF regions of interest mapped from 64 pole baskets (RhythmView, Abbott, IL), by 11 operators. Patients were followed using ambulatory ECG monitors quarterly for one year, and at the time of symptoms for 3 years. Results Fig. 1A shows overall freedom from AF at 1-year of 77.5% (95% CI: 74.2%, 80.9%) and at 3 years of 55.5% (95% CI: 51.2%, 60.1%). Freedom from AF/AT at 1-year was 70.1% (95% CI: 66.5%, 73.8%), and at 3 years was 48.6% (95% CI: 44.3%, 53.3%). Success was higher in patients with procedural termination, first ablation versus prior unsuccessful procedures, for paroxysmal AF than non-paroxysmal AF (1 year: AT/AF freedom 74.9% versus 66.7%, p=0.006), and smaller left atrium. Three clusters (Fig 1B) were identified comprising CHA2DS2VASc score, enlarged LA, prior failed case, presenting rhythm and termination during the procedure (Table 2). At 1 year, freedom from AT/AF was 77.8% (95% CI: 72.2%, 82.1%) for cluster 3 and 56.2% (95% CI: 48.3%, 65.4%) for cluster 1 (Fig. 1B). Conclusion In our large registry of N=632 patients undergoing AF-map guided ablations, machine learned clusters identified cohorts with success of 56.2 to 77.8% at 1 year. Future studies should identify if lower success represents technical challenges, such as difficulties in mapping very large atria, or more difficult to treat mechanisms. These results may inform patient inclusion and ablation strategy in upcoming AF treatment trials. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National budget only - NIH, R01 HL149134, R01HL83359

Brackish groundwater is one of the major natural water resources presently available in Kuwait. In spite of its poor quality, with total dissolved solids (TDS) of about 3000 ppm, it is increasingly used for landscaping, gardening and agriculture. Extensive use of poor quality groundwater has resulted in several problems. These are: (1) declining groundwater levels by as much as 50 m; (2) deterioration of groundwater quality in agriculture areas due to the return of irrigated water- the TDS of groundwater increased to about 8000 ppm at selected sites; and (3) excessive use of groundwater for landscaping and gardening in urban areas has resulted in the rise of groundwater levels by about 3 m, threatening the integrity of several buildings and roads. The most feasible solutions to these problems are (1) replacing the use of groundwater with artificially recharged and stored treated wastewater in aquifers; (2) reverse osmosis treated groundwaterfor urban and irrigation use at an appropriateprice; and...

The Gulf War resulted in the contamination of large areas of ground surface in Kuwait. In northern Kuwait, ground water of potable quality exists as lenses and the integrity of these lenses is threatened by the pollution over the ground surface. In 1991, the total area covered by oil lakes, oil sludge, and soot in northern Kuwait was about 32 km2, 5 km2, and 150 km2, respectively. Several natural and man‐made measures significantly affected the distribution of contaminants. In 1995, the area covered by oil lakes, oil sludge, and soot changed to 2 km2, 35 km2, and 25 km2, respectively. Soil samples were collected to depths of 10 m. The analysis of soil samples showed maximum contaminant levels of about 20 ppm, 10 ppm, and 1 ppm at ground surface, 4 m and 10 m depths, respectively. Rainfall played a significant role in the downward movement of contaminants to depths in excess of 10 m in 1995.

Massive oil fires in Kuwait were the aftermath of the Gulf War. This resulted in the pollution of air, water, and soil, the magnitude of which is unparalleled in the history of mankind. Oil fires damaged several oil well heads, resulting in the flow of oil, forming large oil lakes. Products of combustion from oil well fires deposited over large areas. Infiltrating rainwater, leaching out contaminants from oil lakes and products of combustion at ground surface, can reach the water table and contaminate the groundwater. Field investigations, supported by laboratory studies and mathematical models, show that infiltration of oil from oil lakes will be limited to a depth of about 2 m from ground surface. Preliminary mathematical models showed that contaminated rainwater can infiltrate and reach the water table within a period of three to four days, particularly at the Raudhatain and Umm Al-Aish regions. These are the only regions in Kuwait where fresh groundwater exists. After reaching the water table, the lateral movement of contaminants is expected to be very slow under prevailing hydraulic gradients. Groundwater monitoring at the above regions during 1992 showed minor levels of vanadium, nickel, and total hydrocarbons at certain wells. Since average annual rainfall in the region is only 120 mm/yr, groundwater contamination due to the infiltration of contaminated rainwater is expected to be a long-term one.

Host of the soluble iron in groundwater exists in complexes with organic matter. Removal of iron, complexed with organic matter, is difficult and requires the use of a strong oxidant such as ozone, chlorine, etc. This increases capital and operating costs of water treatment plants. Iron oxidizing bacteria like Gallionellaferruginea are known to oxidize iron and derive the energy for the reduction of CO2. A biological reactor was developed, based on these principles, to remove iron from groundwater. The reactor was successful in reducing iron levels in groundwater from 2.5-3.0 mg/l to about 0.1 mg/l. It was observed that, apart from Gallionellaferruginea, Sphaerotilus spp. were also present in the reactor column. No major problems with respect to clogging of filters or the reactor column were experienced.

Tomago sandbeds (New South Wales, Australia) is a coastal unconfined aquifer, where mining of mineral sands, like Rutile, Zircon, Ilmenite etc., was in progress since 1972. Groundwater is also extracted from Tomago aquifer for urban water use. Groundwater iron levels vary from 0.1 mg/litre to about 10 mg/litre. Iron in excess of 0.3 mg/litre is removed by chemical treatment. Mining of mineral sands resulted in the substantial increase of iron levels. The level of increase itself being very site specific. Several processes were identified as being responsible for such increases. If water were to be extracted from the mined area, additional treatment would be required to remove excess iron.

Treatment of wastewater by the high rate land infiltration system is known as soil aquifer treatment (SAT). SAT is a proven technique for the improvement of wastewater quality. The quality of wastewater produced after SAT is suitable for unrestricted irrigation. The experimental study undertaken at Sulaibiyah proved that the method could be successfully used in Kuwait. The gatch layers within the subsurface region posed no major problems for the infiltration of the wastewater. The groundwater conditions at Sulaibiyah are suitable for the storage of large volumes of wastewater. The cost of treatment by SAT is considerably less than that of conventional methods.

The soil parameters that determine the infiltration rates of a shallow unconfined coastal aquifer due to rainfall were obtained using the recursive least squares method. The parameters were predicted by minimizing the mean square error between the estimated and measured water-table levels in a bore hole. The parameters λt , a drainage factor, βt , a parameter which accounts for external disturbances, and αt , a set of parameters which determine the infiltration rates due to rainfall, were all treated as time-dependent variables. Their variation is traced by introducing a "forgetting factor" in the algorithm used to determine the parameters. The parameters were determined using rainfall and water-table levels for the year 1979 at a bore hole. The parameters βt and αt varied considerably over the period of time and λt remained constant. From the parameters obtained, it appears that most of the recharge due to rainfall takes place within the first two days of the event. After two days there is very little variation in the water-table level due to rainfall although there is a slight drop on the third, fourth and fifth day, presumably due to the escape of entrapped air beneath the water-table level.